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Al-Dirini, Rami M.A., Reed, Matthew, Paul, Gunther, & Thewlis, Dominic(2012)A subject-specific model of human buttocks and thighs in a seated posture.InKotousov, Andrei (Ed.)Book of Abstracts: 7th Australasian Congress on Applied Mechanics(ACAM7), The University of Adelaide, University of Adelaide, Adelaide,SA.
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http://www.engineersaustralia.org.au/events/7th-australasian-congress-applied-mechanics
Book of Abstracts
7th Australasian Congress on Applied Mechanics (ACAM 7)
9th – 12th December 2012
The University of Adelaide
Editor A/Prof Andrei Kotousov
Compiled by Engineers Australia, 2012
Table of Contents
Welcome Letter by the ACAM 7 Chair ................................................................................................ 10
The Origin of ACAM by Bob Randall and Raphael Grzebieta .......................................................... 11
The Legacy of ACAM by Francis Rose ............................................................................................... 14
Organising Committee ......................................................................................................................... 15
Technical Committee ........................................................................................................................... 17
Keynote Speakers ................................................................................................................................ 20
Keynote Abstracts ................................................................................................................................ 27
Can we really predict accurately the strength of adhesively bonded joints? ...................................... 28 Robert D. Adams
The mechanics and mechanisms of fracture of nano-modified polymers ........................................... 29 Anthony J. Kinloch
Passive and active hydraulically interconnected suspensions and their applications ........................ 30 Nong Zhang
Stress-Intensity factors and fatigue growth for surface cracks ........................................................... 31 Andrea Carpinteri
Design, nanomanufacturing, and mechanics of novel superstrong / tough continuous nanofibers and next generation supernanocomposites ............................................................................................... 32
Yuris Dzenis
Presented Abstracts
Session 1: Fracture Mechanics I ......................................................................................................... 34
Evolution of compliance in round bars subjected to tensile and bending fatigue cracking ................. 34 Jesús Toribio
The short crack anomaly in aerospace structural materials ............................................................... 35 Rhys Jones
Coupled fracture modes in three-dimensional fracture mechanics ..................................................... 36 Andrei Kotousov
Modelling the complex manufacturing history of a pipework joint, assessment of its through life creep-fatigue and calculation of the J-Integral using finite element based methods .......................... 37
Mark J. Stevens
An Investigation on rail squat prediction due to rolling contact fatigue ............................................... 38 Mohammadali Farjoo
Session 2: Dynamics I ......................................................................................................................... 39
Bearing fault simulation using finite element model updating and reduction techniques .................... 39 Lav G. Deshpande
Identification of foundations in rotating machinery using modal parameters ...................................... 40 Minli Yu
A bearing fault classifier using Artificial Neuro-Fuzzy Inference System (ANFIS) based on statistical parameters and Daubechies wavelet transform features ................................................................... 41
Jonny Latuny
Correlation of vibration and cutting forces in thin-walled machining ................................................... 42 Majed Masmali
Cepstrum-based operational modal analysis: regeneration of frequency response functions ........... 43 Robert B. Randall
Session 3: Bio-Mechanics I ................................................................................................................. 44
A subject-specific model of human buttocks and thighs in a seated posture ..................................... 44 Rami M.A Al-Dirini
Finite element analysis of an implant-assisted removable partial denture with different positions of the rest arm......................................................................................................................................... 45
Reza Shamiri
On the influence of acetabular cup wear and orientation on contact mechanics of dual mobility hip implants .............................................................................................................................................. 46
Mohammad S. Uddin
Develop and validate a biomechanical surrogate of the human thorax using corrugated sheets: A feasibility study ................................................................................................................................... 47
Narasimha MurthyThota
Use of a damped Hertz contact model to represent head impact safety tests ................................... 48 Daniel J. Searson
Session 4: Composites I ...................................................................................................................... 49
Effects of adherend thickness on the bond strength measurement of adhesive bonded repairs ....... 49 Mildred Lee
Flexure analysis of composite pipes during reeling process .............................................................. 50 Muhammad A. Ashraf
Investigation on the wrinkling limit diagram of self-reinforced polypropylene woven composite at room temperature ........................................................................................................................................ 51
Nima A. Zanjani
Numerical investigation of the effect of temperature on the formability of a thermoplastic fibre metal laminate .............................................................................................................................................. 52
Sivakumar DharMalingam
Session 5: Dynamics II ........................................................................................................................ 53
Modification of the ISO-10816 centrifugal pump vibration severity charts for use with Octave band spectral measurements ...................................................................................................................... 53
Kristoffer K. McKee
Investigation of influence of technological imperfections on the dynamic behavior of the packages of the steam turbine blades .................................................................................................................... 54
Iuliia Karachevtseva
Stationary points created by resonances in a chain of bilinear oscillators .......................................... 55 Igor Shufrin
Comparison of interval method and Polynomial Chaos method for solving dynamics problem with uncertainties ....................................................................................................................................... 56
Jinglai Wu
Session 6: Bio-Mechanics II ................................................................................................................ 57
Investigation of nano-mechanical properties of cartilages of sheep knee joints ................................. 57 Zhongxiao Peng
Effects of irradiation and non-enzymatic glycation on the fracture resistance of bovine cortical bone ............................................................................................................................................................ 58
Lloyd Fletcher
Determination of stress field caused by microprojection arrays contacting and impacting hyperelastic layered skin......................................................................................................................................... 59
Stefano C. Meliga
Parametric studies of optic chiasmal compression biomechanics using finite element modelling ..... 60 Xiaofei Wang
Session 7: SHM & NDT I ...................................................................................................................... 61
Investigating mode coupling effects in composites beams with delamination damage ...................... 61 Jiawen Su
Model updating based structural damage detection of transmission tower: experimental verification by a scaled-model ............................................................................................................................... 62
Jiahua Yang
The low-frequency scattering of the A0 Lamb wave from delaminations in quasi-isotropic composite laminates: Theoretical and finite element studies ............................................................................... 63
Ching-Tai Ng
Numerical investigation of the scattering of ultrasonic guided wave in hard-to-inspect regions ......... 64 Cain Doherty
Session 8: Manufacturing .................................................................................................................... 65
Effect of aspect ratio variations on forming limit diagram of glass-fibre reinforced polypropylene composite at room temperature .......................................................................................................... 65
Nima A. Zanjani
Parametric influence and optimization of wire-EDM on hot die steel .................................................. 66 Nixon Kuruvila
Forming of housing by impact extrusion press using ultrafine-grained semi-solid light metal ............ 67 Keiko Natori
Development of a trajectory-based 3D surface roughness model for the micro end-milling process . 68 Shah M. M. Rahman
Session 9: Life Assessment ................................................................................................................ 69
Non-linear peculiarities of creep in irradiated materials ...................................................................... 69 Pavlo Selyshchev
Life assessment of welded joints operating within creep range .......................................................... 70 Mridul A. Pramanik
Improving structural integrity assessment of nonlinear packaging materials ...................................... 71 Matthew J. Lamb
A simple tool for simulating the growth of rail squats .......................................................................... 72 Daren Peng
Session 10: Nano & Micro Mechanics ................................................................................................ 73
Gradient model of adhesion: mechanical properties and fracture of micro/nano-structured materials ............................................................................................................................................................ 73
Sergey Lurie
Origin of the implantation and annealing effects on the residual stress release in a silicon-on-sapphire system .................................................................................................................................. 74
Mei Liu
A note on the reliability of nanoindentation: effect of sample standing ............................................... 75 Fengzai Tang
The mechanism of nano-scale shear banding in metallic glass ......................................................... 76 Weidong Liu
Strength anisotropy and mixed mode fracture in cold drawn prestressing steel wires ....................... 77 Jesús Toribio
Session 11: SHM & NDT II ................................................................................................................... 78
Model updating of the rail-sleeper-ballast system and its application in ballast damage detection .... 78 Qin Hu
Location and depth of delamination damage determined by an inverse method ............................... 79 Shuai He
Integrating structural health monitoring into structural design ............................................................ 80 Wern H. Ong
An experimental investigation of damaged plain-weave reinforced laminates using modal analysis . 81 Mehmet Yetmez
Model updating and the detection of joint defects utilizing measured vibration data .......................... 82 Heung F. Lam
Session 12: Solid Mechanics I ............................................................................................................ 83
Super-harmonic resonance response of a quadratically nonlinear oscillator involving time delay ..... 83 Jinchen Ji
The analytical solution of contact problem about torsion of transversely isotropic elastic half-space with an inhomogeneous coating ......................................................................................................... 84
Andrey Vasilyev
Homogenisation methods in mechanics of fragmented solids and hybrid materials .......................... 85 Elena Pasternak
On the non singular higher order terms in bi-dimensional and three-dimensional engineering applications ......................................................................................................................................... 86
Filippo Berto
An assessment of two statistical models for elastic contact analysis between rough surfaces .......... 87 Xiaoling Jin
Poster Sessions ................................................................................................................................... 88
Mini- trampoline as a human structural vibration exciter .................................................................... 88 Leonard L. Koss
Probabilistic approach in fatigue of crankshaft by using Markov Chain Model ................................... 89 Nik Abdullah Nik Mohamed
An analytical – FEA approach to lifetime estimation of mining equipments ....................................... 90 Cătălin Iancu
Prediction of welding residual stresses in flat plate(X80) ................................................................... 91 Houman Alipooramirabad
Extraction and application of cellulose nanofiber from waste materials ............................................. 92 Hitoshi Takagi
Minimising solid particle erosion in an annular cavity ......................................................................... 93 Chong Y. Wong
Experimental study for electrochemical discharge machining (ECDM) cutting using a stratified disk transfer ............................................................................................................................................... 94
Alin Nioaţă
Transient response for different support of pipes with flowing medium subjected to impulse loading 95 Roslina Mohammad
Finite element modelling of heat exchange in the stroke-affected brain during therapeutic hypothermia ........................................................................................................................................ 96
Thomas Lillicrap
Using 3D Scanning laser vibrometre for imaging delimitation defects in composites ......................... 97 Pouria Aryan
Research on the influence of rubber waste and devulcanization technology on the characteristics of reclaimed rubber ................................................................................................................................. 98
Dan Dobrotă
Tailored microstructure creation of TiAl-based refractory alloys within VGF solidification ................. 99 Andrey V. Kartavykh
Numerical simulation of multicomponent alloy solidification ............................................................. 100 Vladimir P. Ginkin
Session 14: Automotive Research I ................................................................................................. 101
Dynamics and control of gear shifts in a two speed electric vehicle ................................................. 101 Paul D. Walker
Empirical analysis of a roll-plane hydraulically interconnected suspension system under vehicle articulation mode .............................................................................................................................. 102
Holger M. Roser
Using canonical variate analysis to detect engine misfires ............................................................... 103
Modelling and parameter estimation of an active hydraulic suspension using experimental method .......................................................................................................................................................... 104
Lifu Wang
Session 15: Composites II ................................................................................................................. 105
On the forming behaviour of woven thermoplastic composite materials .......................................... 105 Sudharshan Venkatesan
Detecting delamination in a composite structure using an embedded FBG – AE hybrid system ..... 106 Gayan C. Kahandawa
Influence of microwave energy on mechanical strength in sugarcane ............................................. 107 Ling Yin
Finite element analysis of the formability of carbon fibre/PEEK composite sheets .......................... 108 Sebastian Davey
Session 16: Automotive Research/ Sustainability .......................................................................... 109
Experimental study of anew solar-assisted air-conditioner for performance prediction and energy saving ............................................................................................................................................... 109
Vahid Vakiloroaya
Research on determining the coefficient of environmental pollution produced by automatic submerged arc welding ..................................................................................................................... 110
Gheorghe Amza
Evaluation of experimental techniques for establishing vehicle suspension characteristics ............ 111 Daniel T. Ainalis
Literature review of pedestrian injury severity with vehicle impact speeds and the development of curves to predict pedestrian injury likelihood (AIS 1 to AIS 6) versus vehicle impact speeds .......... 112
Tandy W. P. Pok
Session 17: Fluid-Structure ............................................................................................................... 113
Single-image attenuation corrections to facilitate instantaneous planar imaging of densely seeded particle-laden flows ........................................................................................................................... 113
Mei C. Cheong
A review of skin friction drag reduction within the turbulent boundary layer ..................................... 114 Farzin Ghanadi
Performance analysis and optimisation of bend-twist coupled composite hydrofoils using fluid-structure interaction .......................................................................................................................... 115
Manudha T. Herath
Turbulent wake study of NREL phase VI wind turbine in a virtual wind tunnel using Large Eddy Simulation ......................................................................................................................................... 116
Amanullah Choudhry
Experimental study of the flow structure in a vortex tube ................................................................. 117 Yunpeng Xue
Session 18: Rock Mechanics ............................................................................................................ 118
Steady flow towards a row of collinear hydraulic fractures ............................................................... 118 Aditya Khanna
On the residual opening of cracks with rough faces stimulated by shear slip .................................. 119 Luiz Bortolan Neto
Development of a standard method for determining the plane strain fracture toughness of rock .... 120 Mahinda D. Kuruppu
Effect of grain bonding on the stability of a borehole drilled through low cemented formations ....... 121 S.Saeid Hashemi
A method for estimating the fracture toughness of rocks ................................................................. 122 Qingyu Yao
Session 19: Solid Mechanics II ......................................................................................................... 123
Development of a rapid drop test for surface quality inspection ....................................................... 123 Christopher Y. Thang
A numerical study of the impact properties of sandwich panels with different cores ........................ 124 Karthik Ram Ramakrishnan
Testing in order to measure the protection against impact of people, manufactured items, and agricultural produce: How to consider all severities of shock ........................................................... 125
Timothy P. Hutchinson
Experimental characterisation of the formability of a thermoplastic fibre metal laminate ................. 126 Anthony Sexton
Strip buckling from side-guard contact during strip rolling ................................................................ 127 Andrew Dixon
Session 20: Composites III ................................................................................................................ 128
Effect of preheat temperature on the formability of carbon fibre/PEEK composites ......................... 128 Sebastian Davey
Exploring the potential for Vacuum Assisted Oven Consolidation (VAOC) of Natural Fibre Reinforced Thermoplastic Sheets (NFRTS) ........................................................................................................ 129
Syed Monis R. Kazmi
Development and performance of all bamboo-based green composites ......................................... 130 Hitoshi Takagi
Structural composites embedded with lithium polymer batteries ...................................................... 131 Salah M. Shalouf
Session 21: Computational Mechanics ............................................................................................ 132
Finite element simulation of the stretch forming of annealed aluminium sheets .............................. 132 Anthony Sexton
Methods for determining rubber and composite materials with rubber matrix breaking resistance .. 133 Dan Dobrotă
The modification of finite element model of a coupled slab system utilizing measured modal parameters........................................................................................................................................ 134
Hua Y. Peng
A new approach to the investigation of mixed lubrication in metal strip rolling ................................. 135 Mohammad N. Khan
Session 22: Optimization / System Identification ........................................................................... 136
Topology optimization of lightweight structures using a meshless Shepard function approximant .. 136 Zhen Luo
A new multi-objective robust optimisation methodology ................................................................... 137 Jendi I. Kepple
Application of extended, unscented, iterated extended and iterated unscented Kalman Filter for real-time structural identification .............................................................................................................. 138
Mohsen Askari
Adaptive multiple forgetting factor recursive least square (AMFF-RLS) for real-time structural identification with unknown input ...................................................................................................... 139
Mohsen Askari
Session 23: Dynamics III ................................................................................................................... 140
Characterisation of trampoline bounce using acceleration ............................................................... 140 David Eager
On chaotic interaction between product and cushioning during random vibration testing of protective packaging for transportation ............................................................................................................. 141
Michael A. Sek
Vertical vibrations and detachments of drill bits in rotary drilling ...................................................... 142 Arcady V. Dyskin
Dynamic analysis of beam with multiple cracks using Transfer Matrix Method ................................ 143 Nik Abdullah Nik Mohamed
Session 24: Engineering Education/Composites ............................................................................ 144
“If I record my lectures, no one will attend my class”: The transition to multi-modal delivery in Applied Mechanics Education ........................................................................................................................ 144
Colin Kestell
Teaching first year engineering dynamics at a small and large Australian University ...................... 145 Zhongxiao Peng
Improved student engagement in civil and mechanical engineering using a professional peer feedback process.............................................................................................................................. 146
Craig R. Willis
Finite element modelling and analysis of a filament wound spinning composite disk ...................... 147 Md Sayem Uddin
Session 25: Fracture and Solid Mechanics ..................................................................................... 148
Plasticity-induced crack closure model for two collinear cracks in plates of arbitrary thickness ....... 148 Donghoon Chang
Bending strain measurements utilising a scanning laser Doppler vibrometer .................................. 149 Stuart J. Wildy
Application of Bayesian updating to the risk analysis of aircraft structures ...................................... 150 Ribelito F. Torregosa
Additional Papers ............................................................................................................................... 151
Modelling shear behaviour of EPS-sand based on elliptic-parabolic yield surfaces model .............. 152 An Deng
Evaluation of existing models of FRP-to-concrete debonding failure ............................................... 153 Ardalan Hosseini
Effects of suction on flow characteristics around circular cylinders based on numerical modelling . 154 Abdol R. Kabiri- Samani
Crack monitoring of RC beams using digital image analysis technique ........................................... 155 Ardalan Hosseini
Application of image processing method in experimental modeling of one dimensional dam break wave ................................................................................................................................................. 156
Anahita Jouzdani
Authors and Papers Index ................................................................................................................. 157
Authors and Pages Index .................................................................................................................. 159
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Welcome Letter by the ACAM 7 Chair May I extend a warm welcome to all the participants of the 7th Australasian Congress on Applied Mechanics (ACAM7) held at the University of Adelaide in South Australia. Applied Mechanics is one of the oldest fields of science. Moreover, it is one that continues to evolve and advance, driven by a multitude of needs arising in practically all areas of technology as well as other human activities. For example, sustainability was one of the major considerations and driving forces over the past decade. Recent fundamental developments are made possible by new, advanced instrumentation making way for new, decisive experiments and the adoption of powerful computational approaches. Our discipline uses these tools in its ambition to gain a deep understanding of material behaviour at various scales; to achieve superior mechanical characteristics of machines and structures and to attain predictability and the prevention of damage and catastrophic failures. We are delighted in bringing researchers from all parts of Australia to Adelaide and extend a special welcome to first time attendees and visitors from further afield; 25 countries will be represented at our conference. This conference is the seventh congress organised under the leadership of the National Committee on Applied Mechanics (NCAM) of Engineers Australia. Normally held every two or three years, the previous ACAM was held in Perth in 2010. This conference promises to be a lively high-quality event covering a wide range of topics in Applied Mechanics including fracture mechanics, nanotechnology, composite materials, multiscale modelling, non-destructive evaluation and biomechanics. We are privileged to have six internationally renowned keynote speakers and 130 contributed papers that will be presented and will appear in the published conference proceedings. All accepted papers have been peer reviewed by experts in the relevant field in order to ensure the high technical standards of the conference. This conference is hosted by a Local Organising Committee. I am grateful to them, as well as the Technical Committee for their work and guidance in bringing the conference to its realisation. I also thank the many people who contributed through the reviewing process. The support of the University of Adelaide, The Institute for Mineral and Energy Resources (IMER), Engineers Australia and the Applied Mechanics National Committee has been very much appreciated. Finally, we must not forget that any Congress is importantly a meeting place for colleagues and friends who have a common interest, in this case, Applied Mechanics. Adelaide is the perfect place for this purpose. The city has both quiet and exciting places to visit and walk around; in short, it is an ideal site for a great scientific and social program. I wish you a fruitful conference and hope that while you absorb all of the technical and networking opportunities you also find the time to enjoy the beautiful and friendly city of Adelaide.
Associate Professor Andrei Kotousov Chair, ACAM 7
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The Origin of ACAM by Bob Randall and Raphael Grzebieta The idea to institute a regular series of conferences on Applied Mechanics grew out of a successful conference on “Dynamic Loading in Manufacturing and Service” held in Melbourne in February 1993, which in itself was the first of its kind in Australia. A total of 35 papers were presented, of which four were Keynote presentations on Strain Rate Dependent Deformation, Explosive Metal Forming, Crash Dynamics, and Impact, Penetration and Erosion, the latter by Dr William Gooch of the US Army Research Laboratory, Aberdeen Proving Ground, Maryland. Dr Gooch and a group of colleagues from the USARL also attended at least the first two ACAM conferences three and six years later. The Chair of the conference was Neil Page, at the time an Associate Professor at the University of Queensland, and Chair of the National Committee on Applied Mechanics (NCAM) of the Institution of Engineers, Australia. Neil notes in the foreword of that conference that:
“There is no specific goal of generating an on-going regular conference, but rather the hope is that people, having been made aware of the parallel activities, will increase communications among themselves as appropriate. This may take the form of workshops, seminars, short courses, discussion groups or even a regular conference”.
Even so, the NCAM quickly formed the opinion that a regular conference would be of value, but that its scope should be widened to cover the whole field of Applied Mechanics (as defined within the remit of the NCAM – more about this later). It was also decided that it should be an international conference, so as to expose Australian engineers to what was going on in the rest of the world, as well as promoting the work being done in Australia to a wider audience. It was decided to make it an “Australasian” conference, mainly on the assumption that it would be of interest to our colleagues in New Zealand, without specifically making contact with them. The question of what constituted “applied mechanics” was effectively decided by the area covered by the NCAM of the Mechanical College of Engineers Australia, formerly the Institution of Engineers Australia (IEAust). In particular, this does not include fluid mechanics, even though this for example lies within the scope of the International Union of Theoretical and Applied Mechanics (IUTAM). This was because this area was already well served within Engineers Australia by the Australasian Fluids and Thermal Engineering Society (AFTES), which held international conferences every three or four years on Heat and Mass Transfer. The comment was made that just as politicians (at the time) were grouped into “wets” and “dries”, so were proponents of applied mechanics, and ACAM catered only for the “dries”. The first ACAM conference (ACAM 1) was held at the Carlton Radisson Hotel in Melbourne from 21-23 February 1996. In fact it was titled ‘The First Australasian Congress On Applied Mechanics’. The organizing committee was headed by Dr. Raphael Grzebieta of Monash University as Chair, with the other officers of the committee, Dr. Ray Woodward, John Marco and Dr Albert Wong all from DSTO Fishermans Bend. Raphael took over from Ray who was the Founding Chair but had
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subsequently passed the baton on because of other commitments. The conference was very successful, with over 200 papers submitted from more than 20 countries. The Minister for Industry and Employment as well as for Regional Development, the Hon Phillip Gude, MP, provided the Foreword in the program welcoming all delegates and supporting the conference. The conference was opened by the Chair of NCAM, A/Prof. Bob Randall. Proceedings were published in a two volume set with all papers peer-reviewed by at least two reviewers. The conference was acknowledged by Dr. Clive Chirwa, Editor in Chief of the International Journal of Crashworthiness where selected papers were published in the 1996 Vol 1 No 3 edition (see: DOI:10.1533/cras.1996.0031), further elevating the conference’s outcomes internationally. Dr. Chirwa commented in the journal: “The Congress broke new ground in that for the first time in Australia, it provided a forum in which international researchers, engineers and designers from diverse areas of applied mechanics could meet to share expertise, experience and innovative ideas with special emphasis on the behaviour of solids under instantaneous loading and biomechanics.” The range of topics covered was grouped under the following headings:
Dynamic Loading and Crash Dynamics Fracture Mechanics, Fatigue and Failure Analysis CAE/CAD Composite Materials and Structures Particle Mechanics/Systems Bio-Engineering/Biomechanics Stress Analysis and Material Testing Geomechanics Dynamics, Vibration and Condition Monitoring, and Mechanics of Shaping Processes
There were three Keynote Speakers:
Professor Don Stauffer, Department of Aerospace Engineering, Cincinnati on “Inelastic Constitutive Modeling of metals”
Dr John Hallquist, the originator of Dyna 3D (now LS DYNA) on “Explicit Finite Element Methods for Impact Engineering”
Professor Alexander Linkov, Institute for Problems of Mechanical Engineering, Russian Academy of Sciences on “Computational Mechanics in Russia: Subject and Problems”
Another feature of ACAM 1 was the 23rd L.P. Coombes Memorial Lecture celebrating the origins of Aeronautical Science in Australia, presented by Dr. Gordon Long entitled ‘Research and Development Needs of the Australian Aeronautical Industry”. Also one of the plenary sessions on the last day was set aside as a panel workshop, where the state of Applied Mechanics in Australia was discussed and future directions were proposed.
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Because of the success of ACAM 1, it was decided by the NCAM to repeat the exercise roughly every three years, and so ACAM 2 was held at the Australian Defence Force Academy (ADFA) in Canberra from 10-12 February, 1999, under the chairmanship of Professor John Baird. It was attended by 94 delegates from 16 countries, who presented 85 papers. ACAM continued to be held every three years from then on (interval now shortened to two years) and has lived up to the original hopes of the NCAM to provide a forum for practitioners of the various fields of Applied Mechanics to meet regularly to present developments in their own field and learn of the latest developments in other fields, not least from overseas attendees. Bob Randall Chair NCAM, 1996 Raphael Grzebieta Chair ACAM 1, 1996
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The Legacy of ACAM by Francis Rose
It has been my privilege to be closely associated with the ACAM conferences since their inception. In this introduction, it is appropriate to pay tribute to Neil Page (University of Newcastle) and the late Ray Woodward (Defence Science and Technology Organisation), who were pivotal in proposing and promoting the concept of a local series of conferences on Applied Mechanics, under the auspices of the National Committee for Applied Mechanics (NCAM) of the Mechanical College Board of Engineers Australia.
Starting with the inaugural ACAM, which was held in Melbourne in 1996, successive organizing committees have provided distinctive features to their individual conferences, while remaining consistent with the overall objective of providing a high-quality forum for researchers and practitioners to present their work and exchange ideas and insights.
As a former chairman of NCAM, I was instrumental in fostering the view of ACAM as the flagship activity for that committee, and in promoting the role of ACAM in attracting and retaining graduate students who would constitute a pool of potential future researchers and practitioners. Thus, the presentation of awards for the best student paper presented at the conference, and for the best teaching innovation or practice in Applied Mechanics, has become an integral and valued part of ACAM.
In addition, the choice of themes for each conference, and of distinguished national and international researchers and practitioners as the keynote speakers for those themes, has helped to ensure the high quality of ACAM conferences to date.
I am confident that ACAM7 will live up to that enviable track record and I look forward to attending another stimulating and invigorating ACAM in Adelaide this December 2012.
Francis Rose Emeritus Research Leader Air Vehicles Division, DSTO
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Organising Committee
Conference Chairman: A/Prof Andrei Kotousov The University of Adelaide BE (Hons), PhD (Russian Academy of Sciences), MIEA
A/Prof Andrei Kotousov joined The University of Adelaide in 2002 as a lecturer in the School of Mechanical Engineering. Prior to this appointmenthe was a Research Scientist with Russian Academy of Sciences from 1993to 1997, Research Associate at Victoria University of Technology and Senior Research Fellow with Monash University. His academic andresearch career has largely focused on Fracture and Solid Mechanics,Composites and Bio-mechanics. Conference Deputy Chair: A/Prof Colin Kestell The University of Adelaide BSc Hons (Coventry), PhD (The University of Adelaide) Colin left school at sixteen to commence his apprenticeship and spent seventeen years working in the aerospace and defence sectors of engineering. The last six of these was as a laboratory manager, responsible for the testing of Australian defence products in NSW. A sea change resulted in a move to Adelaide, a PhD and a new found passion: teaching. Since he began his academic career he has always been extremely interested in the quality of education and the students’ learning experiences. Colin is the Associate Dean for Learning and Teaching in the Faculty of Engineering, Computer and Mathematical Sciences at the University of Adelaide
Member: Dr Stuart Wildy Flinders University BE (Hons), PhD (University of Adelaide), GradIEAust
Dr Stuart Wildy is a lecturer in the School of Computer Science,Engineering and Mathematics at Flinders University of South Australia. Hegraduated with honours from the University of Adelaide with a Bachelor of Engineering (Mechatronics) in 2006 and completed his PhD at the sameinstitution in 2012. His academic and research interests include structural health monitoring, experimental stress analysis, non-destructive testing, fracture mechanics, and composite materials.
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Member: A/Prof Ben Cazzolato The University of Adelaide A/Prof Ben Cazzolato joined the School of Mechanical Engineering in 2001. Prior to that he was an Royal Academy of Engineering Anglo-Australian Post-Doctoral Fellow at the Institute of Sound and Vibration Research at the University of Southampton, UK. His research and consulting career spans dynamic systems and control theory.
Member: Dr Paul Grimshaw The University of Adelaide ONC, HNC (Ministry of Defence, UK), BA Hons, (Leeds UK), PhD (Salford UK) Paul Grimshaw joined the University of Adelaide in 2009 as a SeniorLecturer after spending 10 years at the University of South Australiateaching Biomechanics, Anatomy and Statistics. Previously he has heldacademic positions at the Universities of Brunel, Edinburgh and Exeter inthe UK. His academic research interests focus on Biomechanics and theprevention of injury particularly knee instability, low back pain during liftingand injury in sports such as golf.
Member: A/Prof Eric Hu The University of Adelaide BE (Zhejiang U), ME (BSERI), PhD (Asian Institute of Tech), MIEA
A/Prof Eric Hu joined the School of Mechanical Engineering at theUniversity of Adelaide in 2009. Prior to this appointment he was anAssociate Professor at Deakin University since 1999. From 1993 to 1999,he was lecturer and senior lecturer at School of Engineering, Monash University. His academic and research career has largely focused onthermal and sustainable energy engineering areas.
Member: Mr Ian Brown The University of Adelaide BAppSc, MAppSc (University of Adelaide), MIEAust, CPEng, CMP
Ian Brown was a Lecturer in the School of Mechanical Engineering at the University of Adelaide until February 2012 when he was appointed as a Senior Research Fellow for the Energy Pipeline CRC at the University of Adelaide. His academic and research interests have been in the fields of materials, manufacturing, failure analysis and welding.
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Technical Committee Mr Aditya Khanna The University of Adelaide
Dr Adrian Orifici RMIT University
Dr Alex Ng The University of Adelaide
Prof Alexander Dumansky Institute of Machine Science (Russian Academy of Sciences)
A/Prof Amandeep Virk Virk The University of Queensland
A/Prof Andrei Kotousov The University of Adelaide
Dr Andrew Dixon BlueScope Steel Research
Prof Arcady Dyskin The University of Western Australia
A/Prof Ben Cazzolato The University of Adelaide
Dr Bill Daniel The University of Queensland
Dr Ching-Tai Ng The University of Adelaide
Prof Chun Wang RMIT University
A/Prof Colin Kestel The University of Adelaide
Dr Craig Willis The University of Adelaide
Mr Daniel Searson The University of Adelaide
Dr David Tawfik Tawfik Group
Prof Deric Oehlers The University of Adelaide
A/Prof Dianne Hesterman The University of Western Australia
Dr Edmund (Chin Kian) Liew The University of Queensland
Prof Elena Pasternak The University of Western Australia
A/Prof Eric Hu The University of Adelaide
Prof Filippo Berto Padua University, Italy
Dr Francis Rose DSTO Air Vehicles Division, Melbourne
A/Prof Gangadhara Prusty The University of New South Wales
Mr Ian Brown The University of Adelaide
A/Prof Ian Howard Curtin University
Dr John Costi Flinders University
Prof John Price Monash University
A/Prof Karu Karunasena The University of Southern Queensland
Dr Leonid Antanovskii DSTO, Adelaide
Prof Liangchi Zhang The University of New South Wales
Mr Lloyd Fletcher The University of Adelaide
A/Prof Martin Veidt The University of Queensland
A/Prof Nicole Kessissoglou The University of New South Wales
Dr Ningsheng Feng The University of New South Wales
Prof Nong Zhang The University of Technology Sydney
Dr Paul Grimshaw The University of Adelaide
A/Prof Philip Mathew The University of New South Wales
Dr Raj Das University of Auckland, New Zealand
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Technical Committee (Continued) A/Prof Reza Ghomashch The University of Adelaide
Prof Robert Randall The University of New South Wales
Dr Sabrina Vantadori University of Parma, Italy
Dr Sook-Ying Ho DSTO, Adelaide
Dr Stuart Wildy Flinders University
Ms Tandy Pok Delta-V Experts
Dr Timothy Coates
Prof Tony Kinloch Imperial College, United Kingdom
Prof Wingkong Chiu Monash University
Prof Yuris Dzenis University of Nebraska-Lincoln, United States of America
Keynote Speakers
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Professor Stephen Grano
New challenges in power, resource and mineral industries 10th of December, 9:20 – 9.45 am, Napier 102
Professor Stephen Grano is the Director of the Institute for Mineral and Energy Resources at the University of Adelaide since March 2010.
Stephen is an experienced and internationally recognized Metallurgical Engineer with nearly 30 years of postgraduate experience and works closely with the minerals and energy industries and has an excellent track record in successful technology transfer to industry. He has extensive leadership experience and capacity to shape large scale and innovative research initiatives involving multiple relationships which are both internal and external to the university environment. Stephen has an extensive and sustained success in obtaining grants playing a lead role in leadership, proposal formulation, and negotiation, and has forged a range of industry partnerships at national and international levels for more than 20 years.
22
Professor Bob Adams BSc(Eng), PhD, DSc(Eng), FIMechE, FInstP
Can we really predict accurately the strength of adhesively bonded joints? 10th of December, 1:00 – 1.45 pm, Napier 102
Professor Emeritus of the University of Bristol, Visiting Professor at the University of Oxford, UK and the Former Head of Department and Graduate Dean of Engineering at Bristol, Professor Adams received his PhD from Cambridge University on the subject of damping in metals in 1967, when he joined Bristol University. There, he set up groups on composites and adhesives, studying both static and dynamic behaviour. He pioneered the use of Finite Element Analysis for predicting the mechanical behaviour of bonded joints, particularly their strength.
In composites, his main interest was in the measurement and prediction of the damping and dynamic moduli of laminates. Starting from directly measured fibre and matrix behaviour, micro and macro mechanics theories were used to predict the dynamic properties of laminates, which were then carefully measured to complete the circle.
His work on composites and adhesives developed in parallel and his group recently studied compound adhesive joints for use at high and low temperatures, such as might be encountered by supersonic aircraft. The answer to the question of why real joints fail still eludes us, but very recent work has brought up some unusual evidence which might just solve the problem.
Recent work has also been on the subject of adhesive bonding in multimaterial lightweight structures for transport use. Bob has written and edited several books on adhesive joints, together with hundreds of papers in refereed journals and conferences. Currently he is joint editor in chief of the International Journal of Adhesion and Adhesives, which has the highest impact factor of all the international journals on adhesion.
23
Professor Tony Kinloch FREng FRS
The mechanics and mechanisms of fracture of nano-modified polymers 11th of December, 9:00 – 9.45 am, Napier 102
Professor Tony Kinloch is currently the Professor of Adhesion and Head of the Department of Mechanical Engineering at Imperial College London, UK. He leads the "Adhesion, Adhesives and Composites" Research Group and has published over two hundred and fifty patents and refereed papers in the areas of adhesion and adhesives, toughened polymers and the fracture of polymers and fibre-composites. He has written and edited seven books in these areas. Some fifty students have obtained their PhD under his supervision. He has been awarded the "Armourer's and Braziers Prize for Materials Science" from The Royal Society, the "Le Prix Dedale de la Societe Francaise d'Adhesion" from the French Adhesion Society, the "Hawkesley Gold Medal" of the Institution of Mechanical Engineers, the "Griffith Medal and Prize" and "Wake Medal" of the Institute of Materials, the Adhesion Society of Japan Award for "Distinguished Contributions to the Development of Adhesion Science and Technology" and the US Adhesion Society Award for "Outstanding Excellence in Adhesion Research". In 1997 he was elected a Fellow of the Royal Academy of Engineering (FREng) and in 2007 was elected a Fellow of the Royal Society (FRS).
24
Professor Nong Zhang
Passive and active hydraulically interconnected suspensions and their applications 11th of December, 1:00 – 1.45 pm, Napier 102
Professor Zhang is currently the Professor of Mechanical Engineering in the School of Electrical, Mechanical and Mechatronic Systems, University of Technology, Sydney, Australia. For more than 25 years, Professor Zhang has been focused on fundamental research on vibration theory, multi-body system dynamics and its applications in complex machines and vehicular systems. His research has involved both substantial theoretical and experimental investigations and in particular, he has acquired extensive research experience in vibration of rotating machines, engines and integral vehicle powertrains.
He has recently focused on the dynamics of large mechanical systems consisting of many complex components, and developed advanced models and numerical schemes for simulating gear shift in powertrains with AT, CVT and DCT and for the dynamic analysis of vehicle powertrains of conventional vehicles, EVs and HEVs. He has also developed the design theories and application prototypes of passive and active hydraulically interconnected suspensions for vehicle handling and rollover prevention. He has been successful in pursuing applied research in multiple disciplines exemplified by the projects on the dynamics of implanted VentrAssistTM heart pump, novel suspensions and dual clutch transmissions.
25
Dr. Sabrina Vantadori M.Sc (Laurea), Ph.D.
Stress-intensity factors and fatigue growth for surface cracks 12th of December, 9:00 – 9.45 am, Napier 102
Dr. Vantadori is currently Assistant Professor of Structural Mechanics at the Dept of Civil and Environmental Engineering & Architecture, University of Parma (Italy). She graduated with a M.Sc. (Laurea) in Civil Engineering at the University of Parma (Italy) before moving on to do her Ph.D. in Stuctural Mechanics at the University of Bologna (Italy) and working as a Post-Doctoral Fellow at the University of Parma. Her Ph.D. thesis was on the “Mechanical behaviour of metallic structural components with notches and cracks” on which she worked closely with Professor Andrea Carpinteri.
Her research has been focused around the theoretical and numerical modelling of materials and structures, Fracture Mechanics of engineering materials and structures, reinforced and fibre-reinforced concrete structures as well as time-variable loadings (fatigue).
Dr Sabrina Vantadori has been a Member of the Organizing Committees of several International Conferences since 2003. She is the author of about 80 scientific publications. She is going to guest edit a Special Issue of the International Journal of Fatigue containing selected papers presented at the 4th International Conference on Crack Paths (CP 2012), Gaeta (Italy), 19-21 September 2012), and to co-chair the 13th ASTM/ESIS Symposium on Fatigue and Fracture, Jacksonville (USA), 13-15 November 2013.
26
Professor Yuris Dzenis PhD (Physics and Mechanics of Polymers), PhD (Aerospace and Mechanical Engineering)
Design, nanomanufacturing, and mechanics of novel superstrong/Tough continuous nanofibers for next generation supernanocomposites 12th of December, 1:00 – 1.45 pm, Napier 102
Dr. Yuris Dzenis is a McBroom Professor of Engineering at University of Nebraska-Lincoln, US. He received his PhD in Physics and Mechanics of Polymers from Latvian Academy of Sciences and another PhD in Aerospace and Mechanical Engineering from the University of Texas.
His research interests are in design, precision manufacturing, characterization, and modeling of advanced nanomaterials and composites.He has been a PI/PD on over 20 federal nanotechnology and advanced materials projects from NSF, AFOSR, ARO, ONR, and DARPA and developed unique interdisciplinary Advanced Nanomaterials and Nanomanufacturing Laboratories. Prof. Dzenis has introduced and developed several nanomanufacturing and hybrid manufacturing technologies to produce advanced nanomaterials.He has introduced a concept of nanoreinforcement of interfaces and pioneered development of cost-effective delamination resistant nanoengineered structural composite laminates.
Dr. Dzenis has been an invited plenary speaker at numerous national and international conferences on nanotechnology, materials, mechanics, NDE, and composites. He has written invited field-defining perspectives on continuous nanofibers and structural nanocomposites for Science. He is a Graduate Fellow in the PhD fields of Engineering Mechanics, Chemical and Materials Engineering, and Biomedical Engineering.
Keynote Abstracts
28
Can we really predict accurately the strength of adhesively bonded joints?
Robert D. Adams1,2* and E. F. Karachalios2
1 Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK 2 Department of Mechanical Engineering, University of Bristol, Queen’s Building, University Walk, Bristol BS8 1TR, UK
*Corresponding author. Email: [email protected] Adhesive bonding is a very attractive joining technique offering great flexibility to the designer engineer. However, designing adhesively bonded joints that could carry significant loads has been encumbered by the lack of a suitable strength predictor. There is no universally applicable failure criterion that can predict failure in a variety of joint configurations (material, geometry, loading). This is because the failure of the bonded joints depends on many different parameters and the way they interact with each other. There is therefore a need to understand the mechanisms of failure and also the parameters that affect the strength of bonded joints. This will enable accurate strength predictions so that the designer can make use of all the advantages that the adhesives can provide. Success will come from an astute combination of the observation of failed joints, mathematical modelling, and material characterisation. The objective of this paper is to review the various methods available and to indicate which approaches are likely to be successful. To narrow the investigation, only high strength adhesives such as epoxies will be discussed. The adherends range from ductile metals to high strength steels with limited ductility. This is because different failure parameters exist with elastic and with ductile metals. Adherends made from composite materials such as carbon fibre reinforced plastics (CFRP) present a special problem as the joint strength is strongly affected by the low transverse strength of the CFRP. The single lap joint (SLJ) configuration was analysed experimentally and theoretically using the finite element method (FEM). Joints in many different geometric and material configurations were tested in tension. Geometric parameters such as the overlap length, the adherend thickness, together with material parameters such as the adherend and adhesive stress-strain behaviour, were all investigated in the current work. The mechanisms and modes of failure were observed for different cases, and positions of damage initiation were identified. Failure patterns were correlated with the stress-state in the joints, and also with the associated failure mechanisms. A failure prediction methodology was proposed and good correlation between the experimental and F.E predicted results for a variety of joint configurations was obtained. A simple but accurate predictive theory was developed based on the FE predictions and careful experimental observations.
Keywords: single lap joints, failure prediction, finite element analysis, adhesive plasticity, adherend plasticity, pressure dependent yield criterion, overlap length
29
The mechanics and mechanisms of fracture of nano-modified polymers
Anthony J. Kinloch*1, 2, T.H. Hsieh1, J. Sohn Lee1, K. Masania1 and A.C. Taylor1.
1 Imperial College London, Department of Mechanical Engineering, South Kensington Campus, London SW7 2AZ, UK. 2 The University of Sydney, School of Aerospace Mechanical & Mechatronic Engineering, Sydney, NSW 2006, Australia.
*Corresponding author. Email: [email protected]
The present paper considers the mechanical, fracture and cyclic-fatigue properties of four different epoxy polymers containing 0, 10 and 20 wt% of well-dispersed silica nanoparticles [1-6]. Firstly, it was found that, for any given epoxy polymer, their Young’s modulus steadily increased as the volume fraction, vf, of the silica nanoparticles was increased. Modelling studies showed that the measured moduli of the different silica-nanoparticle filled epoxy-polymers lay between upper-bound values set by the Halpin-Tsai and the Nielsen ‘no-slip’ models, and lower-bound values set by the Nielsen ‘slip’ model; with the last model being the more accurate at relatively high values of vf. Secondly, the presence of silica nanoparticles always led to an increase in the toughness of the epoxy polymer. However, to what extent a given epoxy polymer could be so toughened was related to structure/property relationships which were governed by (a) the values of glass transition temperature, Tg, and molecular weight, Mc, between cross-links of the epoxy polymer, and (b) the adhesion acting at the silica-nanoparticle/epoxy-polymer interface. Thirdly, the two toughening mechanisms which were operative in all the epoxy polymers containing silica nanoparticles were identified to be (a) localised shear-bands initiated by the stress concentrations around the periphery of the silica nanoparticles, and (b) debonding of the silica nanoparticles followed by subsequent plastic void-growth of the epoxy polymer. Finally, the toughening mechanisms have been quantitatively modelled [7,8] and there was good agreement between the experimentally measured values and the predicted values of the fracture energy, Gc, for all the epoxy polymers modified by the presence of silica nanoparticles. The modelling studies have emphasised the important roles of the stress versus strain behaviour of the epoxy polymer and the silica-nanoparticle/epoxy-polymer interfacial adhesion in influencing the extent of the two toughening mechanisms, and hence the overall fracture energy, Gc, of the nanoparticle-filled polymers.
References
1. A.J. Kinloch, J.H. Lee, A.C. Taylor, S. Sprenger, C. Eger and D. Egan, 2003, "Toughening structural adhesives via nano- and micro-phase inclusions", Journal of Adhesion, vol. 79, pp. 867-873.
2. A.J. Kinloch, R. Mohammed, A.C. Taylor, C. Eger, S. Sprenger and D. Egan, 2005, "The effect of silica nano particles and rubber particles on the toughness of multiphase thermosetting epoxy polymers, Journal of Materials Science, vol. 40, pp. 5083-5086.
3. S.Q. Deng, J.N. Zhang and L. Ye, 2009, “Halloysite-epoxy nanocomposites with improved particle dispersion through ball mill homogenisation and chemical treatments”, Composites Science and Technology, vol. 69, pp. 2497-2505.
4. T.H. Hsieh, A.J. Kinloch, K. Masania, J. Sohn Lee, A.C. Taylor and S. Sprenger, 2010, "The toughness of epoxy polymers and fibre composites modified with rubber microparticles and silica nanoparticles", Journal of Materials Science, vol. 45, pp. 1193-1210.
5. H.Y. Liu, G.T. Wang, Y.W. Mai, and Y. Zeng, 2011, " On fracture toughness of nano-partilce modified epoxy", Composites Part B: Engineering, vol.42, pp. 2170-2175.
6. B.B. Johnsen, A.J. Kinloch, R.D. Mohammed, A.C. Taylor and S. Sprenger, 2007, "Toughening mechanisms of nanoparticle-modified epoxy polymers", Polymer, vol. 48, pp. 530-541.
7. Y. Huang and A.J. Kinloch, 1992, "Modelling of the toughening mechanisms in rubber-modified epoxy polymers. Part II: A quantitative description of the microstructure-fracture property relationships", Journal of Materials Science, vol. 27, pp. 2763-2769.
8. T.H. Hsieh, A.J. Kinloch, K. Masania, A.C. Taylor and S. Sprenger, 2010, "The mechanisms and mechanics of the toughening of epoxy polymers modified with silica nanoparticles", Polymer, vol. 51, pp. 6284-6294.
30
Passive and active hydraulically interconnected suspensions and their applications Nong Zhang1*, Wade A. Smith2 and Chun Wang1
1 School of Mechanical and Mechatronic Engineering, University of Technology, Sydney, NSW 2007 2 School of Mechanical and Manufacturing Engineering, University of New South Wales, NSW 2007
*Corresponding author. Email: [email protected] Abstract: In this paper, after giving a brief literature survey introduction, a description is presented of the mechanism and modelling of system dynamics in the frequency domain of a vehicle fitted with a hydraulically interconnected suspension (HIS) using a 4-DOF half-car model. A set of coupled, frequency-dependent equations, which govern the dynamics of the integrated half-car system, are derived and the applications of these equations to both free and forced vibration analysis are presented. The experimental validation of the analytical results of the free and forced vibrations of the roll-plane half-car is provided. Simulation results obtained for the roll-plane half-car fitted with a hydraulically interconnected suspension are compared with those of a conventional suspension. A brief introduction is given on a 9-DOF model of a vehicle fitted with an HIS and simulations of a fishhook manoeuvre to assess its handling performance. The fluid subsystem of the HIS is modelled using a nonlinear finite-element approach, resulting in a set of coupled, first-order nonlinear differential equations, which describe the dynamics of the integrated mechanical and hydraulic vehicle system. Both the simulation and test results indicate that, in general, the HIS-equipped vehicle possesses superior handling performance, as measured by the sprung mass roll angle, roll rate, roll acceleration, lateral acceleration and the vehicle’s Rollover Critical Factor. A brief introduction is also presented on the recent development of the motion-mode energy method for classifying vehicle body-wheel motions into several motion-modes, according to their modal properties, and quantifying the contribution of each motion-mode by its energy intensity in real time. The motion-mode energy and mode contribution ratio are used to determine the control priority on the control of the most dominating motion-mode. Simulation results are obtained to illustrate the applicability of the proposed methods. Finally, the paper very briefly introduces the semi-active and active HIS, including the mechanism of active HIS hardware. The preliminary experimental results on the active HIS are also given to show the applicability of the novel active HIS mechanism and controllers. Furthermore, discussions are provided on the current issues encountered in applications of passive and active HIS and the future research challenges. Concluding remarks are given on the key findings obtained from the conducted studies on the passive and active HIS. Keywords: interconnected suspension; vehicle dynamics; rollover prevention; vehicle handling; vehicle system parameter identification.
31
Stress-Intensity factors and fatigue growth for surface cracks
Andrea Carpinteri and Sabrina Vantadori*
Department of Civil and Environmental Engineering and Architecture, University of Parma, Parco Area delle Scienze 181/A, 43124 Parma, Italy *Corresponding author. Email: [email protected] Abstract: The structural safety of metallic components, such as bars, plates, pipes and shells, should be assessed by also taking into account the influence of defects, which can greatly affect the reliability of these components, particularly when they are subject to cyclic loading. During last decades, the problem of cracked solids has been extensively analised by the Authors, by considering: a)round bars, such as bolts, screws, pins, reinforcements, tendons for prestressed concrete structures, supports in suspension and stayed bridges; b) double-curvature shells (having to distinct principal curvature radii) such as pressure vessels, pipe elbows and fuel tanks. As has experimentally been observed, elliptical-arc surface cracks may grow through the cross-sections or the thicknesses of the above components, reducing their strength and provoking catastrophic failures. Therefore, accurate stress analyses have to be performed. Assuming a linear elastic behaviour of the material, the stress field near the crack front can be represented by the stress-intensity factor (SIF). The calculation of the SIF along the front of both almond and sickle-shaped surface cracks can be carried out through three-dimensional finite element analyses together with the one-quarter point displacement method. Different Mode I loading conditions are analysed: tension, bending, rotary bending, eccentric axial loading. Further, elementary stress distributions acting on the crack faces have been analysed, and the related results have been used to approximate evaluations of the SIF under complex stresses (for instance thermal and residual stresses), by also employing the superposition principle and the power series expansion of such complex stresses. The above structural components frequently present geometrical discontinuities (as changes in crosssection sizes, fillets, ribbers, etc) or are obtained by assembling different parts jointed together through welding processes. Such geometrical variations, often modelled by means of notches, are preferential sites for crack nucleation, due to the stress concentration. Since the stress field can be quite different from that found out in the unnotched structural components previously introduced with an identical surface flaw, the SIF is computed by taking into account the notch effect, for both semi-circular and V-shaped notches. An elliptical-arc part through crack is then assumed to be located at the notch root. The problem of a flawed solid becomes more complex in the case of simultaneous presence of more than one crack: as a matter of fact, the cracks could interact and give rise to SIF values higher than those experienced by the body with only one crack. Such a case has been studied by the Authors for a plate containing twin coplanar flaws. Finally, the fatigue behaviour is evaluated using the above SIF results. In particular, crack paths, crack growth rate curves and crack front evolutions are determined through a numerical procedure, based a two-parameter theoretical model proposed by the first Author. The results determined by the present authors are compared with those available in the literature. Keywords: finite element analysis, linear elastic, Mode I, SIF.
32
Design, nanomanufacturing, and mechanics of novel superstrong / tough continuous nanofibers and next generation supernanocomposites Yuris Dzenis* Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA
*Corresponding author. Email: [email protected]
Abstract: Development of advanced fibers and composites in the second half of the 20th Century has revolutionized the field of structural materials. However, new fiber development has been mostly evolutionary in the last two decades. It is well-known that fiber strength increases with their diameter decrease. However, conventional mechanical spinning techniques cannot produce fibers with diameters smaller than about two micrometers. Most reinforcing fibers are many times that diameter due to trade-offs between cost and manufacturability. Recently, there is a growing interest in using nanotechnology to further improve fiber properties. Carbon nanotubes have been used as nanoreinforcement in polymer and carbon fibers and pure CNT fibers have been produced by several techniques. However, the formidable issues with CNT alignment, high volume fraction, interfacial stress transfer, and the potential health problems are yet to be resolved and no CNT superfiber has yet been demonstrated. This presentation will review the state-of-the-art and recent breakthroughs in the author’s group on an alternative class of high-performance nanomaterials, i.e. continuous nanofibers produced by electrospinning [1]. Recent progress on nanomanufacturing of individual nanofilaments will be discussed. Prospects of modeling-based precision nanomanufacturing of complex hierarchical 2D and 3D nanofilamentary architectures will be evaluated [2,3]. Examples of high-performance polymer, carbon, and ceramic nanofibers and nanofibers with structure templated with carbon nanotubes will be presented [4]. Results of pioneering nanomechanics testing of several types of individual nanofibers and the discovered unusual nanoscale size effects will be presented [5]. First simultaneously superstrong / tough continuous nanofilament for structural applications will be reported. Mechanics of nanofiber assemblies and networks will be analyzed based on experiments and simulation. Possibility of further significant fiber strengthening and toughening by controlled lateral interaction between nanofilaments will be demonstrated. Recent breakthroughs on nanofiber-reinforced supernanocomposites (defined as nanocomposites exceeding the properties of conventional advanced composites [6,7]) will be presented and discussed. Static, fatigue, and dynamic impact behavior of these novel nanostructured materials will be reviewed. Recommendations for the cost-effective designs of structural nanocomposites for near-to-medium term applications will be formulated. Brief overview of other nanofiber uses will also be given, including applications in biomedicine and sensors/actuators.
Keywords: continuous nanofibers, electrospinning, mechanical properties, modelling-based nanomanufacturing, structural nanocomposites, strength, toughness
References 1. Y. Dzenis, “Spinning Continuous Nanofibers for Nanotechnology”, Science, 304, 2004, 1917-1919
2. X. Wu, Y. Salkovskiy, and Y. Dzenis, “Modeling of Solvent Evaporation from Polymer Jets in Electrospinning”, Applied Physics Letters, 2011, Vol. 98, 223108
3. L. Liu and Y. Dzenis, “Simulation of Electrospun Nanofiber Deposition on Stationary and Moving Substrates”, Micro & Nano Letters, 2011, Volume 6, Issue 6, pp. 408–411
4. D. Papkov, A.M. Beese, A. Goponenko, Y. Zou, M. Naraghi, H.D. Espinosa, B. Saha, G.C. Schatz, A. Moravsky, R. Loutfy, S.T. Nguyen, Y. Dzenis, “Extraordinary Improvement of Graphitic Structure of Continuous Carbon Nanofibers Templated with Double Wall Carbon Nanotubes”, ACS Nano, 2012, in print
5. D. Papkov, Y. Zou, M.N. Andalib, A. Goponenko, S.Z. Cheng, Y. Dzenis, “Dramatic Simultaneous Improvements in Strength, Modulus, and Toughness in Ultrafine Polymer Nanofibers”, submitted
6. Y. Dzenis, "Structural Nanocomposites", Science, 2008, 319, 419-420
7. R.O. Ritchie; and Y. Dzenis, "The Quest for Stronger, Tougher Materials", Science, 2008, 320, 448
Presented Abstracts
34
Session 1: Fracture Mechanics I Paper No: 149 Time: 1020 - 1040 Venue: Napier G03 Chair: Prof. Liangchi Zhang Presenter: Jesús Toribio
Evolution of compliance in round bars subjected to tensile and bending fatigue cracking
Jesús Toribio1*, Juan-Carlos Matos2, Beatriz González1 and José Escuadra2
1 Department of Materials Engineering, University of Salamanca, E.P.S. Zamora (Spain) 2 Department of Computing Engineering, University of Salamanca, E.P.S. Zamora (Spain) *Corresponding author. Email: [email protected]
Abstract: The aim of this paper is to obtain how dimensionless compliance evolves in cracked cylindrical bars subjected to cyclic tension loading or cyclic bending loading with different initial crack geometries (crack depths and aspect ratios). To this end, a computer application (in the Java programming language) that calculates the crack front’s geometric evolution and the dimensionless compliance was made by discretizing the crack front (characterized with elliptical shape) and assuming that every point advance perpendicular to the crack front according to the Paris law, and using a three-parameter stress intensity factor (SIF). The results show that in fatigue crack propagation, relative crack depth influences more on dimensionless compliance than the aspect ratio, because the crack front tends to converge when the crack propagates from different initial geometries, showing greater values for cyclic tension loading than for cyclic bending loading. Furthermore, during fatigue crack growth, materials with higher values of the Paris parameter m produce slightly greater dimensionless compliance and a better convergence between the results for straight and circular initial crack.
Keywords: dimensionless compliance, fatigue crack growth, numerical modelling, cracked round bar, Paris law.
35
Session 1: Fracture Mechanics I Paper No: 170 Time: 1040 - 1100 Venue: Napier G03 Chair: Prof. Liangchi Zhang Presenter: Rhys Jones
The short crack anomaly in aerospace structural materials Rhys Jones* and Susan Pitt
Centre of Expertise in Structural Mechanics, Department of Mechanical and Aeronautical Engineering, Monash University, Clayton, Vic 3800, Australia. *Corresponding author. Email: [email protected]
Abstract: The Royal Australian Air Force approach to the management of fatigue cracking in combat and trainer aircraft makes use of the “lead crack” concept. In this approach crack growth is assumed to initiate from small naturally occurring defects/discontinuities with dimensions of approximately 10 μm and growth is assumed to commence from day one. As a result, for certification purposes, we need to address the so called short crack anomaly, whereby for a given ΔK the crack growth rate (da/dN) is significantly greater for short cracks than it is for long cracks. In this paper we reveal that this anomaly vanishes if da/dN is represented as a function of (ΔK – ΔKthr), where ΔKthr is best thought of as an apparent threshold. We then show that for operational aircraft the da/dN versus ΔK curve is an amalgam of the short and long crack growth curves. From this it follows that existing test procedures used to establish the effect of composites repairs on fleet aircraft overestimates their effect. We also show that that the growth of cracks from small naturally occurring defects exhibit little, if any, R ratio effects.
Keywords: short cracks, R ratio, crack closure, crack patching, lead cracks.
36
Session 1: Fracture Mechanics I Paper No: 005 Time: 1100 - 1120 Venue: Napier G03 Chair: Prof. Liangchi Zhang Presenter: Andrei Kotousov
Coupled fracture modes in three-dimensional fracture mechanics Andrei Kotousov1*, Paolo Lazzarin2 and Filippo Berto2
1 School of Mechanical Engineering, the University of Adelaide, South Australia, Australia 2 Department of Management and Engineering, the University of Padova, Italy
*Corresponding author. Email: [email protected]
Abstract: Shear and anti-plane loadings of an elastic plate with a through-the-thickness crack generate various singular stress states: primary fracture modes (conventional fracture mode II and III), corner singularities, and coupled fracture modes. Two latter 3D singular states are largely ignored in theoretical and experimental investigations as well as in the current standards and failure assessment codes. It is often implicitly assumed that all three-dimensional effects are negligible and the actual three-dimensional stress state can be adequately approximated by stress components found, for example, from the corresponding classical solutions of the plane theory of elasticity. In this paper we provide an overview of recent 3D studies carried out by the authors, which demonstrate that the account for these coupled modes can totally change the classical view of many fracture phenomena. In particular, this relates to a generation of the coupled fracture modes by shear and anti-plane loading with KII = 0 and KIII = 0, respectively. In these cases the coupled fracture modes dominate the near crack tip stress field and are capable to initiate brittle fracture. In addition, the intensities of the coupled modes are significantly influenced by the thickness of the plate, the effects of which are also disregarded in the classical Linear-Elastic Fracture Mechanics.
Keywords: brittle fracture, coupled fracture modes, crack, finite element modelling, scale effect, stress singularities.
37
Session 1: Fracture Mechanics I Paper No: 144 Time: 1120 - 1140 Venue: Napier G03 Chair: Prof. Liangchi Zhang Presenter: Janet Wilson
Modelling the complex manufacturing history of a pipework joint, assessment of its through life creep-fatigue and calculation of the J-Integral using finite element based methods Mark J. Stevens1, Dr Roger J. Dennis1, Ian J.M. Bottomley1, Dr Janet Wilson1* and Dr R. A. W. Bradford2 1 Frazer-Nash Consultancy Limited, 1 Trinity Street, College Green, Bristol, BS1 5TE, UK 2 EDF Energy Nuclear Generation Limited, Barnett Way, Barnwood, Gloucester, GL4 3RS, UK, rick.bradford@edf energy.com *Corresponding author. Email j.wilson@fncaustralia .com.au
Abstract: The work reported in this paper describes a simulation of the manufacture, through-life operation and limiting defect size assessment of a pipework joint in a nuclear powerplant boiler. The objective of this work is to understand the critical factors that influence the integrity of the joint in-service and support accurate predictions of service life. This work differs from typical structural integrity assessments in that advanced modelling techniques have been used through-out the assessment process and include detailed simulations of the manufacturing process, a simulation of the entire in-service operating history including predictions of creep-fatigue damage and cracked body analysis to determine limiting defect sizes.
The residual stresses generated during manufacture may adversely affect the critical defect sizes for the pipework joint. However, the complex geometry and loading complicate the assessment of the cracked body. Therefore, a finite-element analysis representing the cracked body has been carried out on the pipework joint to evaluate the J-Integrals at the locations of interest and hence calculate the critical defect sizes. The analysis considers the residual stresses determined from the finite-element analysis of the manufacturing processes.
Keywords: cracked body mesh, creep-fatigue damage, finite element analysis, J-Integral, residual stress.
38
Session 1: Fracture Mechanics I Paper No: 232 Time: 1140 – 1200 Venue: Napier G03 Chair: Prof. Liangchi Zhang Presenter: William J. T. Daniel
An Investigation on rail squat prediction due to rolling contact fatigue Mohammadali Farjoo1, William J. T. Daniel2*, Paul A. Meehan3 1 School of Mechanical and Mining Engineering, University of Queensland, St Lucia Campus, 4072. 2 School of Mechanical and Mining Engineering, University of Queensland, St Lucia Campus, 4072. 3 School of Mechanical and Mining Engineering, University of Queensland, St Lucia Campus, 4072. *Corresponding author. Email: [email protected]
Abstract: A rail squat is a rolling contact fatigue (RCF) crack that appears on a rail surface as a depression, due to plastic flow above the crack, and which grows from a surface flaw to almost 5 mm below the running surface, in both the direction of travel, and the opposite direction. This paper investigates parameters that affect initiation and propagation of squats. The crack develops under mixed fracture modes. A 3D finite element (FE) model of a rail is created and validated with former models and experiments. While the wheel-rail contact load moves over the crack, the equivalent stress intensity factor (SIF) at the crack tip changes. Due to the curved geometry of the rail head surface and elastic foundation effects of the rail support, the opening mode and shear modes are found to behave differently to predictions of a former model. Parameters that affect squat growth (i.e. internal pressure due to rain water in the crack, longitudinal and lateral traction ratios, the elasticity of the track support, residual stresses, and crack geometry), are considered in the 3D FE model. SIFs at the crack front, and angles of crack growth are obtained, varying these parameters. In addition, a database of 4900 locations over 260 Km is used to assess the influence and importance of rail type, rail age, sleeper type, and radius of the rail curvature on the presence of squats. Mixed mode analysis is done to find how these parameters may increase the risk of squat formation.
Keywords: contact fatigue, crack propagation, elastic foundation effects, finite element method, mixed model, rolling white etching layer, squat, stress intensity factor, water entrapment.
39
Session 2: Dynamics I Paper No: 120 Time: 1020 – 1040 Venue: Napier G04 Chair: Prof. Nong Zhang Presenter: Robert B. Randall
Bearing fault simulation using finite element model updating and reduction techniques Lav G. Deshpande1*, Nader M. Sawalhi2 and Robert B. Randall3 1,3 School of Mechanical and Manufacturing Engineering, University of New South Wales, Australia 2 School of Mechanical Engineering, Prince Mohammad Bin Fahd University, Kingdom of Saudi Arabia *Corresponding author. Email: [email protected]
Abstract: Simulation provides an effective method to generate vibration signals in the presence of machine faults such as in gears and bearings. Lumped parameter models (LPMs) and the LPM combined with a reduced finite element (FE) model of the casing were previously used to simulate localised and extended bearing faults in the inner and outer race. The analysis of the vibration signals based on the above techniques clearly indicated the presence of localised inner and outer race faults through envelope analysis in a high frequency band. However, the simulated results showed poor spectral matching over a wide frequency range when compared with the test results. There were also discrepancies in the low frequency region where extended faults in the outer and/or inner race interact with and modulate gearmesh frequencies. This paper describes FE-Test correlation wherein the FE model of the gearbox casing is updated based on experimental modal analysis prior to the model reduction. The updated casing model is subsequently reduced using the Craig Bampton method of component mode synthesis subject to the frequency range of interest. The greatly reduced mass and stiffness matrices are imported into a simulation model developed earlier which has the capability of simulating time-varying stiffness nonlinearities and geometric faults for both gears and bearings. This paper mainly highlights the simulation of vibration signals in the presence of localised inner race faults. The simulated results with the updated model are compared with the measured signals.
Keywords: bearing faults, component mode synthesis, finite element analysis, lumped parameter model, model updating, simulation.
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Session 2: Dynamics I Paper No: 022 Time: 1040 – 1100 Venue: Napier G04 Chair: Prof. Nong Zhang Presenter: Minli Yu
Identification of foundations in rotating machinery using modal parameters Minli Yu1*, Ningsheng Feng1 and Eric J. Hahn1 1 School of Mechanical & Manufacturing Engineering, the University of New South Wales, Australia *Corresponding author. Email: [email protected]
Abstract: An attractive approach for identifying the dynamic stiffness of a rotating machinery foundation is to identify the relevant modal parameters of an equivalent foundation, using for the identification the motion measurements of the rotor and the foundation at the bearing supports. Earlier procedures required the identification of all assumed vibrating modes, even if the highest assumed mode frequency turned out to be well outside the operating speed range of interest. This paper overcomes such problems by enhancing the earlier identification technique to solve accurately for fewer modes than actually assumed; essentially by generalising the technique to be able to handle rectangular modal matrices. Numerical experiments show that this enhanced technique allows one to assume more degrees of freedom than actually necessary, yet still identify all the relevant vibration modes while ignoring unnecessary ones. The new identification procedure is robust in that good equivalent foundations are identified even when the measurement data is truncated to two digits and is therefore likely to be applicable in the field.
Keywords: identification, modal parameters, rotor foundations.
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Session 2: Dynamics I Paper No: 104 Time: 1100 – 1120 Venue: Napier G04 Chair: Prof. Nong Zhang Presenter: Jonny Latuny
A bearing fault classifier using Artificial Neuro-Fuzzy Inference System (ANFIS) based on statistical parameters and Daubechies wavelet transform features Jonny Latuny1* and Rodney D. Entwistle2
1,2 Department of Mechanical Engineering, Curtin University, Perth Western Australia *Corresponding author. Email: [email protected]
Abstract: This paper presents an investigation process in building a bearing fault classifier based on wavelet coefficients and statistical parameter features. The building process starts by processing raw vibration data that was acquired from a bearing test rig. The data acquisition process was carried out for both normal (fault-free) and fault operation of a double row self-aligning ball bearing. Two accelerometers were used to collect the vibration data. One was attached near the bearing under investigation and the other was attached at one of the shaft support bearing of the test rig. The raw data was then processed to extract the statistical parameters (i.e., kurtosis, RMS, variance, standard deviation). Further, the same data was processed using a wavelet transform employing Daubechies wavelet filter to produce wavelet coefficients and their energy levels. The features generated from statistical parameters and wavelet transform scheme were then used to train an Artificial Neuro-Fuzzy Inference System (ANFIS). In order to reduce the number of rules generated during the training process, only two inputs were used for the purpose of building the classifier. The selection of the most influential inputs for the training process of the ANFIS is achieved through the use of the ANFIS built in capability of selecting the best correlation of two inputs towards one target output which best represents the bearing operating condition. The process of selecting the most influential inputs-output combination was carried out using an extensive computation to obtain the best related two inputs, out of the six inputs available. The number of input-output combinations tested was 720, equal to the total of six input permutations. In the search for the best combination of inputs-output, the possible application between the combination of statistical parameters, wavelet coefficients and wavelet’s level of energy were investigated extensively in order to obtain the best classifier for bearing fault diagnosis. The ANFIS was then implemented to capture the input-output relation of the selected inputs to generate a suitable classifier that could be used to classify bearing operating condition. The classifiers generated were then tested to evaluate their ability and accuracy in predicting faulty bearing operating conditions. The result showed that a bearing fault classifier produced by using ANFIS through the proposed combined features of statistical parameters and Daubechies wavelet transform is promising as a bearing fault classifier.
Keywords: ANFIS, bearing fault classifier, Daubechies wavelet, diagnosis, statistical parameters, wavelet energy level.
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Session 2: Dynamics I Paper No: 106 Time: 1120 – 1140 Venue: Napier G04 Chair: Prof. Nong Zhang Presenter: Majed Masmali
Correlation of vibration and cutting forces in thin-walled machining Majed Masmali*, Huaizhong Li and Philip Mathew
School of Mechanical and Manufacturing Engineering, The University of New South Wales UNSW, Sydney, NSW 2052, Australia *Corresponding author. Email: [email protected]
Abstract: The lack of stiffness of thin-walled parts results in easy deflection under the cutting forces during the milling process. In this case, it is important to predict the cutting forces of milling thin-walled sections so that the wall sections are maintained at high accuracy. The prediction and analysis of cutting forces could play an essential role to select the cutting conditions, tooling and the system of machining used. Furthermore, the prevention of vibration, chatter, deformation, dimensional error and the maintenance of stable conditions of machining can be obtained by predicting the cutting forces. Many researchers have taken this topic into account and applied the theoretical concepts, simulation and other technical approaches to predict the cutting forces during machining operations so that good machining results can be obtained.
In this paper a methodology is developed to correlate the vibrational characteristics of the cutting process with the forces developed by the process. If this correlation exists then it is possible to develop a modelling approach to determine the characteristics of the thin walled sections can be determined. The work that will be described in this paper will present a technique to correlate the data and the use of the data for the development of the modelling approach. The experimental set-up and procedure will be presented and discussed. From this information it will be shown which characteristics can be correlated. Finally the feasibility of the process will be discussed.
Keywords: correlation, cutting forces, machining, thin-walled, vibration.
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Session 2: Dynamics I Paper No: 240 Time: 1140 – 1200 Venue: Napier G04 Chair: Prof. Nong Zhang Presenter: Wade A. Smith
Cepstrum-based operational modal analysis: regeneration of frequency response functions Robert B. Randall1 and Wade A. Smith1* 1 School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: This paper discusses the regeneration of frequency response functions (FRFs) based on a previously-proposed cepstrum-based operational modal analysis (OMA) technique. OMA differs from experimental modal analysis (EMA) in that it seeks to determine a structure’s dynamic characteristics from response-only measurements, without precise knowledge of excitation forces. Response measurements, however, comprise both excitation and transmission path effects, which must be separated before the structural properties can be determined. The method employed in this paper achieves source-path separation with the cepstrum, which is able to deal with ‘frequentially smooth’ (not just frequentially white) inputs. After separation, the poles and zeros of the transfer function can be obtained by curve-fitting the transfer path cepstrum. But the FRF regenerated from these poles and zeros corresponds to a truncated model of the system, covering only a limited frequency range. The out-of-band poles and zeros affect the magnitude and phase of the in-band FRFs, and this distortion must be corrected in the FRF regeneration process. This paper focuses on that correction using data from a steel beam experiment. To do this, an ‘equalisation curve’ is used, based on a comparison of the regenerated FRF with a ‘reference FRF’, found with EMA or FEM techniques. The paper proposes a polynomial-fit approach to obtain the equalisation curves, resulting in excellent agreement between measured and OMA-regenerated FRFs. The techniques outlined in the paper have a number of potential applications, particularly in the fault diagnostics and structural health monitoring fields, where damage is often detectable by changes in the structure’s FRFs.
Keywords: cepstrum, frequency response function (FRF), modal analysis, operational modal analysis (OMA), response measurement, source-path separation.
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Session 3: Bio-Mechanics I Paper No: 082 Time: 1020 – 1040 Venue: Napier 102 Chair: Dr. Paul Grimshaw Presenter: Rami M.A Al-Dirini
A subject-specific model of human buttocks and thighs in a seated posture Rami M.A Al-Dirini1,2*, Matthew P. Reed3,4, Gunther Paul5 and Dominic Thewlis6,7 1 Mawson Institute, University of South Australia, Adelaide 2School of Advanced Manufacturing & Mechanical Engineering, University of South Australia, Adelaide 3 University of Michigan Transportation Institute, University of Michigan, United States of America 4 Center for Ergonomics, Industrial and Operations Engineering, University of Michigan 5 School of Public Health and Social Work, Queensland University of Technology, Australia 6 Sansom Institute for Health Research, University of South Australia, Adelaide 7 School of Health Sciences, University of South Australia, Australia *Corresponding author. Email: [email protected] Abstract: Finite element analyses of the human body for seat interaction simulation require accurate and precise prediction of the tissue-level response. To achieve this, the human anatomy must be represented with high fidelity[1, 2]. Current practices for constructing subject-specific models based on magnetic resonance images (MRI) in supine postures have reduced the error in the geometric representation of subjects’ anatomy relative to reconstructions based on cadaveric data from previous studies. Nonetheless, the significant differences in bone orientation and soft-tissue contour between seated and supine postures create a need for data obtained in postures more similar to the application posture [2, 3]. In this study, we present a novel method for creating digital human models based on seated MR data. An adult-male volunteer was scanned in a simulated driving posture using a positional MRI scanner. A combination of transverse and sagittal images were used to reconstruct the major anatomical features from the buttocks through to the knees, including bone, muscle and fat tissue perimeters, using Solidworks® software. MRI-based reconstruction of the pelvis was enhanced using a template model developed in previous work. A non-rigid registration algorithm was used to fit the pelvis template into the MRI data. Both the left and the right sides of the model were constructed due to the intended asymmetric posture of the volunteer during the MRI measurements. The presented subject-specific model of the buttocks and thighs will add value to optimisation cycles in automotive seat development when used in simulating human interaction with automotive seats.
Keywords: biomechanics, digital human modelling (DHM), image registration, magnetic resonance imaging
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Session 3: Bio-Mechanics I Paper No: 142 Time: 1040 – 1100 Venue: Napier 102 Chair: Dr. Paul Grimshaw Presenter: Reza Shahmiri
Finite element analysis of an implant-assisted removable partial denture with different positions of the rest arm Reza Shamiri1 and Raj Das1* 1 Centre for Advanced Composite Materials, Department of Mechanical Engineering, University of Auckland, New Zealand *Corresponding author. Email: [email protected]
Abstract: When implants are incorporated into an existing removable partial denture, fracture of the acrylic base often occurs. The aim of this study is to analyse the effects of the rest arm position on an implant-assisted removable partial denture using finite element analysis (FEA). A Faro Arm scan was used to extract the geometrical data of a human partially edentulous mandible. A standard plus regular neck (4.8 x 12 mm) Straumann® implant and titanium matrix, tooth roots and periodontal ligaments were modelled using a combination of reverse engineering in Rapidform XOR2 and solid modelling using the Solid Works® CAD program. The model incorporated a removable partial denture (RPD) and was loaded with realistic bilateral forces. The commercial FEA program ANSYS Workbench 14.0 was used to analyse the stress and strain distributions in the implant assisted RPD and in the metal framework. It is found that moving the position of the rest arm from the mesial to distal side of abutment teeth improves the stress distribution in the metal framework and acrylic denture base structures. The metal frame work and acrylic structures were subjected to lower stresses in an implant-assisted removable partial denture (IARPD) with a distal arm design compared to an IARPD with a mesial arm design.
Keywords: dental implant, implant-assisted, removable partial denture, resilient attachment, rest arm.
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Session 3: Bio-Mechanics I Paper No: 162 Time: 1100 – 1120 Venue: Napier 102 Chair: Dr. Paul Grimshaw Presenter: Mohammad Uddin
On the influence of acetabular cup wear and orientation on contact mechanics of dual mobility hip implants Mohammad S. Uddin School of Advanced Manufacturing and Mechanical Engineering, University of South Australia, Adelaide, SA 5095 *Corresponding author. Email: [email protected]
Abstract: Cup wear and orientation on the pelvic bone are significant factors, which change the contact of the articulating surfaces, thus, impacting the long-term performance of the hip implants. This paper presents a finite element (FE) analysis of the contact of the dual mobility implants under the influence of cup wear and inclination. The cup inclination is defined as the angle between the plane passing through the rim of the cup and the horizontal plane. A three-dimensional (3D) FE model of the implant was developed with the application of equivalent physiological loading and boundary conditions. Effects of cup inclination angle ranging from 45 to 60° and the wear ranging from 0 to 2.46 mm equivalent to up to 30 years of the implant’s life on the contact pressure and Von Mises stress were investigated. Individual and combined effects of both important parameters are analysed and discussed with respect to available clinical/laboratory studies.
Keywords: contact pressure, dual mobility hip implants, cup inclination angle, Von Mises stress, wear.
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Session 3: Bio-Mechanics I Paper No: 209 Time: 1120 – 1140 Venue: Napier 102 Chair: Dr. Paul Grimshaw Presenter: Narasimha MurthyThota
Develop and validate a biomechanical surrogate of the human thorax using corrugated sheets: A feasibility study Narasimha MurthyThota*, Jayantha A. Eepaarachchi and K.T. Lau Centre of Excellence in Engineered Fibre Composites, University of Southern Queensland, Toowoomba, Queensland *Corresponding author. Email: [email protected]
Abstract: In this paper, a methodology which was devised to develop and validate a simple, easy to use biomechanical surrogate of the thorax made up of corrugated sheets that can minimize the use of experiments with anesthetized animals, cadavers and expensive Finite Element Models for evaluation of blunt thoracic trauma, is presented. Though the methodology presented in this paper was aimed at developing a surrogate of the thorax which emulates 3-RCS (a widely used high fidelity thorax model developed by Wayne State University), to prove the feasibility of the proposed methodology a pilot study was carried out in which, a target made up of corrugated sheets was correlated with the thorax of the Hybrid III ATD. For the pilot study, a series of computer aided engineering (virtual testing) analyses were carried out with the thorax of the Hybrid III 50th percentile rigid male dummy, which was impacted with a 27.3 gram, 40 mm projectile with foam nose and PVC base, at 50–100 m/s (with an increment of 5 m/s) and force–time responses were measured. By varying the design parameters of the target, numerical simulation iterations were carried out to achieve the correlation with the thorax of Hybrid III dummy.
Keywords: biomechanical surrogate, 3-rib chest structure, blunt trauma, thorax, non-lethal, sports injuries, hybrid-III dummy.
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Session 3: Bio-Mechanics I Paper No: 047 Time: 1140 – 1200 Venue: Napier 102 Chair: Dr. Paul Grimshaw Presenter: Daniel J. Searson
Use of a damped Hertz contact model to represent head impact safety tests Daniel J. Searson*, Robert W. G. Anderson and Timothy P. Hutchinson Centre for Automotive Safety Research, University of Adelaide, Australia *Corresponding author. Email: [email protected]
Abstract: Head impacts tests are conducted as part of many types of safety testing, with applications including vehicle crashes, helmets and sports surfaces. A common measure of head injury in these tests is the Head Injury Criterion (HIC), which is calculated from the measured acceleration of a headform during the impact. In this paper, these headform impacts are represented by a Hertz contact model to which a damping term has been added. A power law relationship was found to be appropriate for modelling the effect of headform mass and impact speed on HIC and peak displacement. It was found that the stiffness and damping in the model did not affect the exponents in the power law, but the exponent of displacement in the contact model did have an effect on all of the exponents in the power law. This result may explain why some variation exists in real data. The relationships presented in this paper may be used to predict how the HIC and maximum displacement of the head will vary for a given change in head mass or impact speed. This has applications in test protocol development and for evaluating the safety performance of tested structures under a variety of real world conditions.
Keywords: Contact mechanics, impact, head injury, headform testing.
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Session 4: Composites I Paper No: 172 Time: 1350 – 1410 Venue: Napier G03 Chair: Prof. Bob Adams Presenter: Chun. H. Wang
Effects of adherend thickness on the bond strength measurement of adhesive bonded repairs Mildred Lee1, Chun H. Wang1*, Eudora Yeo2 and Madabhushi Janardhana3 1 School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Australia. 2 Defence Science and Technology Organisation, Australia 3 Aircraft Structural Integrity - Directorate General Technical Airworthiness, RAAF, Australia *Corresponding author. Email: [email protected]
Abstract: The Pneumatic Adhesion Tensile Testing Instrument (PATTI) has been used to measure the residual strength of bonded patch repairs on retired aircraft in order to assess the durability of the repairs. The PATTI tests performed on the patch repair on a fatigue-cracked aircraft wing showed that the bond strength at the edges of the patch was significantly lower than those in the central region, raising possible doubts of substantial bond degradation during service. To investigate this further, this paper presents an experimental and computational investigation on the influence of adherend thickness, representing the tapered region of the repair patch, on the bond strength obtained using PATTI, which was originally developed for testing coatings on thick substrate. The results reveal that the adherend thickness has a major effect on the PATTI tensile strength.
Keywords: bond durability, environmental conditioning, variable adherend thickness.
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Session 4: Composites I Paper No: 202 Time: 1410 – 1430 Venue: Napier G03 Chair: Prof. Bob Adams Presenter: Muhammad A. Ashraf
Flexure analysis of composite pipes during reeling process Muhammad A. Ashraf1,2*, Evgeny V. Morozov1, Krishnakumar Shankar1 1 School of Engineering and Information Technology, University of New South Wales, Canberra, Australia. 2 Cooperative Research Centre for Advanced Composite Structures, Fishermans Bend, Victoria, Australia. *Corresponding author. Email: [email protected]
Abstract: Composite pipes are considered as an attractive alternative to conventional steel pipes for the transportation of oil and gas products due to their advanced properties such as high strength-to-weight ratio and better corrosion resistance performance. Efficient implementation of composite flow lines is often achieved by employing the reel-lay installation method. In this method, long continuous sections of pipe can be spooled on a reel and then unspooled and deployed at any desired location. Although being a convenient and cost effective way of installation, this method imposes special requirements on the composite pipe to be spoolable in addition to withstanding the operational pressure and thermal loads. Mechanical behaviour of the reeled metallic pipes has been extensively reported in the literature; however, as for their composite counterparts, this area still needs to be explored. In particular, the possible buckling of the reeled composite pipes needs to be investigated in detail in order to fulfil the design requirements. In the current work, the bending of composite pipes during the reeling process of reel-lay installation is modelled using non-linear FEM (ABAQUS). The pipe has been modelled with shell elements and the buckling of the pipe under pure bending has been studied using non-linear large deformation analysis. Also, Maximum-stress and Tsai-Hill failure criteria are utilized to identify the maximum bend limit of the composite pipe based on material strength. The effects of the different diameter-to-thickness ratios of the composite pipe on the bending behaviour have been studied.
Keywords: buckling, composite pipes, finite-element method, reel-lay, stress analysis.
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Session 4: Composites I Paper No: 064 Time: 1430 – 1450 Venue: Napier G03 Chair: Prof. Bob Adams Presenter: Nima A. Zanjani
Investigation on the wrinkling limit diagram of self-reinforced polypropylene woven composite at room temperature Nima A. Zanjani* and Shankar Kalyanasundaram School of Engineering, Australian National University, North Road, Canberra 0200, Australia *Corresponding author. Email: [email protected]
Abstract: Wrinkling is one of the most common instabilities that occur during forming of prepreg and consolidated composite sheets. It is generally undesirable as it decreases the strength of the parts and gives an unacceptable appearance to the final product. In this study occurrence of wrinkling during forming of self-reinforced polypropylene (SRPP) is investigated by application of uniaxial extension test on specially designed samples. These specimens were extended uniaxially by an INSTRON machine until wrinkles appeared on their surface. Principal strains evolution have been recorded by an in-situ 3D photogrammetric measurement system and then plotted in strain space. This determined Wrinkling Limit Diagram (WLD) which could be utilized to distinguish between safe and wrinkled regions during forming of pre-consolidated woven SRPP. In addition, the forming behaviour of pre-consolidated woven sheets of SRPP during uniaxial extension will be elucidated in terms of major and minor strains development.
Keywords: wrinkling, major and minor strain, strain evolution, woven thermoplastic composite materials, wrinkling limit diagram.
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Session 4: Composites I Paper No: 053 Time: 1450 – 1510 Venue: Napier G03 Chair: Prof. Bob Adams Presenter: Shankar Kalyanasundaram
Numerical investigation of the effect of temperature on the formability of a thermoplastic fibre metal laminate Sivakumar DharMalingam1, Anthony Sexton2, Sudharshan Venkatesan2 and Shankar Kalyanasundaram2* 1 Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka, Melaka, Malaysia 2 Research School of Engineering, The Australian National University, Canberra, Australia *Corresponding author. Email: [email protected]
Abstract: Numerical analysis of the stamp forming of FML systems would provide a powerful tool for the optimisation of the process parameters and a fundamental understanding of the deformation behaviour of this material system. This study uses the finite element analysis software, LS-DYNA, to simulate the effect of temperature on the stamp forming of a FML based on a polypropylene based composite. This numerical model is validated through comparison with experiments conducted using a hemispherical punch and non-contact optical measurement system. The combination of real-time optical strain measurement and non-linear FEA to analyse and predict the forming of this material is a significant advancement in the understanding of FML systems. A major conclusion derived from the FE simulations and experiments is that temperature is an important metric to the forming behaviour of the FML.
Keywords: Fiber reinforced composite, dome forming, fibre metal laminate, finite element analysis, temperature effects.
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Session 5: Dynamics II Paper No: 147 Time: 1350 – 1410 Venue: Napier G04 Chair: Prof. Robert Randall Presenter: Kris McKee
Modification of the ISO-10816 centrifugal pump vibration severity charts for use with Octave band spectral measurements Kristoffer K. McKee1*, Gareth L. Forbes2, Ilyas Mazhar2, Rodney D. Entwistle2, Ian Howard2 and Tendekai Mapeza3 1 Department of Mechanical Engineering, Curtin University, Perth Australia and CRC for Infrastructure and
Engineering Asset Management 2 Department of Mechanical Engineering, Curtin University, Perth Australia 3 Gold Coast Water *Corresponding author. Email: [email protected]
Abstract: The ISO standard 10816 gives acceptance levels of vibration for centrifugal pumps in the form of a severity Chart. The measured 10-1000 Hz RMS velocity vibration of pumps within a given size and physical setup can be judged against the severity chart limits to give an indication of the pumps running health. This single RMS velocity value, although having being shown to be a reasonably robust measurement tool for analysing the condition of a centrifugal pump, does not allow discrimination between failure types resulting in the increased vibration, and indeed overlooks the subtleties of the pump condition state. This limitation in the use of general RMS velocity vibration levels for use with rotating machinery health is well documented, and a vast number of more sophisticated techniques, to pin point faults in specific machinery, have been developed. These techniques, although powerful, often require detailed information, such as the number of balls in a specific bearing within the machine. This information is often not readily available for a given pump setup. Tailoring these sophisticated vibration diagnostic tools for a specific pump setup can require a considerable amount of man hours and expertise, therefore having general vibration diagnostic tools which don’t require extensive data about the particular pump setup would be ideal.
It is proposed in this paper that the use of Octave band spectral measurements of pump vibration can strike a better balance between the two extremes of vibration analysis being: (i) overall RMS vibration velocity levels, (ii) highly specific analysis techniques such as envelope analysis for bearing fault detection. The use of Octave band spectral measurements still allows broad employment in centrifugal pump setups without a high degree of specific setup details being required. Within this paper modification of the ISO-10816 severity charts for use with Octave frequency band measurements is presented. With the use of some in-field vibration measurements, initial justification and validation of the modified vibration severity levels is presented.
Keywords: condition monitoring, centrifugal pumps, vibration severity levels, octave band spectrum.
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Session 5: Dynamics II Paper No: 133 Time: 1410 – 1430 Venue: Napier G04 Chair: Prof. Robert Randall Presenter: Iuliia Karachevtseva
Investigation of influence of technological imperfections on the dynamic behavior of the packages of the steam turbine blades Iuliia Karachevtseva1,2*, Valery Zhovdak3**, Elena Pasternak1 and Arcady V. Dyskin2 1 School of Mechanical and Chemical Engineering, The University of Western Australia 2 School of Civil and Resource Engineering, The University of Western Australia 3 National Technical University “Kharkiv Polytechnical Institute”, Kharkiv, Ukraine *Corresponding author: Email: [email protected] **(1946-2009)
Abstract: The paper deals with the problems arising from the operation of steam turbines. We explore the effects of blade mistuning on the dynamic behaviour of the packages of blades. The paper presents the results of numerical analysis of forced vibrations of the packages of the fourth stage of a steam turbine with the technological imperfections. The gap between the blade bandages is caused by the technological imperfections at the stage of assembling. The slope of the gap is in the range of 0 to 0.9º. We considered two types of blade packages: with technological imperfections and identical ideal package without the gaps. The proposed mathematical and finite-element models show the influence of technological imperfections on mechanical behaviour of the steam turbines. The technological mistuning decreases the stiffness of the system and the eigen frequencies and increases the amplitudes of the vibrations. The considered mistuning in the blades assemblies has a significant effect on the dynamic properties and on the contact interactions of the steam turbine blade packages.
Keywords: blade packages, oscillations, steam turbine, stiffness, technological imperfections, blade mistuning.
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Session 5: Dynamics II Paper No: 131 Time: 1430 – 1450 Venue: Napier G04 Chair: Prof. Robert Randall Presenter: Igor Shufrin
Stationary points created by resonances in a chain of bilinear oscillators Igor Shufrin1,2*, Arcady V. Dyskin1 and Elena Pasternak2 1School of Civil and Resource Engineering, The University of Western Australia, Australia 2 School of Mechanical and Chemical Engineering, The University of Western Australia, Australia *Corresponding author. Email: [email protected]
Abstract: This study investigates resonances in the symmetrical systems of coupled bilinear oscillators (identical masses connected by identical bilinear springs). The bilinear oscillators are often used to model the dynamics of various discontinuous systems exhibiting different stiffnesses in compression and tension. These natural and engineering systems are normally characterised by multiple degrees of freedom and their behaviour is far from being completely understood. In this study, we present a method for determination of the resonances in a one-dimensional chain of bilinear oscillators. We demonstrate that the resonant frequencies of the system coincide with the resonant frequencies of two basic oscillators: a one-mass oscillator and a two-mass oscillator. In resonance, the system oscillates as independent basic oscillators, effectively decomposing itself into either one-mass oscillators or two-mass oscillators. These basic oscillators are separated by masses, which remain stationary (stationary points). The presence of these stationary points is a unique feature of the symmetrical systems of bilinear oscillators. We also show that the super-harmonic resonances (resonances at frequencies multiple of the main frequency) and sub-harmonic resonances well known in single bilinear oscillators can occur in the chains of the bilinear oscillators.
Keywords: bilinear oscillator, linear states, resonance, stationary points.
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Session 5: Dynamics II Paper No: 188 Time: 1450 – 1510 Venue: Napier G04 Chair: Prof. Robert Randall Presenter: Zhen Luo
Comparison of interval method and Polynomial Chaos method for solving dynamics problem with uncertainties Jinglai Wu1, Zhen Luo1*, Nong Zhang1*, Yunqing Zhang2 and Liping Chen2
1 School of Mechanical and Mechatronic Engineering, University of Technology, Sydney, NSW 2007 2 School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan,
Hubei 430074, China *Corresponding author. Email: [email protected]
Abstract: The parameters in most engineering problems are under uncertainty due to manufacturing and assembly tolerances, deviations in loads and other environmental factors, which make the uncertainty of system response too notable to be ignored. Two methods are used to solve uncertain problems in this paper, in which the polynomial chaos method is tailored for random variables while the interval method is used to fit for interval variables. The polynomial chaos method, belonging to a kind of probabilistic methods, can be used to obtain statistic characteristics of the response but requires the statistic information of uncertain parameters. The interval method to be proposed is based on the Runge-Kutta algorithm to solve ordinary differential equations (ODEs) with interval parameters. Taylor inclusion model is included in the numerical implementation, and the Taylor coefficients are calculated through real point iterative process, which is expected to reduce the overestimation intrinsic to interval computations. The vehicle handling problem is used as an engineering application to demonstrate the effectiveness of the proposed method. In the numerical model, the uncertain parameters are modelled as interval parameters and random parameters, respectively. The results show that: (1) the polynomial chaos method makes the mean value of responses consistent with the Monte Carlo simulation, but the standard deviation of responses exhibits large error; (2) the interval method achieves the bounds of responses which contain the actual results tightly; (3) both the polynomial chaos and interval methods are more computationally effective than the Monte Carlo simulation.
Keywords: uncertainty; dynamic systems; interval methods; Polynomial chaos method; Runge-Kutta method.
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Session 6: Bio-Mechanics II Paper No: 046 Time: 1350 – 1410 Venue: Napier 102 Chair: Prof Wing Kong Chiu Presenter: Zhongxiao Peng
Investigation of nano-mechanical properties of cartilages of sheep knee joints Zhongxiao Peng1*, Meiling Wang1 and Ling Yin2 1 School of Mechanical & Manufacturing Engineering, The University of New South Wales Sydney, NSW 2052 2 School of Engineering & Physical Sciences, James Cook University, Townsville, Qld 4811 *Corresponding author. Email: [email protected]
Abstract: Articular cartilage is a special load-bearing material which protects joint surfaces with a remarkably low friction coefficient. Its mechanical properties have attracted interests both at research and clinical application level. This paper presents a study of nano-mechanical properties of cartilages. To better understand degradation processes of articular cartilage, an animal model was established to generate cartilage samples in different wear conditions. Using this controlled wear testing method cartilage samples in osteoarthritis (OA) grades 0-3 were obtained. The samples were nano-indented so their hardness and Young’s modulus were studied to gain a better understanding of the nano-mechanical properties of this complex, inhomogeneous material.
Keywords: articular cartilage; bio-mechanical properties; nano-indentation; osteoarthritis.
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Session 6: Bio-Mechanics II Paper No: 073 Time: 1410 – 1430 Venue: Napier 102 Chair: Prof Wing Kong Chiu Presenter: Lloyd Fletcher
Effects of irradiation and non-enzymatic glycation on the fracture resistance of bovine cortical bone Lloyd Fletcher1*, John Codrington1,2 and Ian Parkinson2,3 1 School of Mechanical Engineering, The University of Adelaide, Adelaide, SA, Australia 2 Bone and Joint Research Laboratory, SA Pathology and Hanson Institute, Adelaide, SA, Australia 3 Discipline of Anatomy and Pathology, The University of Adelaide, Adelaide, SA, Australia *Corresponding author. Email: [email protected]
Abstract: Bone is a complex multi-phase composite having mechanical properties that are strongly dependent on its constituent parts. Components contributing towards the overall mechanical quality of bone include the organic phase (primarily Collagen I) and the inorganic phase (Hydroxyapatite). However, the individual contribution of each of the material phases towards crack propagation and the inherent fracture toughening mechanisms that are observed in bone are not well understood. Therefore, this study aims to investigate the contribution of the organic and inorganic constituents to the fracture resistance of cortical bone. Three treatment methods were selected that independently alter either the organic or inorganic components of cortical bone. The first two treatments effect the organic phase by denaturation of the collagen and formation of natural enzymatic cross-links from exposure to irradiation, and by incubation in a Ribose solution to induce Non-Enzymatic Glycation (NEG). The third treatment alters the inorganic phase by decalcification in ethyl-diamine-tetra-acetic acid (EDTA). Following treatment, the specimens were mechanically tested to obtain the fracture resistance curve as a function of crack growth using the unloading compliance method. To supplement this technique, stages of the crack growth were sequentially labelled using fluorochrome stains to observe the crack path as well as the toughening mechanisms (e.g. ligament bridging). Overall, the results of this study show that the organic phase is responsible for the toughening and fracture resistance behaviour of cortical bone while the inorganic phase contributes to its stiffness. The results of this study also suggest that the formation of natural enzymatic cross-links and protein denaturation due to irradiation are more detrimental to the fracture resistance of cortical bone than the non-enzymatic cross-links formed by NEG.
Keywords: bone fracture, cortical bone, fracture resistance, irradiation, non-enzymatic glycation.
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Session 6: Bio-Mechanics II Paper No: 051 Time: 1430 – 1450 Venue: Napier 102 Chair: Prof Wing Kong Chiu Presenter: Stefano C. Meliga
Determination of stress field caused by microprojection arrays contacting and impacting hyperelastic layered skin Stefano C. Meliga1, Christopher Flaim1, Martin Veidt2, and Mark A.F. Kendall1,3* 1 Delivery of Drugs and Genes Group (D2G2), Australian Institute for Bioengineering and Nanotechnology, The
University of Queensland, Brisbane, QLD 4072, Australia 2 School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia 3 The University of Queensland, Diamantina Institute, Brisbane, QLD 4102, Australia *Corresponding author. Email: [email protected]
Abstract: The Nanopatch™ is a silicon array of microprojections for epidermal and dermal delivery of vaccines, resulting in enhanced immunogenicity in comparison to intramuscular injection. Achieving this requires the fracture of skin superficial barriers and penetration to the targeted depth, reliant upon negotiating the complex non-linear elastic and failure properties of skin — a multilayer composite ‘biomaterial’. In this work, computational models of projection-skin mechanical interaction are developed and applied to investigate the mechanical stress generated to fracture skin. Our analytical results on a homogenous linear-elastic skin model suggest that the array projections exert an uneven force distribution on the skin surface, leading to a non-homogeneous stress across the loaded skin region. In addition, the creation of high localized tensile stress is sensitive to a precise trade-off between projection spacing and tip diameter. Numerical simulations are further performed using a layered hyperelastic skin representation and compared with the analytical findings. The resulting deformation and stresses are significantly increased due to, respectively, the compliant top skin layers and their non-linear elastic properties. This underlines the importance of accounting for the stratified structure of the skin as well as the strain-hardening properties of its strata when assessing the achievement of failure criteria.
Keywords: epidermal and dermal vaccine delivery, hyperelastic layered material, microprojection array, NanopatchTM, skin penetration.
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Session 6: Bio-Mechanics II Paper No: 199 Time: 1450 – 1510 Venue: Napier 102 Chair: Prof Wing Kong Chiu Presenter: Xiaofei Wang
Parametric studies of optic chiasmal compression biomechanics using finite element modelling Xiaofei Wang1*, Andrew Neely1, Christian Lueck2,3, Murat Tahtalı1, Gawn McIlwaine4,5 and Thomas Lillicrap2,3 1 School of Engineering and Information Technology, University of New South Wales Canberra, Canberra, ACT,
Australia 2 The Canberra Hospital, Canberra, ACT, Australia 3 Australian National University, Canberra, ACT, Australia 4 Queen’s University Belfast, Belfast, Northern Ireland, UK 5 Belfast Health and Social Care Trust, Belfast, Northern Ireland, UK *Corresponding author. Email: [email protected]
Abstract: A tumour of the pituitary gland can compresses the chiasm from below and can cause bitemporal hemianopia. This is a type of partial blindness caused by damage to the crossed nerve fibres which carry the information from the temporal visual field. So far, the reason why chiasmal compression selectively damages the crossed nerve fibres is still unclear. In vivo experiments have been performed to investigate the mechanical behaviours of the optic chiasm, but none of them has provided detailed stress/strain distributions due to the complexity of the experiment. In this paper, three-dimensional finite element models were built in ANSYS to investigate the stress distribution in the optic chiasm when the chiasm was elevated by a pituitary tumour that grows beneath it. Optic nerve fibre models were also established to investigate the difference in resulting stress distributions in the crossed and uncrossed fibres. Parametric studies were conducted to measure the dependence of the resulting stress fields on alterations in the optic nerve sheath thickness, elastic modulus of the pial sheath and nerve tissue, and angles between nerve fibres. The study showed that changes of all these parameters above can affect the stress value in the chiasm significantly. Although marked absolute differences were found in these models, the stress distributions showed similar trends in all conditions. It was found that the central aspect of the chiasm always bore higher stresses than the peripheral aspect of the chiasm. In the nerve fibre models, for a given load the average stress increased with increasing crossing angle between nerve fibres.
Keywords: bitemporal hemianopia, chiasmal compression, finite element modelling, pituitary tumour.
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Session 7: SHM & NDT I Paper No: 125 Time: 1540 – 1600 Venue: Napier G03 Chair: A/Prof Martin Veidt Presenter: Jiawen Su
Investigating mode coupling effects in composites beams with delamination damage Jiawen Su1, Chin K. Liew1, Martin Veidt1* 1 School of Mechanical & Mining Engineering, The University of Queensland, Brisbane, Australia *Corresponding author. Email: [email protected]
Abstract: This project investigates mode coupling effects in laminated composite beams with delamination damage. 8-ply composite beams from carbon fibre woven fabric and different configurations of artificial delamination damage are used in the study. A 3-D explicit finite element simulation modelling the woven layers as transversely isotropic materials are developed to analyse the propagation and scattering behaviour of the fundamental anti-symmetric Lamb wave mode (A0). The results from the 3-D numerical model were in good agreement with analytical solutions derived from the Timoshenko beam theory in terms of phase velocities of the A0 mode. Reflection and transmission coefficient spectrums of two delamination sizes were generated based on the 3-D numerical model. The reflection and transmission spectrums were found to be dependent on the location of measurement points being selected due to the fact that the amplitude of incident wave varies periodically along the length of the beam as well as the width. The wave amplitudes across the width of the beam should also be considered in order to obtain more stable reflection and transmission coefficient spectrums.
Keywords: delamination damage, fibre-reinforced composites, Lamb waves, mode conversion, non-destructive testing.
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Session 7: SHM & NDT I Paper No: 068 Time: 1600 – 1620 Venue: Napier G03 Chair: A/Prof Martin Veidt Presenter: Jiahua Yang
Model updating based structural damage detection of transmission tower: experimental verification by a scaled-model Jiahua Yang1* and Heung-Fai Lam1 1 Department of Civil and Architectural Engineering, City University of Hong Kong, Hong Kong, China *Corresponding author. Email: [email protected]
Abstract: Transmission towers play a significant role in the distribution of electrical power. With the recent collapse of transmission tower at Sichuan, China on December 14, 2011, Structural Health Monitoring (SHM) of transmission towers becomes a hot research topic. According to the literature, it is impractical and impossible to develop a “general” method that can detect all kinds of damages for all types of structures. A practical method should take the characteristics of the type of structures and the kind of damages into consideration. For transmission towers, the buckling of secondary members (braces) due to strong wind during typhoon is not uncommon. The vibration of the tower caused by external excitations due to wind and workers during maintenance contains information about the structure’s stiffness and mass distribution. Therefore, it is possible to detect damages on the tower based on the measured vibration responses of the structure. This paper reports a feasibility study on the use of vibration data of transmission towers in the detection of damaged braces by following a model-based approach. A three-dimension finite element model (FEM) program was developed in MATLAB® for the computer modelling of the target transmission tower in this paper. A newly developed substructure-based structural model-updating scheme is employed to identify the stiffness distributions of the target transmission tower under the undamaged and damaged conditions based on the corresponding sets of measured modal parameters. By comparing the identified stiffness distribution, the damage locations and the corresponding extents can then be estimated. The contributions of this paper are not only on the development of the substructure-based model updating scheme but also on the verification of the proposed methodology through measured data from a scaled transmission tower model under laboratory conditions.
Keywords: damage detection, transmission tower, modal identification, model updating.
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Session 7: SHM & NDT I Paper No: 146 Time: 1620 – 1640 Venue: Napier G03 Chair: A/Prof Martin Veidt Presenter: Dr. Ching-Tai Ng
The low-frequency scattering of the A0 Lamb wave from delaminations in quasi-isotropic composite laminates: Theoretical and finite element studies Ching-Tai Ng1*, Martin Veidt2, L. R. Francis Rose3 and Chun H. Wang4
1 School of Civil, Environmental & Mining Engineering, The University of Adelaide, Adelaide, SA 5005, Australia 2 School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia 3 Air Vehicles Division, Defence Science and Technology Organisation, Melbourne, VIC 3207, Bundoora, VIC
3083, Australia 4 Sir Lawrence Wackett Aerospace Centre, School of Aerospace, Mechanical and Manufacturing Engineering,
RMIT University, Melbourne, VIC 3001, Australia *Corresponding author. Email: [email protected]
Abstract: This paper presents a scattering analysis of the fundamental anti-symmetric (A0) Lamb wave at delaminations in quasi-isotropic (QI) composite laminates. The scattering characteristics are investigated using theoretical solutions and experimental verified three-dimensional (3D) finite element (FE) simulations. Analytical models based on the Mindlin plate theory and Born approximation are used to predict the A0 Lamb wave scattering at delaminations and the results are then compared with FE predictions. The delaminations are modelled as an inhomogeneity in an equivalent isotropic model of the QI composite laminates and as a volume split in the layered composite laminates for theoretical solutions and FE simulations, respectively. The results show that there is a good correlation between the theoretical solutions and FE results in the forward scattering amplitudes but there exists a larger discrepancy in the backward scattering amplitudes. In addition the FE predictions show that the fibre direction of the outer laminae has a pronounced influence on the forward and backward scattering amplitudes, which is not predicted by the theoretical solutions. This paper studies the feasibility of the common theoretical approach of modelling the delaminations as inhomogeneities which indicates the possibility of extending the Lamb wave diffraction tomography from isotropic plates to QI composite laminates.
Keywords: composite laminate, delamination, diffraction tomography, Lamb wave, scattering.
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Session 7: SHM & NDT I Paper No: 176 Time: 1640 – 1700 Venue: Napier G03 Chair: A/Prof Martin Veidt Presenter: Wingkong Chiu
Numerical investigation of the scattering of ultrasonic guided wave in hard-to-inspect regions Cain Doherty1 and Wing K. Chiu1*
1 Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3800,
Australia *Corresponding author. Email: [email protected]
Abstract: Fuel weep holes in aircraft wing risers are common fatigue critical locations for crack initiation. Whilst cracks that grow from the surface of the weep holes toward the wing skin can be easily inspected outside the aircraft by traditional ultrasonic and current state-of-the-art stress wave based SHM methodologies, cracks that grow away from the wing-skin on the blind side of the hole pose a much greater challenge. This paper shall present a set of computational investigation to emphasis the merit in the development of 3D finite element models for the analysis of complicated hard-to-inspect geometries in health monitoring applications. The development of reliable and effective health monitoring methodologies for hard-to-inspect structures is dependent on such knowledge of elastic wave scattering from defects. Future work will be focussed on identifying the contributions that individual wave modes make to the scattered wave field such that the physics can be fully exploited for hard-to-inspect sub-surface damage.
Keywords: circumferential creeping wave, fatigue crack, finite element, in-situ structural health monitoring, lamb wave, non-destructive, modelling, piezoceramic, weep hole.
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Session 8: Manufacturing Paper No: 065 Time: 1540 – 1600 Venue: Napier G04 Chair: Dr. Daniel Yuen Presenter: Nima A. Zanjani
Effect of aspect ratio variations on forming limit diagram of glass-fibre reinforced polypropylene composite at room temperature Nima A. Zanjani1*, Shankar Kalyanasundaram1 1 Research School of Engineering, Australian National University, North Road, Canberra, Australia *Corresponding author. Email: [email protected]
Abstract: This study investigates the formability of pre-consolidated glass-fibre reinforced polypropylene composite during stretch forming conditions. Fixed boundary condition was applied to the sheets through a lock-ring and samples were deformed up to the depth of failure in an open-die custom-built press by a hemispherical punch. Specimens with different aspect ratios were employed to induce different deformation modes. Deformations and their evolutions were captured and recorded by an in-situ 3D photogrammetric measurement system (ARAMIS). Resultant major and minor strains were calculated and plotted in 2D strain space to construct a Forming Limit Diagram (FLD) which elucidates safe and failed deformation margins during stamp forming procedure. It was found out that Woven glass-fibre reinforced all-polypropylene composite sheets do not tend to exhibit thinning or localized necking behaviour during forming and hence their Forming Limit Diagrams would not contain marginal regions as in sheet metals.
Keywords: deformation modes, forming limit diagram, major and minor strain, strain evolution, woven thermoplastic composite materials.
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Session 8: Manufacturing Paper No: 132 Time: 1600 – 1620 Venue: Napier G04 Chair: Dr. Daniel Yuen Presenter: Nixon Kuruvila
Parametric influence and optimization of wire-EDM on hot die steel Nixon Kuruvila1*, H.V. Ravindra2, Joe Elambasseril3 1 Dept.of Mechanical Engineering, Sahrdaya College of Engg & Tech, Thrissur, Kerala, India -680684 2 Dept.of Mechanical Engineering, PES College of Engineering, Mandya, Karnataka, India -571401 3 Department of Mechanical & Manufacturing Engineering, RMIT University, Bundoora, VIC, Australia *Corresponding Author email:[email protected]
Abstract: Wire-cut Electro Discharge Machining (WEDM) is a special form of conventional EDM process in which electrode is a continuously moving conductive wire. The present study aims at determining parametric influence and optimum process parameters of Wire-EDM using Taguchi’s technique and Genetic algorithm. The variation of the performance parameters with machining parameters was mathematically modeled by Regression analysis method. The objective functions are defined as Dimensional Error (DE), Surface Roughness (SR) and Volumetric Material Removal Rate (VMRR). Experiments were designed as per Taguchi’s L16 Orthogonal Array (OA) where in Pulse-on duration, Current, Pulse-off duration, Bed-speed and Flushing rate have been considered as the important input parameters. The matrix experiments were conducted for the material Hot Die Steel (HDS) having the thickness of 40 mm. The Heat Affected Zone (HAZ) characteristics of the eroded materials were assessed by Scanning Electron Microscope (SEM) and the microhardness of the material was tested using Vickers microhardness tester. The results of the study reveal that among the machining parameters, it is preferable to go in for smaller pulse-off duration for achieving over all good performance. Regarding pulse-on duration, higher values are recommended for error constrained machining with higher MRR and constrained/limited values for attaining good surface texture. Smaller current is suggested for better surface finish/texture control, medium range for error control and high value for MRR. Finally, the validation exercise performed with the optimum levels of the process parameters. The results confirm the efficiency of the approach employed for optimization of process parameters in this study.
Key words: Genetic Algorithm, Regression, Taguchi Analysis, Wire Cut Electro Discharge Machining (WEDM).
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Session 8: Manufacturing Paper No: 211 Time: 1620 – 1640 Venue: Napier G04 Chair: Dr. Daniel Yuen Presenter: Keiko Natori
Forming of housing by impact extrusion press using ultrafine-grained semi-solid light metal Keiko Natori1*, Tomoaki Yashima1, Yoshihiko Arao2 and Tatsuya Tanaka2 1 Graduate School of Engineering, Doshisha University, Japan 2 Faculty of Science and Engineering, Doshisha University, Japan *Corresponding author. Email: [email protected]
Abstract: The forming of thin-walled aluminium housing by impact backward extrusion process was conducted, and the influence of metal microstructure on its formability was investigated. Aluminium alloys of A3003, AC4CH-F and semi-solid state of AC4CH were used as test materials. Additionally, ultrafine-grained metal were fabricated by Equal-Channel Angular Pressing method using a die having channel, φ=90°, ψ=15°, from semi-solid AC4CH alloy. And then, cylindrical housings with 9.4mm in diameter and 0.5mm in thickness were formed from as-cast materials and ECAPed samples by impact backward extrusion at room temperature. As a result, press load required for extrusion was decreased using a material processed with increasing the number of ECAP. Vickers hardness of the products was greater than that of the materials before the forming; in the case of using ECAPed materials, the increment was relatively small. This implies that impact extrusion process is a kind of Severe Plastic Deformation that improves mechanical properties of metal materials. Ultrafine-grained semi-solid AC4CH alloy have more possibility to make the housings with further thin thickness than non-ECAP materials.
Keywords: impact extrusion, semi-solid cast, Equal-Channel Angular Pressing, Severe Plastic Deformation, ultrafine grained materials, aluminium alloy.
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Session 8: Manufacturing Paper No: 255 Time: 1640 – 1700 Venue: Napier G04 Chair: Dr. Daniel Yuen Presenter: Shah M. M. Rahman
Development of a trajectory-based 3D surface roughness model for the micro end-milling process Shah M. M. Rahman1* and Jong-Leng Liow1 1 School of Engineering and Information Technology, UNSW_Canberra @ADFA, Australia *Corresponding author. Email: [email protected]
Abstract: Micro end-milling is an important and widely used machining process in the manufacturing industry to make micro products. The surface roughness provides an index of product quality and in most cases is given as a technical specification for the mechanical products. In this study, a three-dimensional (3D) surface roughness model was developed for predicting the structure of the surface generated by the bottom end cutting edges of a micro end-mill. The model simulates the true tool trajectory using the exact geometry of the cutting tool to predict the surface texture and roughness. The accuracy of the model was verified with cutting experiments on Al 6061 and oxygen free high thermal conductivity (OFHC) Copper. Good agreement was obtained between the simulations and experimental results. The proposed model provides a tool for the determination of optimal cutting conditions for micro end-milling.
Keywords: micro end-milling, cutting edge radius, surface roughness.
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Session 9: Life Assessment Paper No: 226 Time: 1540 – 1600 Venue: Napier 102 Chair: Prof. Elena Pasternak Presenter: Pavlo Selyshchev
Non-linear peculiarities of creep in irradiated materials Pavlo Selyshchev1 and Volodymyr Sugakov2* 1 Department of Physics, University of Pretoria, South Africa 2 Department of Theoretical Physics, Institute for Nuclear Research, Ukraine *Corresponding author. Email: [email protected]
Abstract: In the framework of a dislocation climb-glide model a theoretical approach is developed to explain the appearance of a break (local minimum and maximum) on a curve of creep rate dependence on temperature in irradiated materials. The peculiarities of creep temperature dependence were explained by competition of radiation and thermal defect fluxes. At some temperature the both radiation and thermal fluxes become equal and compensate each other, which cause the creep to decrease. It was shown that the presence of sinks with different preference coefficients is important for explanation of appearance of the break. Theoretical and experimental results are in good agreement.
Keywords: climb and-glide of dislocation, creep rate, crystal, defect fluxes, irradiation
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Session 9: Life Assessment Paper No: 246 Time: 1600 – 1620 Venue: Napier 102 Chair: Prof. Elena Pasternak Presenter: Mridul Ashish Pramanik
Life assessment of welded joints operating within creep range Mridul A. Pramanik1 and Sangarapillai Kanapathipillai1* 1 School of Mechanical & Manufacturing Engineering, University of New South Wales, Australia *Corresponding author. Email: [email protected]
Abstract: A significant portion of the high temperature critical components, used in the industrial plants such as power, petroleum, and chemical plants of the world have been in operation for long time like 30 to 40 years, are welded. The heat affected zone causes structural differences compared to unaffected parent metal. Therefore, it is very important to determine possible degradation processes occurring in the weld joint inducing the property changes during long term service and study the behaviour of each zone of the weld joint in the service conditions, as if critical welded components can be replaced before their failure during long term operation. In this paper, a new model has been introduced and implemented to predict the remaining life of weld joints subjected to creep failure at high temperature and compared with other existing models. Initially, finite element analyses of the experimental cases have been done and then numerical results have been used for further calculation according to the proposed model theory to calculate the creep life. A new creep parameter has been found during the implementation of the proposed model which is the function of temperature and material properties. This parameter plays a significant role to control the margin of error of the proposed model. The whole study shows that proposed model provides better degree of accuracy with the experimental cases than the other existing creep life prediction models.
Keywords: creep, finite element analysis, high temperature, life prediction, strain energy density, strain, stress, welded joints.
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Session 9: Life Assessment Paper No: 076 Time: 1620 – 1640 Venue: Napier 102 Chair: Prof. Elena Pasternak Presenter: Anthony Parker
Improving structural integrity assessment of nonlinear packaging materials Matthew J. Lamb1* and Anthony J. Parker2
1, 2 School of Engineering and Science, Victoria University, Australia *Corresponding author. Email: [email protected]
Abstract: During the distribution phase, packaged consignments are exposed to a variety of environmental hazards (such as vibrations) which, if excessively severe, may cause damage to or even destroy the product. Structural deterioration can be tracked by monitoring variations in the packaging system’s modal parameters, particularly its natural frequency (stiffness). Natural frequency estimates are often extracted using a least squares regression curve fit, applied to an estimate of the system’s frequency response function (FRF). FRF estimates are generally obtained using the Fourier transform with a single input and single output (SISO). This approach is suitable for many applications; however, as the nonlinearity of the system under analysis increases, the ability of this technique to accurately monitor changes in the system will decrease.
This paper discusses an approach which is designed to separate the linear component of the system’s FRF using a reverse multiple input/single output (RMISO) algorithm. Such separation will allow traditional modal parameter extraction techniques to be used to monitor the condition of nonlinear systems.
The paper presents the results of preliminary experiments in which expanded polystyrene samples were subjected to broad-band random base excitation with a free-moving load placed atop the cushion sample. Continuous acceleration measurements of the vibration table and the free moving load are used to compute the FRFs of the cushions and the differences between a conventional (SISO) approach and the RMISO based parameter extraction technique are discussed.
Keywords: frequency response function, modal parameter extraction, nonlinear, packaging.
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Session 9: Life Assessment Paper No: 166 Time: 1640 – 1700 Venue: Napier 102 Chair: Prof. Elena Pasternak Presenter: Daren Peng
A simple tool for simulating the growth of rail squats Daren Peng* and Rhys Jones
Department of Mechanical and Aerospace Engineering, Monash University, Victoria *Corresponding author. Email: [email protected]
Abstract: This paper describes the results of the development of squats under alternating loads. An evolutionary program has been developed to simulate squats growth. The code is based on genetic algorithms and the whole field of evolutionary computation. Evolution strategies are derived from the biological process of evolution, to find squats growth path solution to a complex rail/wheel contact problem.
Keywords: computational mechanics, fatigue, squats.
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Session 10: Nano & Micro Mechanics Paper No: 152 Time: 1020 – 1040 Venue: Napier G03 Chair: Prof. Tony Kinloch Presenter: Sergey Lurie
Gradient model of adhesion: mechanical properties and fracture of micro/nano-structured materials Sergey Lurie1,2, Natalia Tuchkova2 , and Juri Soliaev1 1 Department of Nonclassical Models of Composites, Inst. of Appl. Mech. of RAS, Russia, Moscow 2 Department Methods of Differential Equations, Dorodnicyn Comp. Centre of RAS Russia, Moscow *Corresponding author. Email: [email protected]
Abstract: We considered the variational formalism of constructing multiscale models in which the continuum model of adhesion properties directly related to the specific model of the object being modelled. The ideal adhesion properties of interfacial and adhesion properties of defectiveness surfaces is introduced and studied using the gradient adhesion theory. We show that the offered complex gradient adhesion model describes all known superficial effects – a superficial tension, a capillarity, wettability and meniscus. Variational formulation of contact problems for multiphase materials is also considered for modelling of the interfaces in multicomponent materials. As a result we defined the properties of the interfaces in terms of surface properties of the contacting phases. We show that within the framework of the given theory the part of superficial energy is directly connected with defects in the volume and can be used for the modelling the impact of technological factors on the properties of nanostructures. In addition, the proposed model describes the effects associated with the actual damages of the interfaces, such as the surface defects of porous types. We assume that the surface energy which describes the damage of the interfaces defines the appearance of the new surfaces under fracture and can be used for the formulation of the Griffiths- type fracture criterion. We considered some examples in which the properties interfaces can play a sufficient role in the realization of the properties of a micro/nanocomposites.
Keywords: multiscale model, interfaces, interphase layer, fracture, composite materials.
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Session 10: Nano & Micro Mechanics Paper No: 031 Time: 1040 – 1100 Venue: Napier G03 Chair: Prof. Tony Kinloch Presenter: Mei Liu
Origin of the implantation and annealing effects on the residual stress release in a silicon-on-sapphire system Mei Liu, Haihui Ruan and Liangchi Zhang* School of Mechanical and Manufacturing Engineering, The University of New South Wales, NSW 2052, Australia *Corresponding author. Email: [email protected]
Abstract: In semiconductor industry, a thin hetero-epitaxial film layer is normally deposited onto a dissimilar substrate, which inevitably leads to residual stresses and microstructural defects. Ion implantation and subsequent annealing have been used to mitigate such stresses and defects, but the microstructural origin is unclear. This paper carries out an in-depth investigation into the effects of these processes on the stress and microstructure variations in silicon-on-sapphire (SOS) thin film systems undergone Si+ implantation and 600 ºC to 1,000 ºC annealing. The residual stresses were measured by Raman Scattering, whereas the microstructures of the samples were examined by cross-sectional TEM. It was found that the release of the as-grown residual stress after high-energy implantation was more remarkable, and that the increase of ion density leads to more significant stress relief. Under an extreme condition, however, a large number of ions will result in a significant expansion of substrate, causing tension in the silicon film. A higher annealing temperature renders a greater residual stress recovery, an improved crystalline quality, and a clear-cut interface with periodical misfit dislocations. The study concluded that the sapphire lattice expansion caused by ion penetration can hardly be altered by annealing, and as such, the residual stress in the silicon film can be effectively reduced after annealing and an ideal crystal quality can be obtained at the same time.
Keywords: annealing, implantation, stress release, silicon-on-sapphire.
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Session 10: Nano & Micro Mechanics Paper No: 033 Time: 1100 – 1120 Venue: Napier G03 Chair: Prof. Tony Kinloch Presenter: Mohammad Khan
A note on the reliability of nanoindentation: effect of sample standing Fengzai Tang, Haihui Ruan and Liangchi Zhang* School of Mechanical and Manufacturing Engineering, TheUniversity of New South Wales, NSW 2052, Australia *Corresponding author Email: [email protected]
Abstract: This paper discusses the experimental reliability in carrying out nanoindentationson a generally-purposed nanoindentation facility using a stage with magnet buttons for sample holding. The instability of the testing results was found to happen during the nanoindentation on both silicon and quartz samples bonded on different types of stands. It was detected that the maximum indentation depth under the same load function could deviate considerably when such a sample was positioned beyond a certain distance from the centre of a magnet button. It was identified that the application of a thin sample stand led to large deviations, and that using a thick stand would provide more reliable measurements. The most reliable outcome was found to be associated with the testing on the sample directly waxed to the indentation stage without using a sample stand. A systematic analysis revealed that such instability of nanoindentation was caused by the improper contact between a sample stand and the indentation stage, including the insufficient bending rigidity of the stand. It was concluded that a simple solution tothis technical problem is to use a thick enough stand of high bending rigidity and to guarantee a stable contact with the stage surface to obtain sufficient mechanical support to the nanoindentation. This study alerts to the fact that even though the force and deformation in a nanoindentation test are small, the effect of the mechanical support to a sample on the reliability of the testing result can be significant.
Keywords: nanoindentation; mechanical support; quartz; sample stand; silicon; testing reliability.
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Session 10: Nano & Micro Mechanics Paper No: 035 Time: 1120 – 1140 Venue: Napier G03 Chair: Prof. Tony Kinloch Presenter: Mei Liu
The mechanism of nano-scale shear banding in metallic glass Weidong Liu, Haihui Ruan and Liangchi Zhang* School of Mechanical and Manufacturing Engineering, University of New South Wales, NSW 2052 Australia *Corresponding author: [email protected]
Abstract: Shear banding features the deformation of metallic glass (MG) at low temperature. Understanding how a shear band forms is of primary importance for the toughening of MG and for the widening of their applications. This study used the molecular dynamics method to reveal the shear banding mechanisms in MG under different loading conditions. The MG used for the analysis was the binary glass Zr50Cu50. It was found that the underlying mechanism of plastic deformation, which is reflected by the rearrangement of atoms, is characterised by the sudden increase of kinetic energy of local atomic clusters, and that shear banding is a stress-driven coalescence of these localized atomic rearrangements. Under the simple shear loading, a shear band forms at the region of the maximum shear stress. However, under a uniaxial compression, a shear band may not form since there is no particular band of maximum shear stress and the randomly occurred local rearrangements do not necessarily align with the maximum shear direction. As such, the formation of a shear band depends on whether the mismatch strain caused by a local rearrangement is large enough to cause an event in the neighbourhood. The ratio of the local strain rate to the applied strain rate can be used as a severity measure of the local atomic rearrangement. Reducing the applied strain rate can eventually facilitate the shear banding.
Keywords: metallic glass, molecular dynamics, plasticity, shear band, strain rate.
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Session 10: Nano & Micro Mechanics Paper No: 150 Time: 1140 – 1200 Venue: Napier G03 Chair: Prof. Tony Kinloch Presenter: Jesús Toribio
Strength anisotropy and mixed mode fracture in cold drawn prestressing steel wires Jesús Toribio1*, Beatriz González1 and Juan-Carlos Matos2
1 Department of Materials Engineering, University of Salamanca, E.P.S. Zamora (Spain) 2 Department of Computing Engineering, University of Salamanca, E.P.S. Zamora (Spain) *Corresponding author. Email: [email protected] Abstract: Cold drawn prestressing steel wires (used in prestressed concrete) exhibit strength anisotropy in the form of fracture path deflection towards a direction approaching the wire axis, or cold drawing line, as a consequence of the pearlitic microstructure orientation induced by the manufacturing procedure (in the form of a progressive orientation and slenderising of the pearlitic colonies in the drawing direction, together with an also progressive orientation of the ferrite/cementite lamellae in the same direction). Such a crack path deflection is initiated at certain nuclei (fracture origins) at which axial cracking appears in the cold drawing direction (or wire axis) in the form of micro-cleavage units (enlarged cleavage, oriented in such a direction) producing a macroscopic phenomenon of pop-in, a sudden and small decrease of load in the load-displacement curve, caused by the slight loss of bearing capacity of the sample. This paper shows that the described initiators of fracture appear at a certain distance from the fatigue precrack tip at which a local maximum of the cleavage stress is located.
Keywords: cold drawn steel, cleavage stress, fracture path deflection, anisotropy.
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Session 11: SHM & NDT II Paper No: 071 Time: 1020 – 1040 Venue: Napier G04 Chair: Dr. Francis Rose Presenter: Qin Hu
Model updating of the rail-sleeper-ballast system and its application in ballast damage detection Qin Hu1* and Heung F. Lam1 1 Department of Civil and Architectural Engineering, City University of Hong Kong, HKSAR, China *Corresponding author: Tel: +852 27844324. Email: [email protected]
Abstract: There are many methods and instruments developed for the damage detection of the rails of railway track systems. However, the detection of damage on ballast is still relying on visual inspection. It should be pointed out that visual inspection is only effective to observe ballast damage on the surface, but it is impossible to detect the ballast damage under sleepers in this way. The main function of the ballast is to support the sleeper and keep it in position. When the ballast is damaged, the stiffness that can be provided in supporting the sleeper will be reduced. As a result, the dynamic characteristics of the rail-sleeper-ballast system will be altered. Therefore, it is possible to detect the damage of ballast under the sleeper based on the measured vibration responses of the in-situ sleeper.
In order to study the feasibility of this approach, a full-scale ballasted track was built and tested under laboratory conditions. This paper focuses on the model updating of the undamaged rail-sleeper-ballast system utilizing the measured vibration of in-situ concrete sleeper through impact hammer test. Some numerical case studies were carried out by adding noise to the calculated time-domain data to simulate the measured undamaged and damaged time responses. The case study results are very positive showing that the vibration data of the in-situ sleeper does contain information about the ballast status, and model updating is a feasible technique in extracting this information from the noisy data.
Keywords: damage detection, model updating, railway ballast, vibration measurement.
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Session 11: SHM & NDT II Paper No: 048 Time: 1040 – 1100 Venue: Napier G04 Chair: Dr. Francis Rose Presenter: Shuai He
Location and depth of delamination damage determined by an inverse method Shuai He1,2, L. R. Francis Rose1 and Chun H. Wang1* 1 School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, GPO Box 2476, Melbourne,
Victoria, Australia 3001 2 Cooperative Research Centre for Advanced Composite Structures, 506 Lorimer Street, Fishermans Bend,
Victoria, 3207, Australia *Corresponding author. Email: [email protected]
Abstract: Existing vibration-based approaches for damage detection are qualitative. The present work explores the concept of an inverse method to obtain a quantitative characterisation of impact damaged structures, based on matching experimentally observed deflection or curvature profiles to parametric, model based, predictions of those profiles. Experimental and computational studies have been undertaken on laminated beam specimens containing delamination damage. It is shown that the curvature profiles cannot be correctly predicted by an inhomogeneity model in which the delaminated region is modelled as a region of reduced bending stiffness. Instead, it is essential to retain the geometrical feature of having at least one delamination. An inverse approach is implemented for estimating key model parameters based on matching finite element model predictions to full-field deflection or curvature profiles measured experimentally under forced vibration. It is indicated that it may be possible to optimise the detection and characterisation of specific types of damage by a judicious choice of the frequency and configuration of the applied loads.
Keywords: composite materials, delamination, impact damage, structural health monitoring.
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Session 11: SHM & NDT II Paper No: 177 Time: 1100 – 1120 Venue: Napier G04 Chair: Dr. Francis Rose Presenter: Wingkong Chiu
Integrating structural health monitoring into structural design Wern H. Ong1 and Wing K. Chiu1*
1 Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3800,
Australia *Corresponding author. Email: [email protected]
Abstract: The incorporation of in situ structural health monitoring is currently an after-thought used to address critical areas identified in testing or service. This paper reports on work seeking to allow for the implementation of in situ structural health monitoring (iSHM) at the design stage of critical structures. This work is intended for the design of future generation aircraft. The work presented describes a systematic redesign scheme based on Lamb wave technology. Strength and stiffness of the new structures are analysed to reveal any consequential changes. The results demonstrate a strong possibility that such a system is effective and feasible and comes at a tolerable cost to the structure. To demonstrate the efficacy of this proposed design scheme, a case study is presented where the fatigue critical location of structure representing the lower wing skin of an aircraft structure is presented.
Keywords: fatigue critical, finite element, in-situ structural health monitoring, lamb wave, non-destructive, modelling.
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Session 11: SHM & NDT II Paper No: 075 Time: 1120 – 1140 Venue: Napier G04 Chair: Dr. Francis Rose Presenter: Mehmet Yetmez
An experimental investigation of damaged plain-weave reinforced laminates using modal analysis Mehmet Yetmez1*, Hamza Erdogan1 and Hamit Aydin2 1 Department of Mechanical Engineering, Zonguldak Karaelmas University, Zonguldak, Turkey 2 Department of Mining Engineering, Zonguldak Karaelmas University, Zonguldak, Turkey *Corresponding author. Email: [email protected]
Abstract: In this study, dynamic analysis of carbon fiber plate including two surface cracks and a hole- notch is considered. Six carbon fiber-plain weave composite plates are provided by TAI-Turkish Aerospace Industry Inc., Turkey. Each of the six plates is 100×100 mm square and three of them are four-ply laminate (2.798 mm in thickness) and the last three are five-ply laminate (3.06 mm in thickness). Also, in order to compare the mechanical properties of carbon fiber-plain weave composite plates, static tensile tests are conducted. Then, vibration tests are performed to present the free vibration characteristics of clamped-free carbon fiber-plain weave composite plates. In addition to that, the prediction of resonant frequencies for the modal responses of four- and five-ply laminated carbon composite plates is studied. Corresponding to damage patterns, these experimental dynamic analyses consist of four parts: (1) Vibration analysis with no-damage, (2) Vibration analysis with hole-notch, (3) Vibration analysis with a hole-notch and a surface crack damages, (4) Vibration analysis with a hole-notch and two surface crack damages. For these purposes, an impact hammer with a force transducer is used to excite the undamaged or damaged plain weave composite plate through the selected points. After the excitation, the responses are obtained by an accelerometer. The vibration measurements are completed using a microprocessor-based data acquisition system.
Keywords: plain weave, damage pattern, hole-notch, surface crack, experimental modal analysis.
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Session 11: SHM & NDT II Paper No: 228 Time: 1140 – 1200 Venue: Napier G04 Chair: Dr. Francis Rose Presenter: Heung Fai Lam
Model updating and the detection of joint defects utilizing measured vibration data Heung F. Lam*, Hua-Yi Peng, Qin Hu and Jiahua Yang
Department of Civil and Architectural Engineering, City University of Hong Kong, HKSAR, China *Corresponding author: Tel: +852 3442-730. E-mail: [email protected]
Abstract: The paper reports an experimental case study on the use of measured vibration data for the detection of joint damage of steel frame structures. From the literature, one of the most common types of damage for steel frames is joint defect. When a building frame is under seismic load or strong wind load with large deformation, the bending moment at the beam-column connections and the column-base connections is very large. If the joint defects are not detected, they will accumulate. The joint behavior will change from rigid to semi-rigid and then to pin. As the load and moment distribution of the structure will be difficult from that in the design stage, there is no guarantee in structural safety. Structural damage detection is now still heavily rely on visual inspection, which is a local method. The results of damage detection are subjective and are depending very much on the experience of the inspector. The main purpose of this research is to develop a global method for joint defect detection for steel frames following the model updating approach. The proposed method aims in providing supplementary information on top of visual inspection to facility structural engineers in the remediate work related decisions.
In this study, all connections of the frame are considered as semi-rigid joint. They are modeled by linear elastic rotational spring. If the connection is intact, the rotational stiffness of the spring is very large (the behavior of the connection is close to rigid). Joint damage will reduce the rotational stiffness of the connection. This will be reflected from the vibration characteristics of the system. In the proposed method, the reduction in rotational stiffness is estimated by structural model updating technique based on the measured vibration data. This paper reports not only the theoretical development of the proposed method but also the experimental verification by a two-story steel frame under laboratory conditions.
Keywords: structural model updating, damage detection, vibration measurement, steel frame, semi-rigid connection.
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Session 12: Solid Mechanics I Paper No: 180 Time: 1020 – 1040 Venue: Napier 102 Chair: Prof. Paolo Lazzarin Presenter: Jinchen Ji
Super-harmonic resonance response of a quadratically nonlinear oscillator involving time delay Jinchen Ji* and Nong Zhang School of Electrical, Mechanical and Mechatronic Systems, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia *Corresponding author. Email: [email protected]
Abstract: Presence of time delays in nonlinear oscillators can not only cause instability of the trivial equilibriums but also generate rich dynamic behaviour including bifurcations and their interactions. For the nonlinear oscillators without external excitations, it has been shown that the trivial equilibrium of the nonlinear oscillators may lose its stability via a subcritical or a supercritical Hopf bifurcation and regain its stability via a reverse subcritical or a supercritical Hopf bifurcation as the time delay increases. The resultant periodic solutions from single Hopf bifurcations may be stable or unstable. When there are two pairs of purely imaginary solutions for the characteristic equation, double Hopf bifurcation is possible for the nonlinear oscillators involving time delay. Consequently, an interaction of two Hopf bifurcations can occur when the two critical time delays corresponding to the two Hopf bifurcations have the same value, which may result in either non-resonant or resonant Hopf-Hopf bifurcations.
Two-to-one resonant Hopf bifurcations are found to exist in a quadratically nonlinear oscillator involving time delay. The two resonant Hopf bifurcations create two respective periodic solutions for the nonlinear oscillator without external excitation. The collective behaviour of the oscillator includes stable initial equilibrium, stable periodic motion, stable quasi-periodic motion and unstable motion. The presence of a periodic excitation in the nonlinear oscillator can induce dynamic interactions between the weakly periodic excitation and the stable bifurcating solution. When the frequency of the external excitation and the frequencies of Hopf bifurcations satisfy a certain relationship, the dynamic interaction can produce resonant dynamic behaviour including primary resonance, super-harmonic and sub-harmonic resonances.
With the aid of normal form theory and centre manifold theorem as well as the method of multiple scales, the present paper studies the super-harmonic resonance response of a quadratically nonlinear oscillator involving time delay in the vicinity of the point of two-to-one resonances of Hopf-Hopf bifurcations. Three small perturbation parameters (which are called dummy unfolding parameters) are introduced to conveniently account for the variations of linear feedback gains and time delay near the point of double Hopf bifurcations. The effect of three small perturbation parameters on the forced response is discussed by studying the stability and bifurcations of fixed points of the averaged equations. Analytical results are validated by a comparison with those of direct numerical integration.
Keywords: nonlinear oscillator, quadratic nonlinearities, resonant Hopf bifurcations, time delay, two-to-one internal resonances.
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Session 12: Solid Mechanics I Paper No: 167 Time: 1040 – 1100 Venue: Napier 102 Chair: Prof. Paolo Lazzarin Presenter: Andrey Vasiliev
The analytical solution of contact problem about torsion of transversely isotropic elastic half-space with an inhomogeneous coating Andrey Vasilyev* and Sergey Aizikovich Don State Technical University, Scientific educational center “Materials”, 1 Gagarina sq., 344000, Rostov-on-Don, Russia. *Corresponding author. Email: [email protected]
Abstract: The problem about torsion by a circular indenter with flat base of transversely isotropic elastic half-space with an inhomogeneous coating is studied. Mathematical statement of a problem is formulated. The problem is reduced to dual integral equations by using integral transformations technique. The scheme of numerical construction of kernel’s transform of the integral equation is provided. Approximations of kernel’s transform are constructed by expressions of a special kind. Analytical solutions of a problem are constructed for these approximations. It is proved that the constructed solutions are asymptotically exact both at large and small values of characteristic dimensionless geometrical parameter of the problem. The distribution of displacements and contact stresses on depth in cases of continuous variation of elastic properties in coating and homogeneous coating are analyzed.
Keywords: contact problems, analytical methods, torsion, inhomogeneous coatings, transversely isotropy, functionally-graded materials.
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Session 12: Solid Mechanics I Paper No: 138 Time: 1100 – 1120 Venue: Napier 102 Chair: Prof. Paolo Lazzarin Presenter: Elena Pasternak
Homogenisation methods in mechanics of fragmented solids and hybrid materials Elena Pasternak1*, Arcady V. Dyskin2 and Igor Shufrin1,2 1 School of Mechanical and Chemical Engineering, University of Western Australia, Australia 2 School of Civil and Resource Engineering, University of Western Australia, Australia *Corresponding author. Email: [email protected]
Abstract: Fragmented solids – solids consisting of elements or fragments not directly connected to each other such that the structural integrity is maintained by a combination of kinematic constraints and compressive stresses at the boundary – play an important role in some natural and engineering systems. They are characterised by reduced shear stresses on the interfaces and the rotation and ‘elbowing’ of fragments. Fragmented solids are hybrid materials whose internal architecture (geometry) is a design parameter. First, we propose a finite element model of such a hybrid material with a small number of fragments followed by a continuum model for a large number of fragments. We find that the thermal stresses caused by non-uniform heating are substantially reduced in the hybrid as compared to the thermal stresses generated in the solid of the same geometry. The initial stage of block rotations involves delamination of inter-block contacts. A 1D continuum model of delamination (the fragmented beam) shows that delamination reduces the bending stiffness and increases the beam deflections. The reduction in bending stiffness is caused by the bending moment. The bending stiffness is affected by the cross-section geometry, however its influence is minor.
Keywords: topological interlocking, thermal stresses, delamination.
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Session 12: Solid Mechanics I Paper No: 026 Time: 1120 – 1140 Venue: Napier 102 Chair: Prof. Paolo Lazzarin Presenter: Filippo Berto
On the non singular higher order terms in bi-dimensional and three-dimensional engineering applications Filippo Berto1*, Paolo Lazzarin1 and Andrei Kotousov2
1 Department of Management and Engineering, University of Padova, Vicenza, Italy 2 School of Mechanical Engineering, the University of Adelaide, Australia *Corresponding author. Email: [email protected]
Abstract: In stress analysis of cracked plates, alongside the stress intensity factor which quantifies the singular stress component perpendicular to the crack plane, the role played in crack growth by the constant term parallel to the crack plane, called the T-stress, has been widely investigated by many researchers. There are, however, cases of practical interest where the influence on the stress field of the higher order terms in the series expansion for the crack tip stress field, is not negligible. The main aim of the present investigation is to present and apply a set of equations able to describe more accurately the stress components for those cases where the mode I and mode II stress intensity factors used in combination with the T-stress are unable to characterise with sufficient precision the complete stress field ahead the crack tip. The starting point is represented by the Williams’ solution (Williams, 1957) where stresses as expressed in terms of a power series. An example is investigated of a thin-thickness welded lap joint characterized by various joint width to thickness ratios, in the range of d/t ranging from 0.5 to 5. The present paper indicates that the local stresses as well as the strain energy averaged over a control volume which embraces the slip tip, can be evaluated with satisfactory precision only by taking into account a further four terms besides KI, KII and T-stress. Dealing with three-dimensional models the influence of higher order terms tied to mode II loading on the out-of-plane singular mode is investigated here dealing with cracked plates. An accurate analysis of mode II higher order terms and their effects on mode O is carried out by means of a large bulk of 3D numerical models.
Keywords: crack, elasticity, higher order terms, out-of-plane mode, strain energy density, stress intensity factors, T-stress, thickness effect.
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Session 12: Solid Mechanics I Paper No: 034 Time: 1140 – 1200 Venue: Napier 102 Chair: Prof. Paolo Lazzarin Presenter: Liangchi Zhang
An assessment of two statistical models for elastic contact analysis between rough surfaces Xiaoling Jin and Liangchi Zhang* School of Mechanical and Manufacturing Engineering, The University of New South Wales, NSW 2052, Australia *Corresponding author. Email: [email protected]
Abstract: This paper investigates the relative predictability of two statistical models for the elastic contact between two randomly rough surfaces. The first model, Model I, assumes that the contact between the two surfaces is equivalent to that between a composite surface and a plane. The second model, Model II, is a modified Greenwood-Tripp model which does not take the equivalent surface concept. It was found that the prediction differences from the two models would minimize when the interactions between surface asperities are taken into account. The effect of the inclusion of the asperity interactions on the Model I calculations is more obvious than that on the Model II. The contact force and area predicted by Model I are larger than those by Model II. Because of this, the mean contact stress from Model I is lower. The relative force prediction error increases with the separation of the mean planes, but decreases with the geometrical properties of the rough surfaces such as the asperity density, asperity radius and the standard deviation of the asperity height. The study found that Model I is more accurate in general because of its inclusion of both the contacts between summits and between shoulders and valleys.
Keywords: Statistical Model, Elastic contact, Rough surface, Contact interaction, Assessment.
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Poster Sessions Paper No: 024 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Leonard Koss
Mini- trampoline as a human structural vibration exciter Leonard L. Koss1*, Justin Rhodes2 and Vincent Rouillard2 1 Department of Mechanical and Aerospace Engineering, Monash University 2 School of Engineering and Science, Victoria University *Corresponding author. Email: [email protected]
Abstract: This paper outlines the results of experiments to demonstrate the use of a mini- trampoline as a structural vibration exciter. The exciter comes in two sections, the first is the human power source that provides vertical reciprocating motion and inertial mass, and the second is the trampoline membrane that is spring-tensioned. A human vibration exciter is thus established with the use of the mini-trampoline that can be used to determine floor structural stiffness values and frequency response functions amplitudes at the excitation frequency and its higher harmonics. The mini-trampoline static properties such as spring and membrane stiffness were determined from load-deflection tests and the dynamic properties such as natural reciprocating frequency and transmitted force were obtained using accelerometer and force transducers. The frequency range of the mini-trampoline can be varied between 2 to 2.6 Hz by employing people of various weights and through the use of different diameter discs on top of the membrane. The important point is that a vertical harmonic force of about 1 kN amplitude can be obtained at 2 Hz for testing of floors, foot bridges and roofs. This testing system is easily portable and measurements of force and response can be measured consecutively using only one accelerometer. Results of tests for stiffness and natural frequencies of a sample foot- bridge are presented.
Keywords: dynamic force, effective mass, force transmissibility, human vibration exciter, natural frequency, reciprocating frequency, structural stiffness.
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Poster Sessions Paper No: 043 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Salvinder Singh Karam Singh
Probabilistic approach in fatigue of crankshaft by using Markov Chain Model Nik Abdullah Nik Mohamed1*, Salvinder Singh Karam Singh1, Shakib Sharifian1 and Mohd Salmi Md Noorani2 1 Department of Mechanical and Material Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia 2 Faculty of Science and Technology, Universiti Kebangsaan Malaysia *Corresponding author. Email: [email protected]
Abstract: This paper describes the probabilistic method of using Markov chain model in determining the statistical relationship between bending and torsion on the effects of fatigue on the crankshaft. The crankshaft is subjected to cyclic loading which will tend to display the effects of fatigue which is stochastic in nature. This is because of the bending stresses due to self-weight of the piston, connecting rod and other components or misalignment of the piston and torsion stress. The Markov Chain was modelled to represent the probability for bending and torsion that would be acting on the crankshaft. It was observed from the model, that the loading on the crankshaft would be in a recurrent state where the loading would be returning or happening over time. Each probability was tested over a given time interval and the statistical analysis of the expected results were calculated and shown. Based from the statistical analysis, the coefficient of determination (R2) was calculated to be 81% where it is significant to conclude that the fatigue of a crankshaft is due to bending and supported by torsion. The effects of the statistical analysis can also be observed through the path of the crack propagation on the journal of the crankshaft which starts from the fillet region and propagates to the oil seal at a 45 degree angle.
Keywords: bending, markov chain, probability, stochastic, torsion.
90
Poster Sessions Paper No: 059 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Cătălin Iancu
An analytical – FEA approach to lifetime estimation of mining equipments Cătălin Iancu and Dan Dobrotă* Engineering Faculty, University “Constantin Brâncuşi” of Târgu-Jiu, Romania *Corresponding author. Email: [email protected]
Abstract: Existence of outdated equipment with lifetime expired, or in the ultimate life period, considering the high cost of replacement, makes rehabilitation reasonable to extend their life. From this point of view, is useful to find actual mechanical characteristics of materials, the period of service under consideration, assessing the possibility of life reserve, with an acceptable safety. First are presented background theoretical considerations on estimation of the life of a mining machine, using the calculation of fatigue crack propagation analysis, by Paris-Erdogan criterion and then Palmgren-Miner criterion, with an approximate method for estimating crack propagation. Based on the duration until a critical defect size, considering a real stress cycle, is established the periodicity of non-destructive testing of critical areas. This study is performed with a KSS Machine for coal moving, which had reached its lifetime period. In the second part of the paper are presented results of static analysis of specified mining equipment expertise, performed on the geometric model of mechanical analyzed structures, using SolidWorks, then for FEA COSMOS/Works. Furthermore, as later we will make a series of proposals to repair, rebuild and replacement, is necessary that theoretical results to be checked by inspections and mechanical tests on samples taken from specific areas of interest, revealed by FEA. Based on stages presented, proposals can be made to rebuild and replace for lifetime extension, and therefore saving great costs of new equipment. Furthermore, once completed the expertise, it can be developed a service specification, the warranty period and terms to re-examining.
Keywords: COSMOS/works analysis, criteria of fatigue cracking, life time, mining machinery, SolidWorks modeling.
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Poster Sessions Paper No: 178 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Houman Alipooramirabad
Prediction of welding residual stresses in flat plate(X80) Houman Alipooramirabad*, Andrei Kotousov and Reza Ghomashchi School of Mechanical Engineering, University of Adelaide, Australia *Corresponding author. Email: houman.alipooramirabad @adelaide.edu.au
Abstract: This research study used finite element technique (ANSYS) to analyse the residual stresses in flat plate(X-80).All the thermal and mechanical properties of the material till to liquid phase are described. In the 2-D ANSYS model plane 55 for thermal side and plane 182 for structural problem are used. The simulation results have been verified by similar works (publications) as well as with the simpler models which have been carried out. In order to perform simulations some assumptions in thermal analysis have been made such as using half-symmetry as well as applying temperature on surface of flat plate. The effects of heat input on structural constraints (both sides of geometry) and as a result the distributions of welding residual have been considered. The simulation is carried out for different mesh sizes and densities. The results show that mechanical results (mechanical stresses and strains) are very sensitive to the mesh shape.
Keywords: thermo-elastic-plastic, flat plate(X-80), residual stresses and finite element method
92
Poster Sessions Paper No: 194 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Hitoshi Takagi
Extraction and application of cellulose nanofiber from waste materials Hitoshi Takagi1*, Mohd Shahril Amin Bistamam2, Antonio N. Nakagaito1, and Jitendra K. Pandey1 1 Institute of Technology and Science, University of Tokushima, Japan 2 Department of Mechanical Engineering, University of Tokushima, Japan 3 Graduate School of Advanced Technology and Science, University of Tokushima, Japan *Corresponding author. Email: [email protected]
Abstract: Nanometre-scale cellulose fibres have shown much greater potential to improve mechanical and physical properties in a polymer composite system. The objective of this study is to extract the cellulose nanofibres from waste newspaper as a cellulosic source. Waste newspaper was treated chemically and physically in order to extract individualized cellulose nanofibres. Its ink colour was successfully removed by treating with a bleaching chemical. The combination of acid hydrolysis and mechanical treatments resulted in cellulose nanofibres with diameter ranging 10–40 nm. The reinforcing effect of obtained cellulose nanofibres was also investigated by composing with starch-based biodegradable resin. Commercially available cellulose nanofibre-reinforced composites were used as comparison to newspaper cellulose nanofibre (NPCNF) reinforced composites in mechanical properties tests. The result showed increases in mechanical properties for both reinforced composites. However, commercially available cellulose nanofibre-reinforced composited showed much greater enhancement in tensile strength than NPCNF-reinforced composites. It is suggested that this difference in mechanical performance is presumable derived from its fibre length, namely NPCNF is much shorter than commercially available cellulose nanofibre.
Keywords: cellulose, extraction, green composites, nanofiber, tensile properties.
93
Poster Sessions Paper No: 056 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Chong Y. Wong
Minimising solid particle erosion in an annular cavity Chong Y. Wong1* and Christopher Solnordal2 1 Commonwealth Scientific and Industrial Research Organisation, CPSE, Highett, Vic 3190 2 Commonwealth Scientific and Industrial Research Organisation, CMIS, Clayton, Vic 3168 *Corresponding author. Email: [email protected]
Abstract: A novel experimental study that combines a multilayer paint erosion technique and actual material loss experiments in the same test section for each experimental condition is reported. A 6061-T6 aluminium annular cavity with a step height of 12.75 mm and a streamwise length of 10.2 step-heights was tested in a 102.5 mm diameter gas-solids erosion rig using ambient air suspended with sand (4 ppm-vol, median size 198 m) in a bulk flow velocity of 80 m s-1 at a Reynolds number of 536,000. The study found that high rates of erosive wear on the cavity surface occur near regions where sudden change of flow direction and high relative velocities exist. These surfaces include the forward-facing step, the cavity surface immediately downstream from the backward-facing step, and the pipe surfaces upstream and downstream of the cavity. These measurements were made possible by high-resolution surface profile measurements. A CFD analysis of erosion rate on the forward-facing step has shown that erosion can be predicted to within 25% of experimental measurements using a model with coefficients based on these same semi-sharp particles impacting an aluminium surface. Having validated the erosion technique, CFD analysis was further used to examine configurations that minimise sand erosion within the cavity.
Keywords: aluminium, cavity flows, CFD, sand erosion, wear predictions.
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Poster Sessions Paper No: 087 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Alin Nioaţă
Experimental study for electrochemical discharge machining (ECDM) cutting using a stratified disk transfer Alin Nioaţă* Engineering Faculty, University “Constantin Brâncuşi” of Târgu-Jiu, Romania *Corresponding author. Email: [email protected]
Abstract: Electrochemical discharge machining (ECDM) is the superposition in time and space within the operating clearance, of electrochemical erosion and electrical erosion processing.The paper presents a stratified disk transfer object which allows to introduce the operating fluid inside. The number and size of slits is calculated depending on the necessary flow of the operating fluid in the processing clearance. The material of the samples used for making the experiments is alloy steel X40CrMoV5-1, and the material of the transfer object is general steel. Experiments have revealed a number of conclusions regarding output parameters dependence (processing productivity, processed surface roughness, deviation from flatness, etc.) on the input ones (electric stress, pressure, etc) to the processing process (in particular, on cutting) through electrochemical discharge machining (ECDM). Analyzing the experimental data we notice that if the voltage and pressure increase processing productivity, roughness and flatness deviation also have high values. This is why, as a result of optimization, a group of parameters is achieved with higher values than processing productivity under the conditions of a lower roughness, on condition that flatness deviation be included within the limitations.
Keywords: electrochemical discharge machining, flatness deviation, pressure, processing productivity, roughness, voltage.
95
Poster Sessions Paper No: 212 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Roslina Mohammad
Transient response for different support of pipes with flowing medium subjected to impulse loading Roslina Mohammad1*, Andrei Kotousov2, John D. Codrington2 1 Department of Mechanical Engineering, UTM Razak School of Engineering and Advanced Technology,
Universiti Teknologi Malaysia International Campus, Kuala Lumpur, Malaysia 2 School of Mechanical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia *Corresponding author. Email: [email protected]
Abstract: The primary aim of this study is to investigate the effects of a flowing medium on the transient response for different types of pipes subjected to dynamically applied loading. The types of support include a cantilever pipe, encastre pipe, propped cantilever pipe, and simply supported pipe. The topic is very important in many industrial and military applications including offshore structures, oil and gas, power stations, petrochemical and defence industries where critical pipe components transporting a gas or liquid can be subjected to impact loading due to an accident. In many previous studies, such effects were largely ignored, simplified or considered negligible. The conducted study demonstrated that in many practically important cases, the influence of flowing medium on transient response is not small and has to be taken into consideration. The classical Bernoulli-Euler beam theory is adopted to describe the dynamic behaviour of an elastic pipe and a new governing equation of a long pipe transporting gas or liquid is derived. This governing equation incorporates the effects of inertia, centrifugal and Coriolis forces due to the flowing medium. This equation can be normalised to demonstrate that only two non-dimensional parameters govern the static and dynamic response of the system incorporating a pipe and flowing medium. The transient response of this system is investigated based on a standard perturbation approach. Further, a numerical method utilising the finite difference method is developed and applied to investigate the dynamic response of pipes with different support. It is demonstrated that the previous dynamic models which largely ignore the internal flow effects and interactions between the flow and structure normally produce a large error and are inapplicable to the analysis of many practical situations.
Keywords: cantilever pipe, encastre pipe, flow-structure interactions, flowing medium, impulse loading, propped cantilever pipe, simply supported pipe, transient response, transporting gas or liquid.
96
Poster Sessions Paper No: 203 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Thomas Lillicrap
Finite element modelling of heat exchange in the stroke-affected brain during therapeutic hypothermia Thomas Lillicrap1,2,3*, Murat Tahtalı3, Andrew Neely3, Christian Lueck1,2, and Xiaofei Wang3 1Neurology Department, The Canberra Hospital, Canberra, ACT, Australia 2 School of Medicine, Australian National University, Canberra, ACT, Australia
3School of Engineering and Information Technology, University of New South Wales Canberra, Canberra, ACT, Australia.
*Corresponding author: Email [email protected]
Abstract: Hypothermia is a promising neuroprotectant for the treatment of ischaemic stroke. Current trials of hypothermia rely on cooled blood to reduce the temperature of ischaemic brain tissue. However, since blood flow to the ischaemic brain tissue is compromised, there is likely to be spatial variation in the rate and level of cooling accomplished by cooled blood in this tissue. Finite Element Modelling was used to investigate variation the effectiveness of tissue cooling as a result of spatial variations in cerebral blood flow and cerebral metabolic rate. These factors were found to affect the absolute level of tissue cooling achievable, but not the rate of cooling. This study suggests that pharmaceutical reduction of cerebral metabolic rate may improve the effectiveness of current cooling techniques by minimising spatial variation in brain temperature as a result of impaired blood flow, thereby potentially improving patient outcome.
Keywords: Finite Element Modelling, Hypothermia, Pennes Bioheat Equation, Stroke.
97
Poster Sessions Paper No: 057 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Pouria Aryan
Using 3D Scanning laser vibrometre for imaging delimitation defects in composites Pouria Aryan1, Ching-Tai Ng2 and Andrei Kotousov1 1 School of Mechanical Engineering, University of Adelaide, Australia
2 School of Civil Environmental and mining Engineering, University of Adelaide, Australia
*Corresponding author. Email:[email protected]
Abstract: Guided lamb wave structural health monitoring is widely used as one of the most reliable tools for damage identification in composite structures. The application of guided Lamb Waves to detect inner delimitations in composite structures is presented in this paper. Due to anisotropic behaviour and complex geometry there is no suitable analytical solution for the analysis of scattering the lamb waves in composite laminates. This study employs a three dimensional explicit finite element (FE) method to simulate and predict scattering of the lamb wave in a composite plate and the results are compared with experimental measurements using a three dimensional laser vibrometre.
Keywords: Structural health monitoring, guided waves, non-destructive evaluation, composite materials.
98
Poster Sessions Paper No: 118 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Dan Dobrotă
Research on the influence of rubber waste and devulcanization technology on the characteristics of reclaimed rubber Dan Dobrotă1 and Gheorghe Amza2* 1 University “Constantin Brâncuşi” of Târgu-Jiu, Romania 2 University Polytechnic of Bucharest, Romania *Corresponding author. Email: [email protected]
Abstract: The problem of recovery of the waste rubber is one of the current global economic priorities. Rubber regeneration is a high recovery of rubber waste and for this purpose the research was aimed at establishing the types of reclaimed rubber that can be obtained from different types of waste. The reclaimed rubber types obtained were divided into 6 categories (A, B, C, D, E, F) and for each of them have been determined five characteristics (tensile strength, elongation at break, hardness, Mooney viscosity, ash percentage) which has allowed the establishment of an overall quality indicator for each type of reclaimed rubber (GIQ). Also, the 6 types of reclaimed rubber were obtained with two different technologies for regeneration, obtaining superior general indicators of quality for the regeneration technology which is based on the vacuum of the de-vulcanization autoclave after desulphurization. Thus the technological flow was improved and a certain auxiliary operation was introduced after de-vulcanization and desulphurisation the vacuum of the autoclave by coupling it to a vacuum installation. By applying this new technology, the removal of a quantity of residual water of 150 litters for each batch of autoclave was obtained (900 kg). By achieving the vacuum of the autoclave, the resulting de-vulcanized rubber was much more homogeneous and thus refining time was reduced by about 30%, and this reduction also determined an appropriate reduction in specific consumption.
Keywords: mechanical properties, processing technologies, raw materials, reclaimed rubber, rubber.
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Poster Sessions Paper No: 191 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Andrey Kartavykh
Tailored microstructure creation of TiAl-based refractory alloys within VGF solidification Andrey V. Kartavykh1*, Vladimir P. Ginkin2 and Svetlana M. Ganina2 1 Technological Institute for Superhard and Novel Carbon Materials (TISNCM), 7a Centralnaya str.,142190
Troitsk, Moscow city, Russia 2 Institute for Physics and Power Engineering (IPPE), Bondarenko sq.1, 249033 Obninsk, Russia *Corresponding author. Email: [email protected]
Abstract: The work is aimed at the study of the formation and refinement of primary microstructure appearing in the refractory lightweight structural TiAl-based intermetallics during their solidification from the melt. The alloy with Ti-46Al-8Nb (at.%) nominal composition is selected for applied study in microstructure engineering. For tailored microstructure development, the Directional Solidification (DS) of pre-synthesized alloy was performed in the vertical multizone electro-furnace by Vertical Gradient Freezing (VGF) power-down technique in pure argon environment. Both columnar-dendrite, and equiaxed-granular reproducible as-cast microstructures have been produced in DS ingots, basing onto Columnar-to-Equiaxed Transition (CET) diagram exploration. Particular attention was paid further to equiaxed microstructure improvement by combination of modifying doping of alloy with boron grain refiner and VGF processing. As a result the perfect inoculated microstructure of Ti-44Al-7Nb-2B (at.%) ingots was produced with 120 μm mean grain diameter, low scattering of dimensional characteristics and high tolerance to DS process parameters variation. DS samples were examined by SEM microanalysis along with EBSD and Auger spectrometry of boride particles in the alloy matrix. The nature, state and exact composition of precipitated borides are discussed along with the nucleation mechanism in relation to the literature data.
Keywords: grain refinement, microstructure, nucleation, precipitation, solidification, TiAl-based intermetallics, Vertical Gradient Freezing (VGF).
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Poster Sessions Paper No: 207 Venue: Napier Undercroft and Overcroft / Foyers Presenter: Vladimir Ginkin
Numerical simulation of multicomponent alloy solidification Vladimir P. Ginkin1*, Svetlana M. Ganina1 and Andrey V. Kartavykh2 1 Institute for Physics and Power Engineering (IPPE), Bondarenko sq.1, 249033 Obninsk, Russia 2 Technological Institute for Superhard and Novel Carbon Materials (TISNCM, Moscow branch), B.Tolmachevsky per.5, 119017 Moscow, Russia *Corresponding author. Email: [email protected]
Abstract: A non-equilibrium model of multicomponent melt solidification has been developed in which a Stefan problem with two boundaries is solved numerically, the boundaries being between the solid phase and the two-phase transition zone and between the two-phase transition zone and the liquid phase. The two-phase zone is represented as a porous medium with variable porosity. Account is taken of the additional force resisting the melt flow due to porosity and introduced by analogy with Darcy’s law. Computer simulation has been performed of the experiment on Sn-20 wt.%Pb binary alloy solidification by the method of downward-directed crystallization along the gravity vector. Shown in the paper are the results of a quasi two-dimensional benchmark experiment on horizontal (i.e., at the right angle to the gravity vector) directional solidification of a binary Sn-3 wt.%Pb alloy. The calculations were done using two crystallization models: the equilibrium model and the non-equilibrium one. It is shown that the non-equilibrium model gives a better description of the thermal field evolution and solute distribution caused by natural convection.
Keywords: solidification, binary alloy, dual-phase region, macrosegregation, convection, heat-mass transfer, modelling, comparison with experimental results, the columnar-to-equiaxed transition (CET).
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Session 14: Automotive Research I Paper No: 159 Time: 1540 – 1600 Venue: Napier G03 Chair: A/Prof. Dianne Hesterman Presenter: Paul D Walker
Dynamics and control of gear shifts in a two speed electric vehicle Paul D. Walker1*, Nong Zhang1, Bo Zhu2 and Salisa A. Rahman3 1 Faculty of Engineering and IT, University of Technology, Sydney, Australia 2 Beijing Electric Vehicles, Beijing, China 3 Faculty of Science and Technology, University of Malaysia Terengganu, Malaysia *Corresponding author. Email: [email protected]
Abstract: Electric vehicles have become an alternative to conventional and hybrid electric passenger vehicles, with the capability to provide higher overall powertrain efficiencies through the omission of conventional combustion engines. However, as a result of lower battery energy density as compared to fossil fuels, electric powertrains have limited range capabilities, leading to a phobia of electric vehicles and limited consumer acceptance. Furthermore, small electric motors typically cannot achieve the diverse functionality of conventional vehicles, most particularly for vehicle performance and grade climbing in comparison to vehicle range. As a result, multi-speed transmissions have been suggested as one strategy to improve the powertrain performance and increase the functionality of electric vehicles. By increasing the number of gear ratios the motor can operate under higher efficiencies for a wider range of vehicle speeds. The vehicle can then be designed to operate at a more diverse range of operating conditions, increasing the speed range and torque deliverable at lower speeds.
To realise this objective there is a necessity to provide gear shift strategies unique to electric vehicles, delivering high quality gear shifts without relying on conventional vibration isolators such as torque converters or torsional dampers. This paper presents modelling, simulation, and control of a two speed electric vehicle. Demonstrating through enhanced precision of torque estimation and control in the electric machine it is possible to minimise powertrain response during and after gear shift transients, thereby improving driver comfort. The contents of this paper will therefore provide a detailed framework for powertrain modelling with electric vehicles, identify appropriate shift strategies for stepped automatic EVs, integrate these to develop shift control algorithms, and finally provide simulation results for up shift transients. Results demonstrate that it is possible to both improve post shift transient response of the powertrain and reduce the inertia phase of gear shift using the proposed methods.
Keywords: control, dynamics, dual clutch transmission, electric vehicle, gear shift.
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Session 14: Automotive Research I Paper No: 187 Time: 1600 – 1620 Venue: Napier G03 Chair: A/Prof. Dianne Hesterman Presenter: Nong Zhang
Empirical analysis of a roll-plane hydraulically interconnected suspension system under vehicle articulation mode Holger M. Roser*, Lifu Wang and Nong Zhang School of Electrical, Mechanical and Mechatronic Systems, University of Technology Sydney, Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: This paper presents the findings of an empirical analysis of a roll-plane Hydraulically Interconnected Suspension (HIS) system under vehicle articulation mode excitation. The articulation mode of a four-wheel vehicle describes the in-phase motion of two diagonal opposed wheels, with adjacent wheels moving out of phase. This mode is critical for better off-road vehicle handling, particularly in utility vehicles; nonetheless, only little research has been conducted addressing this issue. Although a soft articulation mode is desired for enhanced road-holding, the widely used anti-roll bars, necessary for increased roll stiffness, also make the articulation mode stiffer. As a result, one or more wheels may lose ground contact on uneven surfaces, compromising vehicle stability and safety.
Roll-plane HIS systems are capable of decoupling vehicle roll from articulation at full-car level; thus HIS systems are attracting ongoing attention from researchers. A comparative experimental study of HIS and anti-roll bars has been carried out on a purpose-built four-post dynamic suspension test rig in order to evaluate vehicle dynamic performance in both roll and articulation modes. For this the vehicle is tested at two different configurations: conventional suspension and roll-plane HIS. Consequently, it has been demonstrated that the HIS system offers a significantly softer articulation mode compared to conventional anti-roll bars, improving vehicle handling and safety. A detailed analysis and discussion of test results conclude this paper.
Keywords: hydraulically interconnected suspension, vehicle articulation mode, vehicle stability and safety.
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Session 14: Automotive Research I Paper No: 129 Time: 1620 – 1640 Venue: Napier G03 Chair: A/Prof. Dianne Hesterman Presenter: Andrew Guzzomi
Using canonical variate analysis to detect engine misfires Ben Speijers, Dianne Hesterman and Andrew Guzzomi*
School of Mechanical and Chemical Engineering, University of Western Australia, Western Australia *Corresponding author. Email: [email protected]
Abstract: The application of canonical variate analysis as a method for identifying engine misfires is investigated in this paper. Canonical variate analysis, also known as discriminant analysis, is a form of multivariate statistics that is used to determine whether a chosen set of predictors can be used to differentiate between different cases. Successful predictors can then be used to develop decision trees for automatic case identification. In the presented work, the first six engine harmonics were used as the predictors. The crank velocity was measured at the free end of the crankshaft on a six-cylinder engine using a torsional laser vibrometer. The laser vibrometer provides more accurate torsional vibration information from the crankshaft than a rotary encoder and requires significantly lower sample rates. A tachometer was used to indicate TDC on cylinder 1 and served as crank angle reference for subsequent data processing. Misfires in single and multiple cylinders were experimentally induced. The recorded time data was converted to the frequency domain and the first six engine orders were chosen to capture the important frequency components of the engine behaviour. Canonical variate analysis was then applied to identify relationships between the relative magnitudes of these harmonics for normal operating conditions and also for different misfire events. Two average rotational speeds were analysed, 1300rpm and 2500rpm. It is shown that the method successfully distinguished between normal and fault conditions and located single and multiple cylinder misfires. At the lower rotational speeds, it was possible to determine the location of most single misfires. The method could not distinguish between cylinders 1 and 2, due to some overlap in the signals. Cylinder 1 was closest to the measurement position and an alternative measurement position may be required to clearly discriminate between cylinders 1 and 2. Further work is also needed to determine the suitability of this technique to the lower resolution encoder data typical of current state-of-the-art real time analysis. The results presented indicate that canonical variate analysis may provide some advantages over real-time domain methods, especially for engines with high cylinder count and running at nominally steady-state conditions.
Keywords: fault detection, engine condition monitoring, torsional vibration, canonical variate analysis, signal processing.
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Session 14: Automotive Research I Paper No: 155 Time: 1640 – 1700 Venue: Napier G03 Chair: A/Prof. Dianne Hesterman Presenter: Nong Zhang
Modelling and parameter estimation of an active hydraulic suspension using experimental method Lifu Wang1*, Nong Zhang1, and Haiping Du2 1 School of Electrical, Mechanical and Mechatronic Systems, Faculty of Engineering and Information Technology,
University of Technology, Sydney 2 School of Electrical, Computer and Telecommunications Engineering, University of Wollongong *Corresponding author. Email: [email protected]
Abstract: This paper presents the modelling and parameter estimation of a novel low-cost active hydraulically interconnected suspension through experimentation. The estimated model, combined with a half-car model in state-space, is employed to derive a H∞ control strategy for vehicle body roll control and verified in numerical tests. As an attempt to make the active suspension more affordable, the paper presents a safety-orientated, low cost hydraulic active suspension with interconnected circuits, through which the four hydraulic actuators are controlled by only one pressure valve, which significantly reduced the initial cost comparing to conventional active suspensions with independently controlled actuators. The pressure control unit, as the vital part of the active suspension, is designed, implemented and assembled onto the test vehicle with the existing cylinders and hydraulic piping.
An appropriate model and parameters of this pressure unit is essential for model-based optimal controller, since it has to be simple enough for the controller design and also capture the system dynamic characteristics. The empirical approach used for derive the model is presented, and the estimated model matches the test data well in the Bode graph. The derived H∞ controller based on the half-car model and the active suspension model is then verified by a numerical example. Discussions and suggestions for future work conclude the paper.
Keywords: model estimation, vehicle dynamics, active suspension, pressure control unit, Bode graph.
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Session 15: Composites II Paper No: 054 Time: 1540 – 1600 Venue: Napier G04 Chair: Prof. Chun Wang Presenter: Shankar Kalyanasundaram
On the forming behaviour of woven thermoplastic composite materials Sudharshan Venkatesan and Shankar Kalyanasundaram* Research School of Engineering, The Australian National University, Canberra, Australia *Corresponding author. Email: [email protected]
Abstract: This study investigates the feasibility of using the stamp forming technique for the processing of thermoplastic, recyclable composite materials. Two composite materials with different fibre reinforcements were studied; an all-Polypropylene composite material (Curv®) and a Glass Fibre Reinforced Polypropylene composite material (Twintex®). The investigation includes a detailed experimental study based on strain measurements using a non-contact optical measurement system in conjunction with stamping equipment to record and measure the formability of the thermoplastic composites in real time. The evolution of the meridian strain was used to develop an understanding of the effect of fibre stiffness on the forming behaviour of the two composite materials used. This investigation also compares the formability of the composite materials with a monolithic aluminium alloy. The results indicate that composite materials can exhibit comparable and sometimes superior formability compared to monolithic aluminium.
Keywords: composite materials, stamp forming, 3D photogrammetry, meridian strain, aluminium.
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Session 15: Composites II Paper No: 215 Time: 1600 – 1620 Venue: Napier G04 Chair: Prof. Chun Wang Presenter: Gayan Kahandawa
Detecting delamination in a composite structure using an embedded FBG – AE hybrid system Gayan C. Kahandawa*, Mohammad Z. Hafizi, Jayantha A. Epaarachchi and K.T. Lau
Faculty of Engineering and Surveying, Centre of Excellence in Engineered Fibre Composites, University of Southern Queensland, Toowoomba QLD 4350, Australia *Corresponding author. Email: [email protected] Abstract: Distorted spectra of Fibre Bragg Gratings (FBG) sensors have been using in most of research on identifying delaminations in composites which is the most common cause of failures of laminated composite structures. However, it has been shown that there are multiple causes which can produce a similar response spectrum of an FBG sensor. As a consequence an integrated additional monitoring system would enhance the prediction power of FBG based monitoring system. In this research paper we introduce a “FBG-AE hybrid system” concept for the detection of delaminations in composite structures which uses same FBG sensor network for monitor damage using two independent responses from the sensors. The proposed system use spectral responses from FBG sensors and extract strain and acoustic emission data for monitoring purpose. The proposed concept has experimentally investigated with convincing results.
Keywords: acoustic emission, FBG sensors, FRP structures, structural health monitoring.
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Session 15: Composites II Paper No: 204 Time: 1620 – 1640 Venue: Napier G04 Chair: Prof. Chun Wang Presenter: Ling Yin
Influence of microwave energy on mechanical strength in sugarcane Ling Yin1*, Parmeet Singh1, Graham Brodie2, Madoc Sheehan1, Mohan V. Jacob1 1 School of Engineering & Physical Sciences, James Cook University, Townsville, QLD 4811, Australia 2 Melbourne School of Land and Environment, University of Melbourne, Dookie, VIC 3647, Australia *Corresponding author. Email: [email protected]
Abstract: Sugarcane processing produces cane sugar (sucrose) from freshly harvested sugarcane through mechanical milling processes such as shredding and crushing. As sugarcane strength increases, not only do shredding and crushing forces, torques, energy, and temperatures increase but shredder hammer tools and crushing rollers also wear more rapidly. These cause high energy consumption, and high operation and maintenance costs in the sugar industry. To make sugarcane more processable, we employed heat treatment of sugarcane using microwave energy to soften sugarcane prior to its mechanical processing. In this paper, we report our investigation of the influence of microwave heating on the mechanical properties of sugarcane stalk internodes, including the Young’s modulus, the yield strength and the ultimate strength during compressive testing. The results show that microwave heat treatment significantly reduces mechanical strength and stiffness of sugarcane so that treated sugarcane stalks become more processable in mechanical milling processes.
Keywords: deformation, fracture, stiff, strength, sugarcane.
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Session 15: Composites II Paper No: 062 Time: 1640 – 1700 Venue: Napier G04 Chair: Prof. Chun Wang Presenter: Sebastian Davey
Finite element analysis of the formability of carbon fibre/PEEK composite sheets Sebastian Davey1*, Raj Das2, Wesley Cantwell3 and Shankar Kalyanasundaram1
1 Research School of Engineering, Australian National University, Canberra, Australia 2 Department of Mechanical Engineering and Centre for Advanced Composite Materials, University of Auckland,
New Zealand 3 Centre for Materials and Structures, University of Liverpool, United Kingdom *Corresponding author. Email: [email protected]
Abstract: CF/PEEK composites are currently employed in specialty applications such as medical implants. Despite their excellent mechanical properties, prohibitive material and fabrication costs prevent this composite from becoming broadly utilised in manufacturing. The development of rapid forming processes for CF/PEEK composites could substantially reduce the cost of this material and allow it to replace traditional materials in many high-performance applications. In this study, a finite-element model for simulating CF/PEEK forming was validated using stamp forming experiments. Circular composite blanks were formed to 15mm using a hemispherical punch, with various blankholder forces partially restraining the edge of the blank. Strains on the lower surface of the blank were measured during forming and compared to those obtained in the numerical simulations. At small forming depths, the finite-element model was found to accurately predict the strain behaviour of the composite. At larger depths the strain at an angle of 45 to the carbon fibres was under-predicted. This was presumably caused by non-linear stress-strain behaviour developing in the later stages of forming. The validation of this model is an important step in developing rapid forming processes for CF/PEEK composites. If the material’s forming behaviour can be accurately predicted, then its forming capabilities can be fully characterised. As a result, rapidly formed CF/PEEK could be deemed a suitable material in many engineering applications.
Keywords: carbon fibre reinforced polymers, finite-element modelling, stamp forming, real-time strain measurements.
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Session 16: Automotive Research/ Sustainability Paper No: 117 Time: 1540 – 1600 Venue: Napier 102 Chair: A/Prof. Philip Mathew Presenter: Vahid Vakiloroaya
Experimental study of anew solar-assisted air-conditioner for performance prediction and energy saving Vahid Vakiloroaya1*, Quang P. Ha1 and Bijan Samali2 1 School of Electrical, Mechanical and Mechatronic Systems, University of Technology, Sydney, Australia 2 School of Civil and Environmental Engineering, University of Technology, Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: This paper aims to analyse the performance of a new solar-assisted direct expansion air-conditioner and to demonstrate its capability of energy savings and ecological conservation. Here, an integrated flat collector storage system as well as an immersed piped coil is equipped with the direct expansion evaporator to raise the superheat temperature entering the variable speed compressor, causing a smaller duty cycle of the compressor and a slight increase in itssuction pressure, and hence, reduce its energy consumption. Water in the flat solar collector is in contact with the collector’s absorbing surface and therefore, heat is transferred to the water and then to the refrigerant in the immersed heat exchanger. Once the room has achieved its desired temperature, the compressor turns off while room cooling will continue until the refrigerant pressure within the circulation loop fails to maintain the desired temperature. The system advantage is that heat can be imparted into the refrigerant via the flat plate collector, so the compressor can remain off longer. This process justifies up to 40% energy savings. Mathematical models will be derived for the system components. These models are then validated against by using experimental data. For this, the system is equipped with several sensors and data-loggers. The models are coded into a transient simulation tool using FORTRAN. Predictions from the model are obtained over a very wide range of operating conditions and exhibit a good coincidence with experimental results. They serve to determine the principal parameters that remain most effective in performance enhancement in terms of reduction of energy consumption and greenhouse gas emission.
Keywords: energy saving, experimental study, performance prediction, solar-assisted air-conditioner.
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Session 16: Automotive Research/ Sustainability Paper No: 092 Time: 1600 – 1620 Venue: Napier 102 Chair: A/Prof. Philip Mathew Presenter: Gheorghe Amza
Research on determining the coefficient of environmental pollution produced by automatic submerged arc welding Gheorghe Amza1 and Dan Dobrotă2* 1 Polytechnica University of Bucharest, Romania 2 “Constantin Brancusi” University of Târgu Jiu, Romania *Corresponding author. Email: [email protected]
Abstract: Assembly by welding is a highly polluting process technology, especially in the atmosphere and soil. The main phenomenon that occurs in arc column and which is directly related to environmental pollution process is the phenomenon of dissociation of gas. Thus, gases such as hydrogen, nitrogen, oxygen and carbon dioxide are dissociated in the arc column at high temperatures. For assessment and analysis of the actual environmental impact of submerged arc welding machines, equipment was chosen as fitness for purpose and built an original experimental stand, which shows, finally, an equation of balance of process materials as close to reality as accurately and assess the correct environmental impact. Equipment used to detect gas resulting from the welding operations was analysis equipment model Madura GA 40 PLUS, and most of welded seams on welded construction made by the analyzed organization are taken with A2 Multitrac - SAF. The area was sealed to reduce gas leaks or fumes. To determine the environmental impact of the submerged arc welding process was carried out an experimental program that ultimately allow optimization of welding in terms of coefficient of pollution, that includes the steps described below. The basic material where the welding seams were deposited under certain conditions was a common carbon steel S235JR mark. Filler material was in the form of wire-electrode developed in coils, of diameters between 1.0 mm and 12.5 mm.
Keywords: automatic welding, gas emissions, pollution coefficient, welding parameters.
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Session 16: Automotive Research/ Sustainability Paper No: 018 Time: 1620 – 1640 Venue: Napier 102 Chair: A/Prof. Philip Mathew Presenter: Daniel Ainalis
Evaluation of experimental techniques for establishing vehicle suspension characteristics Daniel T. Ainalis*, Vincent Rouillard and Michael A. Sek School of Engineering and Science, Victoria University, Melbourne, Australia *Corresponding author. Email: [email protected]
Abstract: This paper presents preliminary laboratory work that is part of a broader research initiative aimed at estimating the dynamic characteristics of wheeled vehicles using only in-service response data. In order to validate any proposed techniques, it is important that the true dynamic characteristics or Frequency Response Function (FRF) of the test vehicle(s) be known accurately. In order to isolate multiple-input and drive-train noise effects; a simple, single-wheeled, towable test vehicle representing a quarter car was commissioned. This paper focuses on the evaluation and comparison of spectral-based experimental methods representing averaged road elevation profiles to establish vehicle dynamic characteristics. The approaches examined make use of a vibration table to investigate the effect of various road spectra on obtaining consistent estimates of the dynamic characteristics of the test vehicle. The results presented in this paper show that, due to nonlinear behaviour of the suspension system, the system’s dynamic characteristics are highly dependent on excitation type and level. The paper concludes that estimating the dynamic characteristics of a simple quarter-car vehicle is not straightforward and there are several challenges identified for the next phase of the research which is to estimate these dynamic characteristics using only in-service response data during normal operation.
Keywords: damping, frequency response function, natural frequency, road-friendliness, road-friendly vehicles.
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Session 16: Automotive Research/ Sustainability Paper No: 052 Time: 1640 – 1700 Venue: Napier 102 Chair: A/Prof. Philip Mathew Presenter: Tandy Pok
Literature review of pedestrian injury severity with vehicle impact speeds and the development of curves to predict pedestrian injury likelihood (AIS 1 to AIS 6) versus vehicle impact speeds Tandy W. P. Pok*, Nikola Josevski, Tia L. Orton, Andreas L. Sandvik, Christopher M. Jones and Shane A. Richardson Delta-V Experts, 377 St Georges Road, Fitzroy North VIC 3068, Australia *Corresponding author. Email: [email protected]
Abstract: In the area of forensic engineering, the relationship between vehicle impact speed and the severity of pedestrian injury is an area of interest. However, the research that is available tends to classify vehicle impact simplistically in terms of either minor injury or serious to fatal injury. Specific, individual classifications of injury are typically not assessed. There appears to be a lack of published data which illustrates the holistic range of injury effects using the Abbreviated Injury Scale (AIS 1 to AIS 6) with respect to vehicle impact speed.
This paper reviews and extracts the published data correlating specific pedestrian injury severity with vehicle impact speeds. The body of extracted data sets have been combined to theoretically quantify pedestrian injury severity versus vehicle impact speed. The data sets are used to develop a series of curves illustrating the probability of a pedestrian sustaining an AIS 1 through to AIS 6 injury severity as a function of vehicle impact speed.
Keywords: abbreviated injury scale (AIS), impact speed, injury severity, pedestrian, vehicle.
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Session 17: Fluid-Structure Paper No: 029 Time: 1020 – 1040 Venue: Napier G03 Chair: Dr. Sook-Ying Ho Presenter: Mei Cheong
Single-image attenuation corrections to facilitate instantaneous planar imaging of densely seeded particle-laden flows Mei C. Cheong*, Cristian H. Birzer and Timothy Lau School of Mechanical Engineering, University of Adelaide, Australia *Corresponding author. Email: [email protected]
Abstract: Planar Nephelometry is a laser-based technique developed to determine instantaneous local number densities of particles (or droplets) in a suspension or flow. Planar Nephelometry infers particle number density by the Mie-Lorenz scattering of laser light from the particle surface. A major advantage of Planar Nephelometry is that is does not need to resolve individual particles and therefore it is possible to have a large image viewing area. However, if the local number density of particles is sufficiently high, the laser light experiences significant attenuation which needs to be corrected to ensure accurate concentration measurements. Laser attenuation experiments were conducted using a tank with neutral density spherical particles suspended in water. Results for particles at various homogeneous concentrations were obtained. Attenuation of light by the suspended particles was determined using the scattering of light from a polymer strip at the down-beam location of the tank. The current paper presents the application of the Planar Nephelometry technique and post-processing methodology corrections required when using a single camera to obtain instantaneous planar particle concentrations.
Keywords: laser attenuation correction, laser diagnostics, particle-laden fluids.
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Session 17: Fluid-Structure Paper No: 069 Time: 1040 – 1100 Venue: Napier G03 Chair: Dr. Sook-Ying Ho Presenter: Farzin Ghanadi
A review of skin friction drag reduction within the turbulent boundary layer Farzin Ghanadi*, Maziar Arjomandi, Anthony C. Zander and Ben S. Cazzolato School of Mechanical Engineering, University of Adelaide, Australia *Corresponding author. Email: [email protected]
Abstract: Skin friction drag reduction in the turbulent boundary layer has high potential benefits which have been a subject of much interest. From general point of view this paper gives an overview of various methods to control the turbulent boundary layer. Primary section of the paper highlights the importance of skin friction drag reduction in turbulent boundary layers, followed by brief discussion of turbulence and Reynolds shear stress production process in the near wall region. Since there are several ways to suppress the instabilities, which naturally occur in the turbulent boundary layer, lots of control techniques have been investigated in next sections. The present article provides an up-to-date summary of passive and active mechanisms responsible for viscous drag reduction. Furthermore, the implications of previous controller and the success or limitations of various methods are discussed.
Key words: viscous drag reduction, spanwise vortices, low speed streaks.
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Session 17: Fluid-Structure Paper No: 100 Time: 1100 – 1120 Venue: Napier G03 Chair: Dr. Sook-Ying Ho Presenter: Manudha T. Herath
Performance analysis and optimisation of bend-twist coupled composite hydrofoils using fluid-structure interaction Manudha T. Herath* and Gangadhara B. Prusty School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: This paper presents the development of a shape-adaptive composite hydrofoil that utilises bend-twist coupled composite layups to enhance performance. The theory behind bend-twist coupling is presented and extended to the governing equations of bending for thin plates. Finite Element Analysis (FEA) technique is presented and validated to be used in both composites and Fluid-Structure Interaction (FSI) problems. An optimisation scheme for a composite propeller blade that reaps the benefits of bend-twist coupling is proposed. A validation of the proposed technique is presented using a simple bend-twist coupled composite plate.
Keywords: bend-twist coupling, fluid-structure interaction, laminate composites, optimisation.
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Session 17: Fluid-Structure Paper No: 122 Time: 1120 – 1140 Venue: Napier G03 Chair: Dr. Sook-Ying Ho Presenter: Amanullah Choudhry
Turbulent wake study of NREL phase VI wind turbine in a virtual wind tunnel using Large Eddy Simulation Amanullah Choudhry1*, Jang-Oh Mo1, Maziar Arjomandi1 and Young-Ho Lee4 1 School of Mechanical Engineering, University of Adelaide, South Australia 5005, Australia 4 Division of Mechanical and Energy-System Engineering, Korea Maritime University, Busan, 606-791, Korea *Corresponding author. Email: [email protected]
Abstract: The objective of the current investigation is to achieve a better understanding of the turbulent wake characteristics behind a wind turbine for the purpose of the improvement of the overall wind farm efficiency and a better prediction of the fatigue loads on tandem wind turbines. Large Eddy Simulation was performed at a low wind speed of 7m/s in a numerical wind tunnel model with dimensions similar to the NASA Ames Wind Tunnel (24.4 m x 36.6 m). An ANSYS CFD Fluent solver based on the dynamic Smagorinsky-Lilly model was employed to simulate the flow surrounding the wind turbine placed inside the numerical wind tunnel. For validation purposes, the aerodynamic characteristics of the blade were compared with the published experimental data of the NREL Phase VI. A good agreement was found between the experimental and the numerical results for the surface pressure distributions along the blade. It was observed that in the near-wake the turbulence intensity was a maximum of 12.12% at a distance of three rotor diameters downstream, after which a gradual decrease in the turbulence intensity was observed due to the wake instability. In the far-wake region, the turbulence intensity showed a tendency to increase, due to the presence of counter-rotating helical vortices determining the dynamics of far-wake. The system of vortices in the near-wake becomes unstable and breaks down due to the wake instability at a distance of approximately five rotor diameters downstream of the wind turbine. The vortex breakdown was used to define the boundary between the near and far-wake regions. The collapsed spiral wake was found to spread in all directions in the far-wake resulting in the formation of the two counter-rotating vortices which caused the gradual increase of turbulent intensity. The results and related discussion of the turbulent wake characteristics are presented in the current article.
Keywords: counter-rotating vortex pairs, large eddy simulation, turbulence intensity, vortex breakdown, wake instability, wind turbine.
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Session 17: Fluid-Structure Paper No: 011 Time: 1140 – 1200 Venue: Napier G03 Chair: Dr. Sook-Ying Ho Presenter: Yunpeng Xue
Experimental study of the flow structure in a vortex tube Yunpeng Xue*, Maziar Arjomandi and Richard Kelso*
School of Mechanical Engineering, the University of Adelaide, South Australia 5005, Australia *Corresponding author. Email: [email protected]
Abstract: With the single injection, a vortex tube generates cold and hot stream from two exits respectively, which was first found and investigated by Ranque. Different explanations for the temperature separation in a vortex tube have been proposed since the invention of the device. However, due to the difference and conflicts among those explanations, a clarification of the thermal separation is still required.
Understanding of the flow behaviour inside a vortex tube is an essential requirement in exploring the thermal separation. This paper reports on an experimental study in progress exploring the flow structure in a vortex tube. Flow properties in a vortex tube are measured and used to clarify the flow structure inside the tube. The velocity distributions along the tube are presented, which are different from previous studies. The transition from a forced vortex at the cold end to a free vortex near the hot end was first observed, which agrees with the author’s previous study[1]. The flow structures found in this research show positive supports for the proposed hypothesis of the temperature separation in the vortex tube.
Keywords: Ranque effect, Ranque-Hilsch vortex tube, temperature separation, vortex flow.
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Session 18: Rock Mechanics Paper No: 148 Time: 1020 – 1040 Venue: Napier G04 Chair: Prof. Arcady Dyskin Presenter: Aditya Khanna
Steady flow towards a row of collinear hydraulic fractures Aditya Khanna* and Andrei Kotousov School of Mechanical Engineering, The University of Adelaide, Australia *Corresponding author. Email: [email protected]
Abstract: Hydraulic fracturing is one of the most effective techniques for increasing the productivity of wells drilled in low permeability reservoirs and for alleviating near-wellbore formation damage. In the analysis of production schemes involving multiple fractured wells, the fracture is often assumed to be elliptical in shape or having a constant thickness. However, the shape of the hydraulic fracture can be more complicated and might significantly affect the productivity of the well system.
In this paper, a simple production scheme consisting of a row of fractured wells is considered. The flow is assumed to be steady state and the governing equation is written in terms of the fluid flux entering the fractures. The Gauss-Chebyshev quadrature method is used to obtain a numerical solution for the fluid flux distribution along the fracture. The effects of fracture conductivity, well interference and fracture shape are investigated. It has been found that over a certain range of governing parameters, the shape of the fracture significantly influences the productivity of well system. The results justify the importance of modelling the shape of fractures to simulate the flow in a system of wells using numerical solvers.
Keywords: hydraulic fracturing, collinear fractures, fracture shape, analytical model.
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Session 18: Rock Mechanics Paper No: 081 Time: 1040 – 1100 Venue: Napier G04 Chair: Prof. Arcady Dyskin Presenter: Luiz Bortolan Neto
On the residual opening of cracks with rough faces stimulated by shear slip Luiz Bortolan Neto* and Andrei Kotousov School of Mechanical Engineering, The University of Adelaide, Adelaide SA 5005, Australia *Corresponding author. Email: [email protected]
Abstract: The hydraulic stimulation of fractures has been widely employed worldwide for increasing the productivity of hydrocarbon reservoirs. Many exciting potential applications of this technique, specifically for geothermal reservoirs and coal seam gas (CSG) industries stipulate a strong need for new theoretical models and solutions capable to describe the residual fracture openings after hydraulic stimulations. In this paper a new mechanical model to predict the roughness induced fracture residual opening due to shear slip is developed. It is based on simplified and well established mechanical models of shear slip and contact law of rough surfaces. The solution procedure utilises the distributed dislocation technique, which reduces the governing system to a system of singular equations. The latter is solved using the standard Gauss-Chebyshev quadrature method.
Keywords: distributed dislocation technique, fracture mechanics, fracture residual opening, hydraulic fracturing, rock mechanics, roughness induced crack opening, slip opening, well stimulation.
120
Session 18: Rock Mechanics Paper No: 112 Time: 1100 – 1120 Venue: Napier G04 Chair: Prof. Arcady Dyskin Presenter: Mahinda D. Kuruppu
Development of a standard method for determining the plane strain fracture toughness of rock Mahinda D. Kuruppu1* and Takahiro Funatsu2 1 Western Australian School of Mines, Curtin University, Kalgoorlie 6433, Australia 2 Institute for Geo-Resources and Environment National Institute of Advanced Industrial Science and Technology (AIST), Central 7 1-1-1 Higashi, Tsukuba, Ibaraki, Japan 305-8567 *Corresponding author. Email: [email protected]
Abstract: A number of standard methods have been proposed to determine the Mode I plane strain fracture toughness of rock. The semi-circular bend (SCB) specimen has been widely used for fracture toughness determination of geomaterials owing to inherent favourable properties such as its simplicity, minimal requirement of machining and the convenience of testing. However, measurements of Mode I fracture toughness using SCB specimen have shown variability with specimen size. The minimum size requirements suggested by many theories are usually too large for practical applications. This research suggests an approximate, but relatively easily applied method, to satisfy the minimum size requirement. Fracture toughness of Kimachi sandstone was determined using the SCB specimen. By testing specimens of varying size, it was confirmed that the apparent fracture toughness increases with the specimen size. The trend line of the apparent fracture toughness displayed eventual stabilisation giving a value that can be considered as specimen size-corrected fracture toughness.
Keywords: brittle fracture, fracture mechanics, stress intensity factor, toughness testing.
121
Session 18: Rock Mechanics Paper No: 098 Time: 1120 – 1140 Venue: Napier G04 Chair: Prof. Arcady Dyskin Presenter: S.Saeid Hashemi
Effect of grain bonding on the stability of a borehole drilled through low cemented formations S.Saeid Hashemi*, Noune Melkoumian and Chaoshui Xu Deep Exploration technologies Cooperative Research Centre, School of Civil, Environmental and Mining Engineering, the University of Adelaide *Corresponding author. Email: [email protected]
Abstract: Achieving an in-depth understanding of the behaviour of low cemented formations such as running sands around a cylindrical borehole is of significant importance in identifying stability problems, designing adequate borehole supports and choosing an efficient drilling method. This paper presents numerical investigations on failure modes of unsupported vertical cylindrical boreholes drilled through weak formations, i.e. low cemented sands where the movement of individual grains is not restricted by sufficient cementation.
Distinct element method (DEM) was used for this study. The method enables to simulate sand grains and control normal and shear bonding between them. To simulate actual condition surrounding a borehole at a depth of 80m, a 2m x 2m x 2m cube made up of spherical particles with diameters ranging from 5mm to 70mm was constructed and analysed in the DEM code, PFC3D. The results showed that stress concentration developed in the ground due to the presence of a borehole leads to the formation of a damage zone around that borehole. When there is not sufficient bonding between the sand grains, the interaction between them results in their movement towards the borehole and the eventual collapse of the borehole wall. The effect of fluid flow on stability of boreholes has been studied as well.
The cementation between sand grains is mainly caused by the presence of clay particles in the formation. The bonding strength between sand grains is an intrinsic or micro property of the bonding material and is very difficult to measure in laboratory conditions.
The results obtained from current research will help to evaluate the effect of particle bonding on the mechanical behaviour of low cemented formations and develop methods to assess borehole stability during and after drilling through such formations.
Keywords: borehole stability, distinct element method, particle bonding, unconsolidated formations.
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Session 18: Rock Mechanics Paper No: 067 Time: 1140 – 1200 Venue: Napier G04 Chair: Prof. Arcady Dyskin Presenter: Liangchi Zhang
A method for estimating the fracture toughness of rocks Qingyu Yao, Haihui Ruan and Liangchi Zhang* School of Mechanical and Manufacturing Engineering, the University of New South Wales, NSW, 2052, Australia *Corresponding author. Email: [email protected]
Abstract: A fast measurement of the fracture toughness of rocks is very much required by the mining and geological industry. This paper proposes a simple rock chipping method to determine the fracture toughness of rocks using a simple experimental setup. The chipping was conducted by indenting a rock piece at a spot near its edge using a sharp indenter. The shape of the rock sample is not important provided that the chipping edge is approximately straight, and that the indenting and chipping surfaces are roughly planar and perpendicular to each other. A series of chipping tests were carried out on four kinds of sandstones, the Bauhaus, Littlewood, Appin and Pyrmont produced in New South Wales of Australia. A 30kN load cell mounted on a universal Instron machine was used to perform the indentation. Pyramidal and conical indenters were used to understand the geometry effect of the indenters on the fracture behaviour of the rocks.
Keywords: rock, indenting distance, peak force, toughness.
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Session 19: Solid Mechanics II Paper No: 070 Time: 1020 – 1040 Venue: Napier 102 Chair: Dr Stuart Wildy Presenter: Christopher Thang
Development of a rapid drop test for surface quality inspection Christopher Y. Thang1 and Chin K. Liew1,2* 1 School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Australia 2 Cooperative Research Centre for Advanced Composite Structures, 50 Schneider Road, Eagle Farm, Brisbane,
Australia *Corresponding author. Email: [email protected]
Abstract: In material bonding, the surface energy of the adherend can be an excellent predictor of adhesive bond strength. In this research, the use of the sessile drop test as a pre-bond inspection tool for bonded composite repairs was investigated. A portable goniometer suitable for a maintenance workshop in the aviation industry was designed and built. Dimethyl sulfoxide and water were used as testing fluids, dispensed in 3 μl quantities. Contact angles were measured using the spherical approximation for a range of surfaces which included samples that had been peel-plied, hand sanded, grit blasted and contaminated with silicone release agent. The surface energies of the samples were then evaluated using the Owens-Wendt and Girifalco-Good-Fowkes-Young (GGFY) methods. Although the GGFY method successfully distinguished contamination, difficulties arose when evaluating surface roughness. Peel-ply surfaces also had varying contact angles due to irregular droplet shapes. The Owens-Wendt method was also found to be inaccurate with only two test fluids although this is regarded as industry standard, It is for these reasons that traditional surface energy methods were considered impractical for a workshop environment. An alternate measurement parameter considered was the droplet diameter where the same testing fluids were imaged from the top instead. This measurement successfully differentiated contamination and also allowed the abrasion process to be determined. In addition, the degree of abrasion could be determined between grit blasted and untreated peel-ply surfaces. This test was found to be more accurate than the traditional surface energy techniques and has the potential to form part of a pre-bond surface certification process for bonded composite repairs.
Keywords: composite adhesive bonding, pre-bond inspection, quality assurance, surface testing, surface energy.
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Session 19: Solid Mechanics II Paper No: 079 Time: 1040 - 1100 Venue: Napier 102 Chair: Dr Stuart Wildy Presenter: Muhammad A. Ashraf
A numerical study of the impact properties of sandwich panels with different cores Karthik Ram Ramakrishnan1,2, Krishna Shankar1*, Philippe Viot2 and Sandra Guerard2 1 School of Engineering and Information Technology, Australian Defence Force Academy, University of New South Wales, Canberra, Australia 2 Arts et Metiers ParisTech, I2M-DuMAS UMR 5295, F-33400 Talence, France *Corresponding author. Email: [email protected]
Abstract: Sandwich structures based on strong, stiff skins bonded to either side of a low density core material are finding increasing use in aerospace, offshore and marine industries. The skins are designed to resist tensile and compressive stresses and are usually made of aluminium or fibre reinforced polymers. The core is designed to resist shear stresses and is usually made of balsa wood, polymer foams, or expanded metal or polymer honeycombs. Unfortunately, some sandwich structures have very low energy absorption capability when subjected to impulsive loads normal to the sandwich plane. This is of concern due to the susceptibility of sandwich structures to damage caused by foreign object impact. Since the damage behavior of sandwich structures are affected by the mechanical properties of both core and laminated facesheets, the damage behaviors under impact loading deserve careful investigation to ensure the reliability and safety of sandwich structures. The purpose of this paper is to compare the mechanical response of sandwich panels with different cores subjected to impact loading. An approach for modelling sandwich structures in the commercial finite element code LS-DYNA is presented. The core is modelled with solid elements and shell elements are used for the thin facesheets. Sandwich panels with glass fibre-reinforced polymer facesheets were used, combined with two different cores; polystyrene foam and polypropylene honeycomb. A parametric study can be done using the FE model presented in this paper that would provide valuable information to help select appropriate core material for maximum impact resistance.
Keywords: finite element, is-dyna, numerical modelling, sandwich structures.
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Session 19: Solid Mechanics II Paper No: 089 Time: 1100 – 1120 Venue: Napier 102 Chair: Dr Stuart Wildy Presenter: Timothy Paul Hutchinson
Testing in order to measure the protection against impact of people, manufactured items, and agricultural produce: How to consider all severities of shock Timothy P. Hutchinson*, Robert W. G. Anderson and Daniel J. Searson Centre for Automotive Safety Research, University of Adelaide, South Australia 5005 *Corresponding author. Email: [email protected]
Abstract: Instrumented headforms are projected at cars to check that the vehicle is not overly injurious if a pedestrian is struck. We argue that there are at least two different aspects to performance: the impact severity in the test conditions (measured by HIC, the Head Injury Criterion), and the speed at which bottoming out occurs (this refers to the vehicle surface deforming sufficiently that the much more rigid structures underneath are contacted). It is desired to know performance over the wide range of real-life impact conditions, yet the number of tests to be conducted is limited. A procedure is proposed that estimates performance averaged over different speeds (and perhaps also averaged over effective head mass). There are three components: (a) an equation for the dependence of HIC on speed (and perhaps mass), which includes the effect of bottoming out as a sharp rise in severity beyond a certain level of impact energy, (b) an equation for how bad are different levels of HIC (the probability of some specific outcome, such as death or skull fracture, is likely to be used here), and (c) the probability distribution of impact speed (and perhaps mass). Other safety tests (such as impact testing of helmets) are plainly analogous, and similar considerations apply in the packaging and handling of manufactured items and agricultural produce: cushioning should be soft enough not to cause damage itself yet stiff enough to prevent bottoming out.
Keywords: average severity, cushioning, impact testing, pedestrian subsystem testing, speed of impact.
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Session 19: Solid Mechanics II Paper No: 077 Time: 1120 – 1140 Venue: Napier 102 Chair: Dr Stuart Wildy Presenter: Anthony Sexton
Experimental characterisation of the formability of a thermoplastic fibre metal laminate Anthony Sexton1*, Wesley Cantwell2, Matthew Doolan1 and Shankar Kalyanasundaram1 1 Research School of Engineering, Australian National University, Canberra 2 School of Engineering, University of Liverpool, Liverpool *Corresponding author. Email: [email protected]
Abstract: This study aims to assess the forming behaviour of thermoplastic fibre metal laminates based on a self-reinforced polypropylene composite and an aluminium alloy. The development of a method for the rapid manufacturing of parts made from fibre metal laminates would facilitate the widespread adoption of these materials in the automotive and renewable energy industries. Metallic parts are most commonly manufactured using the method of stamp forming and research into the application of this method to materials such as fibre metal laminates is gathering interest. In this investigation, specimens of varying geometry were stretched over a hemispherical punch and a non-contact optical measurement system was used to detail the stretch forming and analyse the effect of deformation mode on the formability of the laminate. The results from the experimentation were used to determine a forming limit diagram for the fibre metal laminate and to identify the safe forming limits of the material. In addition, the evolution of strain at two points of interest was observed to determine the deformation mode in each specimen and to determine the state of strain in the region of failure. These results were then compared with the forming of monolithic aluminium specimens. A significant finding of this work was that the FML showed superior formability than aluminium. This was shown primarily through the increased forming window elucidated by the forming limit curve for the FML and the more uniform meridian major strain distribution in the FML compared to the aluminium.
Keywords: composite, fibre metal laminate, formability, optical strain measurement, stretch forming.
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Session 19: Solid Mechanics II Paper No: 183 Time: 1140 – 1200 Venue: Napier 102 Chair: Dr. Sabrina Vantadori Presenter: Andrew Dixon
Strip buckling from side-guard contact during strip rolling Andrew Dixon and Daniel W.Y. Yuen* Bluescope Steel Research, Port Kembla, NSW *Corresponding author. Email: [email protected]
Abstract: To obtain the desired steel strip thickness, hot slabs are rolled successively through a tandem mill of rolling stands. Before a rolling stand, side-guards are used to ensure the strip enters the stand at the correct lateral position and angle. Occasionally if there is excessive lateral off-centre of the strip, the strip edge will buckle and turn-over upon contact with the side-guard, resulting in a “cobble” at the next rolling stand where the buckle is “rolled-in”. Conditions necessary for lateral buckling of the strip upon contact with the side-guard are mathematically investigated. Under a small lateral off-centre, the strip will bend laterally while at larger degrees of lateral off-centre, and corresponding higher side-guard forces, the strip edges are predicted to buckle vertical to the plane of the strip. It is proposed that for a strip buckle to be “rolled-in” the buckle curvature must be sufficiently large to form of a plastic “hinge”. The conditions for a the formation of a “hinge” are predicted by modelling the lateral buckle using combined Elastica/Plastica equations. It is shown the hinge will only occur if there is sufficient friction between the strip and the side-guard, the strip contacts the side-guard at a short distance from the upstream rolling stand and/or the strip is sufficiently thin and wide.
Keywords: buckling, elastica, plastica, plastic hinge, side-guard, strip rolling.
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Session 20: Composites III Paper No: 061 Time: 1350 – 1410 Venue: Napier G03 Chair: Prof. Yuris Dzenis Presenter: Sebastian Davey
Effect of preheat temperature on the formability of carbon fibre/PEEK composites Sebastian Davey1*, Raj Das2, Wesley Cantwell3 and Shankar Kalyanasundaram1
1 Research School of Engineering, Australian National University, Canberra, Australia 2 Department of Mechanical Engineering and Centre for Advanced Composite Materials, University of Auckland, New Zealand 3 Centre for Materials and Structures, University of Liverpool, United Kingdom *Corresponding author. Email: [email protected]
Abstract: Thermoplastic composites are currently utilised in applications where high specific stiffness and strength is required. However, current manufacturing processes are time consuming and costly. For these materials to be utilised in a wide range of applications, rapid forming mechanisms must be developed. In this study, the formability of carbon fibre reinforced PEEK was examined in stamp forming processes. Composite blanks created from plain weave carbon fabric in a PEEK matrix were formed until failure at various temperatures in an open-die system using a hemispherical punch. Monolithic aluminium samples were formed for the sake of comparison. During forming, real-time strain measurements were taken from the lower surface of the blanks and strain distributions were plotted. Results showed that CF/PEEK experiences a much lower maximum strain than aluminium at any given depth, allowing it to form without inducing failure in the carbon fibres. High temperatures were found to cause large shear strains. This caused a slight reduction in maximum strain in the fibre direction of the composite, slightly increasing the forming depth. A complete understanding of the forming behaviour of CF/PEEK could enable rapid forming processes to be implemented, thereby allowing this material to be utilised in a wide variety of applications.
Keywords: carbon fibre reinforced polymers, real-time strain measurements, stamp forming, thermoplastic composites.
129
Session 20: Composites III Paper No: 140 Time: 1350 – 1410 Venue: Napier G03 Chair: Prof. Yuris Dzenis Presenter: Monis Kazmi
Exploring the potential for Vacuum Assisted Oven Consolidation (VAOC) of Natural Fibre Reinforced Thermoplastic Sheets (NFRTS) Syed Monis R. Kazmi, Raj Das*, Krishnan Jayaraman, and Simon Bickerton Centre for Advanced Composite Materials, Department of Mechanical Engineering, University of Auckland, New Zealand *Corresponding author. Email: [email protected]
Abstract: Fibre reinforced plastics are being increasingly used in automotive, aerospace, marine, sporting and domestic industries. Considerable research has been carried out on natural fibres as reinforcements. They are obtained from renewable resources, possess higher stiffness per unit mass compared to glass fibres and are biodegradable. Significant opportunities exist in the industry to make the manufacturing of complex shaped (e.g. including. single or double curvature) composite parts more efficient using natural fibre reinforced thermoplastics with industrially accepted thermo-mechanical properties. Part geometry, size, processing time and scale of production are the key factors affecting tooling costs. This paper extends our previous work on vacuum assisted oven consolidation (VAOC) of natural fibre reinforced thermoplastic sheets (NFRTS). It involves comparisons of the manufacturing cycles and reinforcements used so far. In this work flax fibre reinforcement was selected because of its superior impact resistance, tensile strength, stiffness and low density as compared to other natural fibres. The main thermoplastic matrix used was polypropylene due to its availability as sheets, lower melting point and a higher melt flow rate compared to other thermoplastics. Three flax reinforcements, unidirectional (310 g/m2), fine twill (330 g/m2) and coarse twill (565 g/m2), were used. The compaction behaviour of each reinforcement was investigated and used to target a range of achievable fibre volume fractions for the panel manufacture. An experimental setup was designed to measure the relevant processing parameters during the experiment. Air pressure inside the composite, temperature of both the composite and the oven atmosphere, and thickness of the composite during the experiment were measured. The mould temperature inside the oven was first increased to the melting temperature of the thermoplastic, held at that temperature for certain time periods and then cooled subsequently. The holding time was varied to study its effect on consolidation quality. Microscopy, tensile and short beam shear tests were performed to assess structural integrity, strength and stiffness of the composite. Thickness of the manufactured parts was measured to calculate the achieved fibre volume fraction. This paper explores the potential of VAOC of NFRTS in order to reduce manufacturing time without any significant degradation in mechanical properties. It was found that the mechanical properties of NFRTS do not change appreciably even after modifying the process to reduce the manufacturing time.
Keywords: Vacuum compaction, oven processing, sheet consolidation, natural fibre, thermoplastics, permeability.
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Session 20: Composites III Paper No: 116 Time: 1430 – 1450 Venue: Napier G03 Chair: Prof. Yuris Dzenis Presenter: Hitoshi Takagi
Development and performance of all bamboo-based green composites Hitoshi Takagi1*, Antonio N. Nakagaito1, Kyohei Yokota2, and Goshi Takeichi3 1 Institute of Technology and Science, The University of Tokushima, Tokushima, Japan 2 Department of Mechanical Engineering, The University of Tokushima, Japan 3 Graduate School of Advanced Technology and Science, The University of Tokushima, Japan *Corresponding author. Email: [email protected]
Abstract: In this paper, we attempted to fabricate binderless green composites using bamboo fibre and bamboo powder as matrix. The influence of moulding conditions on their tensile behaviour was investigated by changing the moulding temperature and pressure. Except for the composites moulded at low temperature range from 100°C to 120°C, their tensile strength decreased with increasing the moulding temperature. When the moulding time increased, their tensile strength decreased. Average tensile strength of the all bamboo-based green composite moulded at 120°C and 10 MPa for 10 min was 170 MPa. The decreases in tensile strength of all bamboo-based green composites moulded at temperatures higher than 120°C may be responsible for the strength drop of the reinforcing bamboo fibre derived from thermal decomposition. In order to obtain detailed information about the adhesion behaviour of bamboo powder and bamboo fibre, photomicrographs were taken of the fracture surfaces of the composites. The results show that moulding condition, especially moulding temperature, has a great effect on the mechanical properties of bamboo fibre reinforced all bamboo-based green composites.
Keywords: bamboo, binderless composites, green composites, steam-explosion, tensile properties.
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Session 20: Composites III Paper No: 039 Time: 1450 – 1510 Venue: Napier G03 Chair: Prof. Chun Wang Presenter: Salah Shalouf
Structural composites embedded with lithium polymer batteries Salah M. Shalouf, Jin Zhang and Chun H. Wang*
Sir Lawrence Wackett Aerospace Research Centre, School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne, VIC 3083, Australia *Corresponding author. Email: [email protected]
Abstract: Structural battery composites that concurrently carry load and store electric energy will transform future vehicles. They can replace inert structural components and simultaneously provide supplementary power for light load applications. Rechargeable lithium polymer battery cells are embedded into carbon fibre/epoxy matrix composite laminates, which are then tested under tension and three-point bending to investigate the mechanical and electrical performances of structural batteries. The experimental results show that the integration of battery cells into composite laminates has negligible impact on the mechanical strengths of the composite structures. Furthermore, the battery cells remain 95% effective at loads up to about 60% of the ultimate flexural failure load and 50% of the ultimate tensile failure load.
Keywords: energy storage, multifunctional composites, structural battery, unmanned vehicle, lithium ion battery.
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Session 21: Computational Mechanics Paper No: 078 Time: 1350 – 1410 Venue: Napier G04 Chair: Prof. Filippo Berto Presenter: Anthony Sexton
Finite element simulation of the stretch forming of annealed aluminium sheets Anthony Sexton1*, Sebastian Davey1, Wesley Cantwell2, Matthew Doolan1 and Shankar Kalyanasundaram1 1 Research School of Engineering, Australian National University, Canberra 2 School of Engineering, University of Liverpool, Liverpool *Corresponding author. Email: [email protected]
Abstract: The formability of a material is an important consideration in the design of manufacturing processes for that material. Finite Element Analysis (FEA) allows for the relatively rapid and inexpensive determination of material formability and reduces the number of experiments needed to be performed. The validation of a finite element model against established forming experiments, which cover all deformation modes, allows the modelling of more complex components. In this study, aluminium is used to provide a point of reference for the simulation of material forming. Aluminium is one of the candidate materials considered for reducing the weight of automobiles. Experimental specimens were tested and an open die configuration was used in order to facilitate measurement of the surface strain using the ARAMIS three-dimensional strain measuring system. The forming of these experimental aluminium specimens that were stretched over a hemispherical punch was then simulated using ABAQUS/Standard. In order to develop a complete model of the forming behaviour, specimens of varying geometry were assessed to obtain deformation behaviour in the aluminium ranging from uniaxial tension to biaxial stretch. The evolution of strain throughout the forming process was analysed and compared to finite element simulations. The forming limit diagram and the surface strain contours were also compared to the finite element model. Excellent agreement was found between the experimental results and the FEA. This demonstrates that complex components that experience a combination of deformation modes can be simulated using FEA.
Keywords: aluminium, finite element analysis, formability, forming limit curve.
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Session 21: Computational Mechanics Paper No: 119 Time: 1410 – 1430 Venue: Napier G04 Chair: Prof. Filippo Berto Presenter: Dan Dobrotă
Methods for determining rubber and composite materials with rubber matrix breaking resistance Dan Dobrotă1 and Gheorghe Amza2* 1 University “Constantin Brâncuşi” of Târgu-Jiu, Romania 2 University Polytechnic of Bucharest, Romania *Corresponding author. Email: [email protected]
Abstract: Knowing break resistance for different products made of rubber or other composite materials with rubber matrix is very important to determine their behavior in exploitation as well as for the situation when their recycling is necessary. Because rubber is an elastic material, with non-linear behaviour, in case of traction application, the starting point to establish mathematical modeling was the function of deformation energy or the W elastic potential, which represents the modification of Helmotz free energy of the material to deformation. The mathematical modeling of the composite materials with rubber matrix was based on the properties that reinforcement materials and rubber matrix have. The experimental research was realized for different types of rubber, and for composite materials with rubber matrix it was made on specimens from conveyor belts reinforces with textile insertions. Also, in order to verify the proper characteristic of the established mathematical models was made a non-linear analysis through the finite elements method. Correct mathematical models determination are important especially due to quick information that they offer concerning that materials traction behaviour, without being necessary a supplementary experimental research. Values established for traction break resistance through the agency of the mathematical models as well as the ones obtained by modeling through finite elements method and the experimental researches, led to very close values, which proves the accuracy of the mathematical models but also the fact that the method of the finite elements can also be used in the design stage.
Keywords: calculation patterns, composite materials, experimental analysis, finite elements analysis, rubber.
134
Session 21: Computational Mechanics Paper No: 058 Time: 1430 – 1450 Venue: Napier G04 Chair: Prof. Filippo Berto Presenter: Huayi Peng
The modification of finite element model of a coupled slab system utilizing measured modal parameters Hua Y. Peng* and Heung F. Lam
Department of Civil and Architectural Engineering, City University of Hong Kong, HKSAR, China *Corresponding author. Email: [email protected]
Abstract: This paper focuses on the modification of a finite element modeling of the coupled slab system of the Tin Shui Wai Indoor Recreation Centre in Hong Kong utilizing a set of measured modal parameters obtained from the field tests. The modification includes not only the updating of the model parameters through an optimization algorithm, but also the correction of the class of models based on the observed discrepancies between the model-predicted and measured modes shapes.
The slabs for floors 2 and 3 of the Recreation Centre are supported by two truss systems, which are connected through six inner steel columns with diagonal braces. As a result, the vibrations of the two slabs are coupled. The 3D finite element (FE) model of the two coupled truss systems together with the two slabs was established referring to the design drawings. In order to fully determine the dynamic properties of the coupled slab system, a series of full-scale ambient and forced vibration tests were carried out to measure the vibration of the coupled slabs at 126 measurement stations. Translational vibration along three directions (denoted as x, y and z) is measured at each station resulting in, 378 (= 126 3) measured degrees of freedom (DOFs).
The paper reports not only the finite element modeling of the structure but more importantly the step-by-step correction of the class of models in order to obtain a representative model class to capture the vibration characteristics of the real structure. Besides, this paper also presents the structural model updating in fine-tuning the model parameters utilizing the measured modal parameters (i.e., the natural frequencies and modes shapes). Modal Assurance Criteria (MAC) was adopted for solving the modes pairing problem before model updating was conducted. This paper provides valuable information and important experience in the practical applications of structural model updating techniques in the finite element modeling of real structural systems.
Keywords: ambient vibration, coupled slabs, class of models, MAC, model modification, 3D FE model.
135
Session 21: Computational Mechanics Paper No: 182 Time: 1450 – 1510 Venue: Napier G04 Chair: Prof. Filippo Berto Presenter: Mohammad Khan
A new approach to the investigation of mixed lubrication in metal strip rolling Mohammad N. Khan1, Haihui Ruan1, Liangchi Zhang1*, Xianming Zhao2 and Xiaoming Zhang2 1School of Mechanical and Manufacturing Engineering, The University of New South Wales, NSW 2052, Australia 2 State Key Laboratory for Rolling Technology, Northeastern University, Shenyang, Liaoning, 110004, China *Corresponding author. Email: [email protected]
Abstract: Mixed lubrication is an important lubrication mode, and if controlled properly, can improve the performance of metal rolling. However, understanding the mechanisms of mixed lubrication is still a big challenge in the discipline because of the complexity caused by the fluid-solid interaction and random surface asperity deformation in a rolling process. A complete solution to mixed lubrication with full resolution down to the microscopic asperity level is formidable although the fundamental fluid and solid mechanics have been established. A practical approach is to solve the problem in the framework of continuum mechanics with the ingredients of microscopic asperity contacts and the lubricant flow at the interface. This paper aims to take such challenge by establishing an integral approach to reveal the mechanisms of the mixed lubrication in metal strip rolling. This new approach analyses the overall strip deformation with explicit finite element method, but introduces an equivalent interfacial layer to capture the microscopic interface mechanics including the random asperity deformation using a statistical formulation and the effect of lubricant using the modified Reynolds equation. It was found that this approach can effectively predict the contact pressure, shear traction and friction in metal strip rolling processes.
Keywords: fluid-solid interaction, friction, mixed lubrication, random asperity deformation, rolling, shear, statistical modelling.
136
Session 22: Optimization / System Identification Paper No: 113 Time: 1350 – 1410 Venue: Napier 102 Chair: A/Prof. Michael Sek Presenter: Zhen Luo
Topology optimization of lightweight structures using a meshless Shepard function approximant Zhen Luo*, Yu Wang and Nong Zhang School of Mechanical and Mechatronic Engineering, University of Technology, Sydney, NSW 2007 *Corresponding author. Email: [email protected]
Abstract: This paper aims to propose a new structural topology optimization method using a Shepard function approximant and meshless Galerkin weak-forms, totally based on a set of arbitrarily scattered field nodes in the design domain. The moving least square (MLS) is applied to construct the meshless shape functions, in which the meshless shape function with the zero-order consistency will degenerate to a specific family of functions: “Shepard function”, while the shape function with the first-order consistency refers to the widely studied “MLS shape function”. The Shepard function is utilized to develop a physically meaningful dual-level density approximant due to its non-negative and range-restricted properties. First, the Shepard function is included into the problem formulation to construct a nodal density-based non-local approximant with enhanced smoothness in terms of the original set of nodal density variables. So the density at any node can be evaluated according to the densities inside the influence domain of the current node. Second, in numerical implementation, the Shepard method with a singular weight function is employed to develop a point-wise density interpolant, in which the density at any computational point is determined by the surrounding nodal density variables within the influence domain of the concerned computational point. As a result, both the topology and the field quantities can be described via the dual-level point-wise density approximation scheme, just in terms of a set of generic design variables scattered at field nodes. MLS shape function is used to implement the meshless approximations of the system equations, while the Lagrangian multiplier method is included to enforce the essential boundary conditions due to the lack of Kronecker delta function property of the MLS shape function. Two numerical examples are applied to demonstrate the effectiveness of the proposed method, in particular its applicability in avoiding numerical instabilities.
Keywords: Topology optimization, meshless Galerkin methods, shape function, density approximant, numerical instabilities.
137
Session 22: Optimization / System Identification Paper No: 006 Time: 1410 – 1430 Venue: Napier 102 Chair: A/Prof. Michael Sek Presenter: Jendi Kepple
A new multi-objective robust optimisation methodology Jendi I. Kepple1*, Gangadhara B. Prusty1, Garth M.K. Pearce1, Donald W. Kelly1 and Rodney S. Thomson2,3 1 School of Mechanical and Manufacturing Engineering, University of New South Wales (UNSW), Sydney, NSW
2052, Australia. 2 Advanced Composite Structures Australia, 4/11 Sabre Drive, Port Melbourne, VIC 3207, Australia. 3 Cooperative Research Centre for Advanced Composite Structures (CRC-ACS), Melbourne, VIC 3207, Australia. *Corresponding author. Email: [email protected]
Abstract: An improved approach to a robust indexing method that will be useful for designing weight-constrained aerospace structures is presented in this paper. A brief review of current stochastic analysis and robust design methods and their applications are outlined. In particular, Monte-Carlo generated stochastic analysis and a robust indexing method which provide designers with formulas that quantify the “robustness” of such structures are reviewed. The robust indexing method is improved to account for the needs of structural designs with multiple constraints. In designing for aerospace structures, the two main objectives are to maximise the robustness and minimise the weight of the structure. The improved indexing method is capable of evaluating both aspects and quantitatively ranks the different designs. The best performing designs are given higher values. The proposed method is validated through application to the design of cylinders with multiple constraints subject to axial loads which are representative of launch vehicle airframes. Analytical calculations and finite element (FE) simulations were utilised to define the optimum and most robust design.
Keywords: engineering structures, robust design, robust optimisation, stochastic analysis.
138
Session 22: Optimization / System Identification Paper No: 219 Time: 1430 – 1450 Venue: Napier 102 Chair: A/Prof. Michael Sek Presenter: Mohsen Askari
Application of extended, unscented, iterated extended and iterated unscented Kalman Filter for real-time structural identification Mohsen Askari*, Jianchun Li and Bijan Samali
School of Civil and Environmental Engineering, University of Technology Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: System identification refers to any systematic way of deriving or improving models of dynamical systems through the use of experimental and field testing input–output data. In the field of civil engineering, identification of the state of a structure during service condition under dynamic loading, such as earthquake, in order to detect any damage as it occurs, has posed a great challenge to the research community. Therefore, online and real-time structural identification has attracted a great deal of attentions in the structural engineering research over the past decades, especially when input-output measurement data are contaminated by high-level noise. Among real-time identification methods, one of the most successful and widely used methods for estimation of states and parameters is the Kalman filter and its various nonlinear extensions like Extended Kalman Filter (EKF) and iterated Extended Kalman Filter (IEKF). However, these methods are not effective in the case of highly nonlinear problems. To overcome the problem, two filtering techniques, namely unscented Kalman filter (UKF) and iterated unscented Kalman filter (IUKF), have been recently developed to handle any functional nonlinearity.
In this paper, an investigation has been carried out on the aforementioned methods for their effectiveness and efficiencies through a highly nonlinear SDOF structure as well as a two-storey linear structure. Results show that, although IEKF is an improved version of EKF, the IUKF, in most of cases, produces better results on state estimation and parameter identification than UKF and IEKF. IUKF is also more robust to measurement noise levels compared to the other approaches.
Keywords: online system identification, real-time structural identification, extended Kalman filter, iterated extended Kalman filter, unscented Kalman filter, iterated unscented Kalman filter.
139
Session 22: Optimization / System Identification Paper No: 220 Time: 1450 – 1510 Venue: Napier 102 Chair: A/Prof. Michael Sek Presenter: Mohsen Askari
Adaptive multiple forgetting factor recursive least square (AMFF-RLS) for real-time structural identification with unknown input Mohsen Askari*, Jianchun Li and Bijan Samali School of Civil and Environmental Engineering, University of Technology Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: System identification refers to any systematic way of deriving or improving models of systems through the use of experimental and field testing input–output data. In the field of civil engineering, identification of the state of the structure during the dynamic loads, such as earthquake, to predict the current state of the structure and detect any damage or hazard, when it occurs, has posed a great challenge to the research community. Therefore, online and real-time structural parameters identification has recently drawn more attractions, although few research works have been reported especially for cases where measurement data are contaminated by high-level noise and some of the excitations are unknown. The Recursive Least Square with single forgetting factor has been widely used in estimation and tracking of time-varying parameters in the fields of electrical and mechanical engineering. However, when there are multiple parameters that each (or some) varies with a different rate, this method cannot perform well. On the other hand, a priori information on the changing rate of the parameters might not be available, and the forgetting factors must be updated adaptively. This paper presents a new adaptive tracking technique, based on the Recursive Least Square (RLS) approach with Adaptive Multiple Forgetting Factors (AMFF). The proposed method considers an adaptive rule for each of the forgetting factors assigned to each of the parameters and thus, enables simultaneous estimation of the time-varying stiffness and damping of the storeys of the structure. Numerical examples show that results of this RLS-based approach are accurate and robust, in identification of the unknown parameters such as damping, stiffness and unknown excitations, even when the observed data are contaminated with different types and significant levels of noise.
Keywords: structural health monitoring, online system identification, damage detection, recursive least square, adaptive forgetting factor.
140
Session 23: Dynamics III Paper No: 025 Time: 1540 – 1600 Venue: Napier G03 Chair: A/Prof Ian Howard Presenter: David Eager
Characterisation of trampoline bounce using acceleration David Eager*, Chris Chapman and Kenneth Bondoc Faculty of Engineering and Information Technology, University of Technology Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: The hazards associated with trampoline usage have been extensively researched in biomechanics and within the product safety and injury prevention community. To-date little research has been published on the biomechanical benefits associated with trampoline usage. The primary aim of this research project was to measure the cyclical G-force loading experienced by a trampoline user under varying conditions. The experimental apparatus incorporated a tri-axial accelerometer system coupled with a high-speed camera to measure the trampoline bed deflection with respect to time. Three commonly available trampolines were studied. The acceleration and trampoline bed displacement data were measured simultaneously when triggered by the movement of the trampoline user. The variables studied included: the slope of the leading-edge of the acceleration pulse, the slope of trailing-edge of the acceleration pulse, the peak acceleration, the peak to peak cycle-time, air-time, and the bed deflection. Trampoline users experience cyclical loadings between almost weightlessness to approximately 5 G-force. Both qualitative and quantitative data was used to characterise the performance of each trampoline. The quantitative data were tested by enlisting volunteers to duplicate the experimental conditions and then provide their subjective opinions on the performance of each trampoline through the completion of a survey questionnaire.
Keywords: acceleration, biomechanics, bounce, cardiovascular exercise, cyclical G-force, health benefits, trampoline.
141
Session 23: Dynamics III Paper No: 222 Time: 1600 – 1620 Venue: Napier G03 Chair: A/Prof Ian Howard Presenter: Michael A. Sek
On chaotic interaction between product and cushioning during random vibration testing of protective packaging for transportation Michael A. Sek School of Engineering and Science, Victoria University, Melbourne, Australia Email: [email protected]
Abstract: Products need to be protected against risks of transportation environment, which include mechanical hazards such as shocks and vibration. Typically, it is accomplished by incorporating a form of cushioning. Unfortunately, most of materials used for this purpose are not environmentally friendly and optimisation of the system in order to reduce the use of materials is important. Transportation packaging is being subjected to various laboratory tests that attempt to simulate the hazards of transportation environment, such as vehicle vibrations, and their effect on the critical component within transported products. Random vibration tests utilising various Power Spectral Density (PSD) profiles are common and a number of PSDs are recommended by organisations such as the ASTM or ISTA (International Safe Transit Association). These tests are often time-compressed whereby test duration is reduced and compensated for by increasing the test level of vibrations, however conclusions relating to successful damage replication are ambiguous.
The paper deals with a rudimentary product-cushion system, comprising a cushion made of polyethylene foam supporting a product and subjected to the static stress optimised for shock protection. The system was exposed to random vibrations described by a PSD of the same shape and nine different RMS levels from 0.1G to 0.5G, selected to induce instantaneous excitation either below or exceeding ±1G. The effect of excitation level on system vibration transmissibility, the relative to excitation vibration response spectra of hypothetical critical elements and their actual responses were investigated. Using experimental data supported by numerical simulation it is demonstrated in the paper that, when the excitation level produced by the shaker reaches certain threshold, a product-cushion system, in addition to being nonlinear, cannot be treated as time-invariant. As the result, dynamics of the system and the cause-effect relationship become chaotic. It is shown that a paradoxical phenomenon can develop as an outcome of this chaotic behaviour. As vibration excitation levels increase, some critical elements may in fact decrease their level of vibration. In this case, for some critical elements a reduction of mean power of response vibration by 40% with the increase of mean power of excitation by 225% was detected. This paradox may explain inconclusive outcomes of some simulated transportation vibration tests involving time-compression.
Keywords: chaotic behaviour, environmental shocks and vibration, nonlinear, time variant system, vibration response spectrum.
142
Session 23: Dynamics III Paper No: 115 Time: 1620 – 1640 Venue: Napier G03 Chair: A/Prof Ian Howard Presenter: Arcady Dyskin
Vertical vibrations and detachments of drill bits in rotary drilling Arcady V. Dyskin1*, Elena Pasternak2 and Igor Shufrin1,2 1 Deep Exploration Technologies Cooperative Research Centre, School of Civil and Resource Engineering, University of Western Australia, Australia 2 Deep Exploration Technologies Cooperative Research Centre, School of Mechanical and Chemical Engineering, University of Western Australia, Australia *Corresponding author. Email: [email protected]
Abstract: This study deals with vertical vibrations (chatter) in the deep rotary drilling. The vertical vibrations play negative role in this type of drilling, since they cause detachment of a drill bit from the rock and subsequent impacts (bit-bounce), thus decreasing the cutting efficiency and producing additional wear on the drill bit. The main mechanism of this chatter is a bilinear stiffness of the drilling system due to low stiffness of the long drill string and comparatively high stiffness of the rock. In this study, we assume the rock as infinitely rigid and model the system as an impact oscillator. This oscillator is excited by the vertical momentum created by the rock asperities encountered by the rotating drill bit in the process of drilling. The oscillations are governed by the combined mass of the drill bit, the collar, the mud trapped there as well as the rotational speed, the viscosity of the mud and the fraction of the energy consumed in rock fragmentation. We demonstrate that the high rotational speeds lead to the vertical chatter and discuss ways to suppress these oscillations.
Keywords: impact oscillator, coefficient of restitution, impact velocity, damping, mud viscosity.
143
Session 23: Dynamics III Paper No: 214 Time: 1640 – 1700 Venue: Napier G03 Chair: A/Prof Ian Howard Presenter: Nik Abdullah Nik Mohamed
Dynamic analysis of beam with multiple cracks using Transfer Matrix Method Nik Abdullah Nik Mohamed*, Sallehuddin M. Haris, Reza Alebrahim, Shakib Sharifian and Salvinder Singh Karam Singh Department of Mechanical and Material Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia *Corresponding author. Email: [email protected]
Abstract: This paper studies the effect of vibration on the existing cracks in beams due to mass loading. Vibration analysis of cracked beam is one of the subjects which have attracted the attention of many researchers in this area. There are many researches that have considered crack in the beam but there are limited studies done on the beam with multiple cracks. The existence of crack in the beam cause decreasing natural frequencies which by increasing number of cracks more reduction are done. Unexpected decrease in natural frequencies toward the forced frequencies may lead the structure to failure. Vibration analysis of a beam with multiple cracks was investigated in this paper. An un-damped beam with several numbers of cracks was traversed by moving mass with constant speed. Boundary conditions were simply supported and Euler Bernoulli beam theory was considered. In order to solve the vibration analysis, Assumption Mode Method was used and then Transfer Matrix Method (TMM) was applied in order to simulate the cracked beam by calculating the natural frequencies. Maximum deflection and natural frequencies of beam for multiple numbers of cracks in different position was investigated and compared. It was concluded by increasing number of cracks in the beam maximum deflection increase while natural frequencies decrease. It was observed that for the case when the mass moves from left to right, crack attendance in the left side of the beam cause more deflection in compare with symmetrical position in the right side. By increasing number of cracks the deflection of mid-point of the beam takes longer time to reach to the maximum point which is because of the attendance of discontinuity in the beam. All results are compared with those which are available in the literature.
Keywords: assumption mode methods, multiple cracked beams, transfer matrix method.
144
Session 24: Engineering Education/Composites Paper No: 171 Time: 1540 – 1600 Venue: Napier G04 Chair: Dr Ching-Tai Ng Presenter: Colin Kestell
“If I record my lectures, no one will attend my class”: The transition to multi-modal delivery in Applied Mechanics Education Colin Kestell*, Steven Grainger and Dorothy Missingham
School of Mechanical Engineering, The University of Adelaide, South Australia *Corresponding author. Email: [email protected]
Abstract: Contemporary teaching technology provides Applied Mechanics students with the freedom and flexibility to independently learn outside of the lecture theatre at their own convenience. Learning Management Systems (LMS), which have evolved through the needs of distance education and online education provision, now also offer a powerful means to add additional value to face-to-face education. When used appropriately and effectively, these systems have the potential to create an extremely broad and rich, blended learning experience of multi-modal delivery. However, in response to the pioneers who have demonstrated these possibilities, students are now increasingly insisting that all of their course material should be readily available online. Universities are responding to these market demands by persuading academics to embrace e-learning tools, particularly with respect to the recording of lectures. Consequently, it is of little surprise that there is now an arsenal of bemusing technologically complex systems, that lecturers can now choose from, in order to rise to this challenge and broadcast, or publish online. Nonetheless, it cannot be claimed that all lecturers employ the use of this new technology with the same level of enthusiasm as the students, nor perhaps are able to effectively meet their expectations en mass. But why? This paper addresses two hypotheses that seem apparent during a transition from traditional lecturing methods to multi-modal delivery: A lack of opportunity to embrace the technology and a fear that online material will prevent students from attending lectures; the latter of which is often fiercely debated.
The use of new lecture theatre technology, which assists in the creation of online multi-modal delivery, is often led by innovative academics, rather than through the strategic leadership of an institution, and it is these individuals who become the ‘beta testers’, that overcome the difficulties of operation, amidst a highly stressful work environment. Those that choose to follow must re-tread these same pathways amidst the same handicaps, which is not conducive to widespread, nor consistent usage. Amidst an institutional culture that simply insists upon recorded lectures, students might assume that it is generally safe not to attend lectures, and in such cases academics that fear that lecture attendance will decline are correct. However, a strategically determined blend of multi-modal deliveries, in a blended learning environment, in which e-learning material obviously compliments lecture attendance, will result in a far deeper, broader and hence richer learning experience for the student. The authors conclude that teaching staff will require more direct support in establishing a richer e-learning culture, if this is to strategically and effectively blend with face to face learning opportunities. Lecture attendance may fall, but this should only occur if it does not matter. If lecture attendance remains important, then students must see additional value in attending, rather than perceive it as simply a repeated opportunity to view what is online.
Keywords: educational technology, engineering education, on campus teaching, online learning.
145
Session 24: Engineering Education/Composites Paper No: 019 Time: 1600 – 1620 Venue: Napier G04 Chair: Dr. Ching-Tai Ng Presenter: Zhongxiao Peng
Teaching first year engineering dynamics at a small and large Australian University Zhongxiao Peng* and Nicole J. Kessissoglou School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, Australia *Corresponding author. Email: [email protected]
Abstract: Engineering dynamics is a core, fundamental course for all undergraduate mechanical engineering students. This paper compares the teaching practice of engineering dynamics at two different Australian universities, corresponding to a small university with a majority of local students and a large university with a relatively high percentage of international students. Very similar course contents and assessments were delivered at the two universities. However, the pass rates at the respective universities were very different. This paper describes the mechanics courses at the two universities and observes the differences between the respective pass rates.
Keywords: course assessments, course content, engineering dynamics, teaching outcomes.
146
Session 24: Engineering Education/Composites Paper No: 041 Time: 1620 – 1640 Venue: Napier G04 Chair: Dr. Ching-Tai Ng Presenter: Craig Willis
Improved student engagement in civil and mechanical engineering using a professional peer feedback process Craig R. Willis1*, Bernadette A. Foley1 and David G. Wilson2 1 School of Civil, Environmental and Mining Engineering, The University of Adelaide, Australia 2 KBR (Kellogg Brown & Root Pty Ltd), Adelaide, Australia *Corresponding author. Email: [email protected]
Abstract: Preparing students for professional life and providing them with meaningful feedback on their work are two important pedagogical objectives that challenge educators in engineering and other disciplines alike. To achieve these objectives, an initiative was developed to incorporate a key professional process into engineering curricula, through industry collaboration. A design verification process was introduced into two undergraduate courses at Levels I and III, for civil and mechanical engineering, respectively. Verification is more robust than self-checking (which generally only determines the mathematical correctness of calculations), as it examines whether a proposed design output is practical and meets the design objectives. The verification process was introduced into an assessment task where students worked in groups to construct and test a model structure. Design of the structure was based on self-checked calculations and a peer verified design drawing. The peer feedback from the verification process allowed the final model to be improved, compared to the original design, prior to construction and testing. The verification process has similar characteristics to a cyclical feedback strategy and is a form of peer feedback, which have both been demonstrated to improve student learning through increased engagement and reflection. Students perceived that the verification process improved their understanding of the course material and the importance of quality management. They also acknowledged the role of verification in improving their constructed models, compared to the original designs.
Keywords: engagement, peer feedback, verification, checking, quality management.
147
Session 24: Engineering Education/Composites Paper No: 186 Time: 1640 – 1700 Venue: Napier G04 Chair: Dr. Ching-Tai Ng Presenter: Mohammad Sayem Uddin
Finite element modelling and analysis of a filament wound spinning composite disk Md Sayem Uddin*, Evgeny V. Morozov and Krishna Shankar School of Engineering and Information Technology, The University of New South Wales, Canberra BC ACT 2610, Australia *Corresponding author. Email: [email protected]
Abstract: A composite flywheel is the most effective mechanical energy accumulator with maximum specific energy storage capacity that offers high power and energy densities without reduction in capacity under repetitive charge-discharge cycles. Composite flywheels can attain much higher rotational speed than metallic ones and consequently provide the increase in performance and service life in different applications. This paper presents the finite element modelling and analysis of a special type of filament wound spinning composite disk having two angle-ply layers made of fibre reinforced composite material. To achieve desirable stress fields in the rotating disk under certain conditions, material properties are tailored by orientating fibre paths. Each filament wound layer of the disk is composed of two antisymmetric interlaced plies with opposite orientations of fibres. The filament wound disk has inbuilt mosaic patterns generated due to filament winding process. To demonstrate the effect of filament wound mosaic patterns on the stress state in the spinning composite disk, fibre paths in a single annular orthotropic rotating disk have been modelled using ANSYS. Elastic stress analyses have been performed for the disks with different mosaic patterns. The results have been compared with those obtained using conventional finite element modelling approach. The comparison of the results clearly demonstrates the associated effect of the mosaic pattern structure on the stress distribution in the filament wound rotating disk.
Keywords: flywheel, filament winding, kinetic energy, mosaic pattern, spinning composite disk.
148
Session 25: Fracture and Solid Mechanics Paper No: 141 Time: 1540 – 1600 Venue: Napier 102 Chair: Dr. Sabrina Vantadori Presenter: Donghoon Chang
Plasticity-induced crack closure model for two collinear cracks in plates of arbitrary thickness Donghoon Chang* and Andrei Kotousov School of Mechanical Engineering, University of Adelaide, South Australia *Corresponding author. Email: [email protected]
Abstract: Fracture and fatigue assessment of structures weakened by multiple site damage, such as two or more interacting cracks, is currently a very challenging problem. The main objective of this paper is to develop a mathematical model and an approach to investigate fracture behavior of two through-the-thickness collinear cracks of equal length in a plate of arbitrary thickness under remote cycling loading. The developed mathematical model of the problem under consideration is based on the classical strip yield model and plasticity induced crack closure concept. The approach utilises the fundamental solution for an edge dislocation in a plate of finite thickness and the distributed dislocation technique to obtain an effective and accurate solution to the system of governing equations. The obtained results show a very good agreement with the previously published analytical solutions for limiting cases. In particular, the new results confirm that the crack closure behavior and the opening stress variation in the case of two collinear cracks are significantly dependent on the separation gap between two cracks as well as the plate thickness.
Keywords: collinear cracks, crack interaction, distributed dislocation technique, multiple site damage, plastic collapse, plasticity-induced crack closure, plate thickness effect, strip yield model.
149
Session 25: Fracture and Solid Mechanics Paper No: 196 Time: 1600 – 1620 Venue: Napier 102 Chair: Dr. Sabrina Vantadori Presenter: Stuart Wildy
Bending strain measurements utilising a scanning laser Doppler vibrometer Stuart J. Wildy1*, Andrei G. Kotousov2, Ben S. Cazzolato2 and John D. Codrington2 1 School of Computer Science, Engineering and Mathematics, Flinders University 2 School of Mechanical Engineering, University of Adelaide *Email: [email protected]
Abstract: This paper presents an investigation into the accuracy of 1D scanning laser Doppler vibrometry in measuring quasi-static surface strain of an aluminium beam specimen, induced by bending. The formulation and experimental setup of the strain measurement technique utilised in this research is presented, as well as the approach used to evaluate the accuracy of the technique. Finally, the affect various parameters have on the accuracy of the technique is presented, including the parameters of the numerical method, spatial interval between measurement points and amplitude of loading.
Keywords: bending strain measurement, scanning laser Doppler vibrometry, Savitzky-Golay differentiator.
150
Session 25: Fracture and Solid Mechanics Paper No: 045 Time: 1620 – 1640 Venue: Napier 102 Chair: Dr. Sabrina Vantadori Presenter: Ribelito F. Torregosa
Application of Bayesian updating to the risk analysis of aircraft structures Ribelito F. Torregosa* and Weiping Hu Air Vehicles Division, Defence Science and Technology Organisation, 506 Lorimer Street, Fishermans Bend, Victoria, Australia, 3207 *Corresponding author Email: [email protected]
Abstract: For the continued safe operation of aircraft within and beyond the design lives, it is vital to quantify the risks involved. One of the risks is the probability of failure of critical structural components by sudden fracture following accumulated fatigue damage. The key factors that affect the risk of fracture are the distributions of the initial flaw sizes at the critical locations on the aircraft and their subsequent evolution under service load, both of which are difficult to determine to a desired accuracy and certainty. In this paper, a new method is proposed to improve the accuracy of the probabilistic risk analysis of aircraft structures by progressively updating the distribution of the initial flaws based on subsequent observations. Specifically, the current flight hours of an aircraft are used to update the initial assumption of the distribution of the initial flaw sizes, based on the Bayes’ theorem. A specific case was used to demonstrate the capabilities of the method. This research contributes to the continued efforts by the Defence Science and Technology Organisation to improve and enhance structural integrity assessment of military aircraft, in support of the Australian Defence Force.
Keywords: fatigue fracture, probabilistic, reliability, structural risk analysis.
Additional Papers not Presented
152
Paper No.: 23
Modelling shear behaviour of EPS-sand based on elliptic-parabolic yield surfaces model An Deng1* and Beibei Sun2 1 School of Civil, Environmental and Mining Engineering, IMER, The University of Adelaide, Australia 2 Geotechnical Research Institute, Hohai University, China *Corresponding author. Email: [email protected]
Abstract: A composite geomaterial was formed by blending expanded polystyrene (EPS) bead with fine sand at designated proportions, known as EPS-sand. The geomaterial is light in weight, which enables the reduction in loads, overburdens or lateral earth pressures acted on infrastructure systems when the geomaterial is placed as a backfill in the systems. Research on the stress-strain relationship of the geomaterial is necessary, which guides the design and sustainability of the systems constructed with the geomaterial. Based on elliptic-parabolic yield surfaces model, incremental stress-strain equations were established to characterise mechanical response of the material. Both elastic and plastic strains were taken into account in the equations. In particular, the plastic strain was derived in terms of the shear dilation/contraction trend of the material which was associated with the mixture proportion of the composite mixture and the confining pressures loaded on the material. A series of samples were subjected to consolidated drained triaxial compression tests, the results of which were used to verify the derived stress-strain equations. It is indicated that the equations well approximate the deviator stress-axial strain-volumetric strain of the geomaterial, meaning that the incremental stress-strain equations are able to reflect the critical mechanical properties of the materials, i.e. elastic-plasticity, dilation and contraction.
Keywords: composite geomaterial, EPS bead, sand, triaxial shear, stress-strain relationship, modelling.
153
Paper No.: 190
Evaluation of existing models of FRP-to-concrete debonding failure Ardalan Hosseini1*, Davood Mostofinejad2 1 Graduate student, Department of Civil Engineering, Isfahan University of Technology (IUT), Iran 2 Professor, Department of Civil Engineering, Isfahan University of Technology (IUT), Iran *Corresponding author. Email: [email protected]
Abstract: Externally strengthening of existing reinforced concrete (RC) structures has been accomplished using different materials and techniques. Over the last decade, an increase in the application of fibre reinforced polymers (FRPs) has been observed among various strengthening materials because of their excellent engineering properties. All the FRP strengthening techniques rely on adhesively bonding external tensile FRP composites on the structural element surfaces. However, the most prominent challenge of the technique is premature debonding of FRP sheets from concrete substrate. Consequently, lots of analytical and experimental studies were conducted to investigate debonding failure phenomenon and some analytical and practical models were proposed to predict FRP-to-concrete bond strength. Consequently, the main intention of the current study is to evaluate existing guideline models of FRP-to-concrete bond capacity, including ACI 440.2R-08, fib Bulletin 14 and HB 305-2008. To do so, 10 concrete specimens with dimensions of 150 × 150 × 350 mm were cast and externally strengthened using CFRP composites through wet lay-up process. Specimens were then subjected to single-shear bond test and failure debonding load for each specimen was obtained. The experimental results of the current study show the ability of the Chen and Teng’s model (HB 305-2008 and ACI 440.2R-08) in more precise FRP-to-concrete bond capacity.
Keywords: bond strength models, debonding failure, externally bonded reinforcement (EBR), fibre reinforced polymer (FRP), single shear test.
154
Paper No.: 197
Effects of suction on flow characteristics around circular cylinders based on numerical modelling Abdol R. Kabiri- Samani1 and Anahita Jouzdani2*
1 Associate Professor, Department of Civil Engineering, Isfahan University of Technology, Iran 2 PhD Candidate, Department of Civil Engineering, Isfahan University of Technology, Iran *Corresponding author. Email: [email protected]
Abstract: Hydrodynamic aspects of flow field around a bluff body are of the common concerns in fluid dynamics and fluid- structure interaction and have been the subject of various experimental and numerical studies. This kind of flow is apparent in many engineering problems such as flow around the cylinders of various shapes. Considering the viscous flow features, investigating the boundary layer separation, drag forces and separation control methods become more essential. The present study mainly focuses on boundary layer modelling and also on controlling the separation of boundary layer using a uniform and continuous suction as an active boundary layer separation control technique. Numerical investigation was performed based on a finite difference scheme to solve the vorticity transport equation. Accordingly, the time dependent flow of incompressible viscous fluid around the circular cylinders was modelled. The flow regime Reynolds numbers were less than 300. The effects of suction on stabilizing flow field have also been investigated and the separation angle has been evaluated. In addition, the flow field as well as velocity field of controlled and uncontrolled flows were compared. Results show that for a laminar flow, controlling the boundary layer by suction is a very effective method to reduce the drag force and pressure drop.
Keywords: boundary layer control, finite difference method, suction, vorticity transport equation.
155
Paper No.: 217
Crack monitoring of RC beams using digital image analysis technique
Ardalan Hosseini1*, Davood Mostofinejad2 and M. Hajialilue-Bonab3 1 Graduate student, Department of Civil Engineering, Isfahan University of Technology (IUT), Iran 2 Professor, Department of Civil Engineering, Isfahan University of Technology (IUT), Iran 3 Associate Professor, Department of Civil Engineering, University of Tabriz, Iran *Corresponding author. Email: [email protected]
Abstract: Conventional crack-width measuring techniques such as utilizing demountable mechanical strain gauge (demec gauge), linear variable differential transformer (LVDT) and crack width measuring microscope have been widely used in structural tests all over the world. Despite some certain benefits of these conventional measuring techniques such as simple use, high accuracy and real-time data logging, there are some limitations related to high cost, time-consuming setup and extra charges for data acquisition. The aforementioned drawbacks have led researchers to develop non-contact measuring techniques. Particle image velocimetry (PIV) is a recently developed displacement measuring technique in the field of experimental fluid mechanics and geotechnical tests. Due to excellent ability of the PIV technique in displacement measurements, the intention of the current study is to show the potential of the technique in crack-width measurements of RC beams. To do so, two reinforced concrete (RC) beam specimens with dimensions of 120 ×140 × 1000 mm were cast and subjected to four-point flexural loading. Successive digital images were taken from each specimen during loading process and different cracks of each specimen were monitored using PIV analysis. The results show that the PIV technique can be widely used as an alternative to conventional techniques for crack monitoring of RC members during test process.
Keywords: bending test, crack-width, image analysis, particle image velocimetry (PIV), RC beam.
156
Paper No.: 235
Application of image processing method in experimental modeling of one dimensional dam break wave Anahita Jouzdani1* and Abdol R. Kabiri- Samani2 1 PhD Candidate, Department of Civil Engineering, Isfahan University of Technology, Iran 2 Associate Professor, Department of Civil Engineering, Isfahan University of Technology, Iran *Corresponding author. Email: [email protected]
Abstract: Recently, ample numerical/ analytical/ experimental studies have been performed on dam break phenomenon and its possible consequences on downstream lands. Most of experiments have been carried out in straight flume equipped with a gate. A rapidly removing gate simulates the dam break phenomenon in a small scale. Present study focuses on experimental modeling of dam break phenomena and concerns the downstream initial conditions effects on the dam break wave behavior. Also the image processing technique is employed to investigate the hydraulic characteristics and propagation pattern of the flood wave. The results show that the ratio of downstream water depth to the upstream water depth has significant effect on the flood wave behavior. Also, the downstream initial water depth is another effective parameter on flood wave propagation and celerity which dictates the jet shape. Comparing the results with those of former experimental methods shows that the image processing technique is a useful method to investigate the dam break wave characteristics and similar hydraulic phenomena.
Keywords: dam break, experimental modeling, image processing technique.
157
Authors and Papers Index
Main Author Paper # Main Author Paper #
Abdol-Reza Kabiri- Samani 197 Iuliia Karachevtseva 133
Aditya Khanna 148 Jendi Kepple 6
Alin Nioaţă 87 Jesús Toribio 149, 150
Amanullah Choudhry 122 Jiahua Yang 68
Anahita Jouzdani 235 Jiawen Su 125
Andrei Kotousov 5 Jinchen Ji 180
Andrey Kartavykh 191 Jinglai Wu 188
Andrey Vasiliev 167 Jonny Latuny 104
Anthony Sexton 77, 78 Karthik Ram Ramakrishnan 79
Arcady Dyskin 115 Keiko Natori 211
Ardalan Hosseini 190, 217 Lav Deshpande 120
Ben Speijers 129 Leonard L Koss 24
Cain Doherty 176 Liangchi Zhang 34
Cătălin Iancu 59 Lifu Wang 155
Ching-Tai Ng 146 Ling Yin 204
Chong Y. Wong 56 Lloyd Fletcher 73
Christopher Thang 70 Luiz Bortolan Neto 81
Chun. H. Wang 172 Mahinda Kuruppu 112
Colin Kestell 171 Majed Masmali 106
Craig Willis 41 Manudha T. Herath 100
Dan Dobrotă 118, 119 Matthew Lamb 76
Daniel Ainalis 18 Md. Sayem Uddin 186
Daniel Searson 47 Mehmet Yetmez 75
Daniel Yuen 183 Mei Cheong 29
Daren Peng 166 Mei Liu 31
David Eager 25 Michael Sek 222
Donghoon Chang 141 Minli Yu 22
Elena Pasternak 138 Mohammad Khan 182
Farzin Ghanadi 69 Mohammad Uddin 162
Fengzai Tang 33 Mohammadali Farjoo 232
Filippo Berto 26 Mohsen Askari 219, 220
Gareth Forbes 147 Monis Kazmi 140
Gayan Kahandawa 215 Mridul Ashish Pramanik 246
Gheorghe Amza 92 Muhammad Arif Ashraf 202
Heung Fai Lam 71, 228 Narasimha Murthy Thota 209
Hitoshi Takagi 116, 194 Nik Abdullah Nik Mohamed 43
Holger Roser 187 Nima A. Zanjani 64, 65
Huayi Peng 58 Nixon Kuruvila 132
Igor Shufrin 131 Paul D Walker 159
158
Main Author Paper # Main Author Paper #
Pavlo Selyshchev 226 Shuai He 48
Qingyu Yao 67 Sivakumar DharMalingam 53
Rami M.A. Al-Dirini 82 Stefano C. Meliga 51
Reza Alebrahim 214 Stuart Wildy 196
Reza Shahmiri 142 Sudharshan Venkatesan 54
Rhys Jones 170 Tandy Pok 52
Ribelito Torregosa 45 Thomas Lillicrap 203
Robert Randall 240 Timothy Paul Hutchinson 89
Roger Dennis 144 Vahid Vakiloroaya 117
Roslina Mohammad 212 Vladimir Ginkin 207
Salah Shalouf 39 Weidong Liu 35
Sebastian Davey 61, 62 Wern Han Ong 177
Sergey Lurie 152 Xiaofei Wang 199
Seyed Saeid Hashemi 98 Yunpeng Xue 11
Shah Rahman 255 Zhen Luo 113
Zhongxiao Peng 19, 46
159
Authors and Pages Index A
Adams, R. D., 28
Ainalis, D. T., 111
Aizikovich, S., 84
Alebrahim, R., 143
Amza, G., 98, 110, 133
Arao, Y., 67
Arjomandi, M., 114, 116, 117
Ashraf, M. A., 50, 124
Askari, M., 138, 139
Aydin, H., 81
B
Berto, F., 36, 86
Bickerton, S., 129
Birzer, C. H., 113
Bistamam, M. S. A., 92
Bondoc, K., 140
Bortolan Neto, L., 119
Bottomley, I. J. M., 37
Bradford, R. A. W., 37
Brodie, G., 107
C
Cantwell, W., 108, 126, 128, 132
Carpinteri, A., 31
Cazzolato, B. S., 114, 149
Chang, D., 148
Chapman. C., 140
Cheong, M. C., 113
Chiu, W. K., 64, 80
Choudhry, A., 116
Codrington, J. D., 95, 149
D
Das, R., 45, 108, 128, 129
Davey, S., 108, 128, 132
Dennis, R. J., 37
Deshpande, L. G., 39
DharMalingam, S., 52
Dixon, A., 127
Dobrotă, D., 90, 98, 110, 133
Doherty, C., 64
Doolan, M., 126, 132
Du, H., 104
Dyskin, A. V., 54, 55, 85, 142
Dzenis, Y., 32
E
Eager, D., 140
Eepaarachchi, J. A., 47
Elambasseril, J., 66
Entwistle, R. D., 41, 53
Erdogan, H., 81
Escuadra, J., 34
F
Farjoo, M., 38
Feng, N., 40
Flaim, C., 59
Fletcher, L., 58
Foley, B. A., 146
Forbes, G. L., 53
Funatsu, T., 120
G
Ganina, S. M., 99, 100
Ghanadi, F., 114
Ghomashchi, R., 91
Ginkin, V. P., 99, 100
González, B., 34, 77
Grainger, S., 144
Guerard, S., 124
Guzzomi, A., 103
H
Ha, Q. P., 109
Hafizi, M. Z., 106
Hahn, E. J., 40
Hajialilue-Bonab, M., 155
Hashemi, S. S., 121
He, S., 79
Herath, M. T., 115
Hesterman, D., 103
Hosseini, A., 153, 155
Howard, I., 53
Hsieh, T. H., 29, 30
Hu, Q., 78, 82
Hu, W., 150
Hutchinson, T. P., 48, 125
160
I
Iancu, C., 90
J
Jacob, M. V., 107
Jayaraman, K., 129
Ji, J., 83
Jin, X., 87
Jones, C. M., 112
Jones, R., 35, 72
Josevski, N., 112
Jouzdani, A., 154, 156
K
Kabiri- Samani, A. R., 154, 156
Kahandawa, G. C., 106
Kalyanasundaram, S., 51, 52, 65, 105, 108, 126, 128, 132
Kanapathipillai, S., 70
Karachalios, E. F., 28
Karachevtseva, I., 54
Kartavykh, A.V., 99, 100
Kazmi, S. M. R., 129
Kelly, D. W., 137
Kelso, R., 117
Kendall, M. A. F., 59
Kepple, J. I., 137
Kessissoglou, N. J., 145
Kestell, C., 144
Khan, M. N., 135
Khanna, A., 118
Kinloch, A. J., 29
Koss, L. L., 88
Kotousov, A., 36, 86, 91, 95, 97, 118, 119, 148
Kuruppu, M. D., 120
Kuruvila, N., 66
L
Lam, H. F., 78, 82, 134
Lamb, M. J., 71
Latuny, J., 41
Lau, K. T., 47, 106
Lau, T., 113
Lazzarin, P., 36, 86
Lee, J. S., 29
Lee, Y. H., 116
Li, H., 42
Li, J., 138, 139
Liew, C. K., 61, 123
Lillicrap, T., 60, 96
Liow, J. L., 68
Liu, M., 74, 76
Liu, W., 76
Lueck, C., 60, 96
Luo, Z., 56, 136
Lurie, S., 73
M
Masania, K., 29, 30
Masmali, M., 42
Mathew. P., 42
Matos, J. C., 34, 77
Mazhar, I., 53
McKee, K. K., 53
Meehan, P. A., 38
Meliga, S. C., 59
Melkoumian, N., 121
Mo, J.O., 116
Mohammad, R., 95
Morozov, E. V., 50, 147
Mostofinejad, D., 153, 155
N
Nakagaito, A. N., 92, 130
Natori, K., 67
Neely, A., 60, 96
Ng, C. T., 63, 97
Nik Mohamed, N. A., 89, 143
Nioaţă, A., 94
O
Ong, W. H., 80
Orton, T. L., 112
P
Pandey, J. K., 92
Parker, A. J., 71
Pasternak, E., 54, 55, 85, 142
Paul, G., 44
Pearce, G. M. K., 137
Peng, D., 72
Peng, H. Y., 134
Peng, Z., 57, 145
Pok, T. W. P., 112
Pramanik, M. A., 70
Prusty, G. B., 115, 137
161
R
Rahman, S. A., 101
Rahman, S. M. M., 68
Ramakrishnan, K. R., 124
Randall, R. B., 39, 43
Ravindra, H. V., 66
Reed, M. P., 44
Rhodes, J., 88
Richardson, S. A., 112
Rose, L. R. F., 63, 79
Roser, H. M., 102
Rouillard, V., 88, 111
Ruan, H., 74, 75, 76, 122, 135
S
Samali, B., 109, 138, 139
Sandvik, A. L., 112
Sawalhi, N. M., 39
Searson, D. J., 48, 125
Sek, M. A., 111, 141
Selyshchev, P., 69
Sexton, A., 52, 126, 132
Shahmiri, R., 45
Shalouf, S. M., 131
Shankar, K, 50
Shankar, K., 124, 147
Sharifian, S., 89, 143
Sheehan, M., 107
Shufrin, I., 55, 85, 142
Singh, P., 107
Singh, S. S. K., 89, 143
Smith, W. A., 30, 43
Soliaev, J., 73
Solnordal, C., 93
Speijers, B., 103
Stevens, M. J., 37
Su, J., 61
Sugakov, V., 69
T
Takagi, H., 92, 130
Takeichi, G., 130
Tanaka, T., 67
Tang, F., 75
Taylor, A. C., 29, 30
Thang, C. Y., 123
Thewlis. D., 44
Thomson, R. S., 137
Toribio, J., 34, 77
Torregosa, R. F., 150
Tuchkova, N., 73
U
Uddin, M. S., 46, 147
V
Vakiloroaya, V., 109
Vantadori, S., 31, 127
Vasiliev, A., 84
Veidt, M., 59, 61, 63
Venkatesan, S., 52, 105
Viot, P., 124
W
Walker, P. D., 101
Wang, C. H., 49
Wang, L., 102, 104
Wang, M., 57
Wang, X., 60, 96
Wang, Y., 136
Wildy, S. J., 149
Willis, C., 146
Wilson, D. G., 146
Wong, C. Y., 93
Wu, J., 56
X
Xu, C., 121
Xue, Y., 117
Y
Yang, J., 62, 82
Yao, Q., 122
Yashima, T., 67
Yetmez, M., 81
Yin, L., 57, 107
Yokota, K., 130
Yu, M., 40
Yuen, D. W. Y., 127
Z
Zander, A. C., 114
Zanjani, N. A., 51, 65
Zhang, J., 131
Zhang, L. C., 74, 75, 76, 87, 122, 135
162
Zhang, N., 30, 56, 83, 101, 102, 104, 136
Zhang, X., 135
Zhao, X., 135
Zhu, B., 101
