2nd International Conference of the - ijsi2014.inegi.up.ptijsi2014.inegi.up.pt/IJSI2014_book.pdf · A Deviatoric Neuber’s Rule and SWT ... The use of optical scanning ... Book of

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2nd International Conference of the

International Journal of Structural Integrity

Funchal, Madeira, Portugal

1 - 4 September, 2014

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Committees

Chairmen

Pedro Moreira, INEGI/FEUP, Portugal (chairman)

Paulo Tavares, INEGI/FEUP, Portugal (co-chairman)

Organizing Committee

Chris Rodopoulos, Monash University, Australia, and IJSI editor-in-

chief

Joaquim Silva Gomes, University of Porto, Portugal

Mário Vaz, University of Porto, Portugal

Paulo Tavares de Castro, University of Porto, Portugal

Sérgio Tavares, INEGI, Portugal

Scientific Committee

D Angelova, University of Chemical Technology and Metallurgy – Sofia,

Bulgaria

Charis Apostolopoulos, University of Patras, Greece

J N Bandyopadhyay, Indian Institute of Technology, India

Leslie Banks-Sills, Tel-Aviv University, Israel

Simon Barter, DSTO, Australia

Claudio DalleDonne, EADS Deutschland GmbH, Germany

Paulo de Castro, Universidade do Porto, Portugal

Bahram Farahmand, Technical Horizon Inc, USA

A Giannakopoulos, University of Thessaly, Greece

M M I Hammouda, Al-Azhar University, Egypt

Seung Ho Han, Dong-A University, South Korea

Peter Horst, Technische Universität Carolo-Wilhelmina zu

Braunschweig, Germany

Y H Huh, KRISS, Korea

Madabhushi Janardhana, Directorate General Technical Airworthiness,

RAAF, Australia

Rhys Jones, Monash University, Australia

J P Komorowski, CNRC, Institute for Aerospace Research, Canada

Daniel Kujawski, Western Michigan University, USA

G Labeas, University of Patras, Greece

L Marsavina, Universitatea Politehnica Timirosa, Romania

A Navarro, University of Seville, Spain

Sp. Pantelakis, University of Patras, Greece

P Peyre, LALP/CNRS, France

A Pistek, Brno University of Technology, Czech Republic

B Purna Chandra Rao, Indira Gandhi Center for Atomic Research

(IGCAR), India

Stephen Reed, Ministry of Defence, Defence Science and Technology

Laboratory, UK

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R Ritchie, University of California, Berkley, USA

Hamid Saghizadeh, The Boeing Company, USA

W Soboyejo, Princeton University, USA

C Soutis, University of Sheffield, UK

Koji Takahashi, Yokohama National University, Japan

V Troshchenko, National Academy of Sciences, Ukraine

Jaime Tupiassú Pinho de Castro, PUC-Rio, Brazil

L Wagner, Technische Universität Clausthal, Germany

Geng Sheng Wang, FOI, The Swedish Defence Research Agency,

Sweden

Ali Yousefiani, The Boeing Company, USA

Published by:

INEGI – Instituto de Engenharia Mecânica e Gestão Industrial

Front cover figures credits:

S M Tavares

Editor IJSI2014 book of abstracts: PMGP Moreira and PJS Tavares

ISBN: 978-972-8826-31-4

http://ijsi2014.inegi.up.pt

http://ijsi2014.inegi.up.pt/

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Sponsors

Institute of Mechanical Engineering and Industrial Management

EASN – European Aeronautics Science Network

ESIS – European Structural Integrity Society

EURASEM -.European Society of Experimental Mechanics

SPM – Sociedade Portuguesa de Materiais

Official Carrier TAP Portugal

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Grupo ALAVA Ingenieros

Prudente & Tavares Consulting

Regional Government of Madeira

International Journal of Structural Integrity

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Book of abstracts of the 2nd International Conference of the International Journal of Strucutral Integrity________

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Contents

Committees .......................................................................................................... 2

Sponsors ............................................................................................................... 4

Contents ............................................................................................................... 6

Welcome from President of the Institute of Mechanical Engineering and Industrial

Management ...................................................................................................... 11

Welcome from Conference Chairs ....................................................................... 12

Conference Overview .......................................................................................... 13

Conference site ................................................................................................... 15

About Madeira .................................................................................................... 16

Meetings rooms .................................................................................................. 17

Plenery Invited Speakerss.................................................................................... 18

Prof. Peter Horst, ............................................................................................ 18

The significance of the interaction of stability and damage propagation in

metallic and composite panels ................................................................... 18

Prof. Daniel Kujawski ....................................................................................... 19

A Deviatoric Neuber’s Rule and SWT Parameter for Fatigue Analysis......... 19

Prof. Chris Rodopoulos .................................................................................... 21

Optimising Controlled Shot Peening Parameters for Optimum Fatigue Life21

Prof. Malgorzata Kujawinska ........................................................................... 22

Full-field optical methods for measurements and monitoring of industrial

structures.................................................................................................... 22

Prof. Carmine Pappalettere ............................................................................. 24

Challenge on Application of Titanium Alloys on Aeronautic Structures ...... 24

Prof. Mário Vaz ............................................................................................... 26

Structural Monitoring and Biomechanics.................................................... 26

IJSI2014 Program ................................................................................................ 28

Program Overview .......................................................................................... 28

Technical Program ........................................................................................... 29

Abstracts ............................................................................................................. 40

Session 1 ............................................................................................................. 41


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Friction Stir Weldbonding of Aluminum Joints ................................................. 42

The effect of welding direction in the fatigue life of aluminium fs welded lap

joints ............................................................................................................... 43

Mechanical Fracture Behaviour of Laser Beam-Welded AA2198 Butt-Joints and

Integral Structures........................................................................................... 44

Influence of the Kissing Bond Defect to the Fatigue Life in Friction Stir Welds of

2024 Aluminium Alloy ..................................................................................... 45

Influence of tool geometry and process parameters on defect formation in lap

joining by friction stir welding of very thin plates ............................................ 46

Shoulder Design Options for FSW Lap Joints of Plastic Sheets .......................... 47

Session 2A ........................................................................................................... 48

Combining nanocrystallisation processes with a subsequent thermomechanical

processing – interfacial oxidation .................................................................... 49

Structure, electromagnetic wave absorption and mechanical behavior of

carbonaceous nanofillers modified polymer composites ................................. 50

Hydrogen influence on fatigue in a Cr-Mo steel ............................................... 52

Structure-property relationships of PC/ABS blend composites with nanoclay .. 54

Evaluation of nitriding process effects on cold worked AISI 304 and 316

austenitic stainless steels ................................................................................ 56

Session 2B ........................................................................................................... 57

Safety assessment of helmets for roller hockey goal keepers........................... 58

Mechanical Behavior Characterization of a Lumbar Vertebra; With or Without

Cement Reinforcement ................................................................................... 59

Structural integrity of a Maryland dental bridge .............................................. 61

Comparison of mechanical behaviour between two brands of extra oral force

modules .......................................................................................................... 63

The application of epoxy paint for improved aesthetics in partial dentures’

frameworks ..................................................................................................... 65

Effect of impressions disinfection on the surface detail reproduction .............. 66

Session 3A ........................................................................................................... 67

Elasto-plastic analysis of structures using an Isogeometric formulation ........... 68

Practical Applications of the SIFCM ................................................................. 69

Multi-objective Fatigue Life Optimization using Tabu Genetic Algorithms ........ 70


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Induction of Through-Thickness Compressive Residual Stress Fields in thin

Al2024-T351 Plates by Laser Shock Processing................................................. 72

Session 3B ........................................................................................................... 74

Structural Assessment of Fine-scale Structures Produced by Complex Metal

Forming Processing ......................................................................................... 75

Damage tolerance improvement of laser beam welded fuselage structures via

crenellations ................................................................................................... 76

Mechanical Behavior of Friction Stir Welded Butt Joints .................................. 77

Manufacturing and characterization of nanostructured Al-Si-Si3N4-C composites

for high-wear application ................................................................................ 79

Development of multi-layer fibrous composites for fire resistant and sound

insulating doors ............................................................................................... 80

Session 4A ........................................................................................................... 81

Cold plasma treatment of polymeric matrix composites .................................. 82

Modification of metallic surfaces by duplex treatments involving severe shot

peening, pulsed electron beams and nitriding. ................................................ 84

A study on the effect of weld induced residual stresses and the influence of

weld sequencing of centrifugal extractor rotating bowl using numerical

simulation and experimental validation ........................................................... 86

Internal Expansive Reactions in Concrete Structures – Deterioration of the

mechanical properties ..................................................................................... 88

A comparison between the deformation behaviour of dissimilar AA2024‐

T3/AA7050‐T7651 welds produced by Stationary Shoulder Friction Stir Welding

and standard Friction Stir Welding .................................................................. 90

Session 4B ........................................................................................................... 91

Considerations on the choice of the drilled hole diameter in ESPI-HDM residual

stress measurements in Ti6Al4V ...................................................................... 92

Experiment Research and Application on Super-Retarding Mortar .................. 94

Characterization of orthotropic stiffness components of Pinus pinaster from

heterogeneous plate bending tests ................................................................. 95

Sloshing effect on the dynamic behavior of large capacity horizontal cylindrical

tank due to seismic excitation and it's qualification ......................................... 97

Fatigue cracks thermal patterns ...................................................................... 99

Session 5A ......................................................................................................... 100

Predicting the fatigue life of mechanical components using continuum damage

mechanics (cdm): application to a railway axle .............................................. 101


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Dynamic models in stress wave dispersion filtering in the Hopkinson Pressure

Bar ................................................................................................................ 102

Sensitivity of Material Parameters on the Fatigue Crack Growth Calculations 103

Structural analysis of a cross car beam using finite element models .............. 105

Session 5B ......................................................................................................... 107

Evaluation of Semi-Ellipsoidal Wall Thinning on Back Surface of Plate by Direct-

Current Potential Difference Method ............................................................ 108

Internal residual stresses of tungsten-CFRP hybrid laminates ........................ 110

Dynamic parameters and dissipative capacity of a pultruded FRP spatial

structure ....................................................................................................... 112

Sloshing forces in a 3D liquid waste storage tank under harmonic wave

excitation ...................................................................................................... 113

Session 6A ......................................................................................................... 115

Application of the Strain-Based FAD to Failure Assessment of Surface Cracked

Components.................................................................................................. 116

Theoretical and experimental model for the analysis of a cardan cross.......... 118

Multiscale Simulation Strategy for Low-Velocity Impact on FRP ..................... 119

Structural Deformation Measurements by Image Block Matching Algorithms 121

Session 6B ......................................................................................................... 123

Evaluation of mixed-mode I+II fatigue crack propagation in steels assisted by

DIC ................................................................................................................ 124

Virtual Sensors for SHM using isogeometric piezoelectric finite elements ...... 125

On Monitoring of Mechanical Characteristics of Hot Rolled S355J2 Steel ....... 126

The use of optical scanning methods for testing of thin oxide films deposited on

rough steel substrates ................................................................................... 128

Session 7 ........................................................................................................... 129

System for Fuel Elements Inspection of Nuclear Research Reactor by the Sipping

Method ......................................................................................................... 130

Remote monitoring of an elevated water reservoir using optical fiber

technology .................................................................................................... 132

Thermal Fatigue Behaviour of Polyamides used in Intercoolers ..................... 134

Long term monitoring of a high-speed railway bridge: thermal behaviour ..... 135

Session 8A ......................................................................................................... 137

Keying Effect During Fracture of Stainless Steel ............................................. 138


10

Non-destructive methodology based on magnetic flux density measurement, in

the reversibility domain region, to follow stainless steel embrittement ......... 139

Analysis of the magnetic field integrity of electric machine and construction

structure ....................................................................................................... 141

SIF determination with Digital Image Correlation .......................................... 142

Session 8B ......................................................................................................... 143

Characterization of nickel alloy 600 with ultra-fine structure processed by

severe plastic deformation technique (dpi) ................................................... 144

The effect of size, amount and surface treatment of micro particles of cork on

the toughness of a brittle epoxy .................................................................... 145

Corrosion performance of corrugated stainless steels in mortar partially

immersed in chloride solution for 8 years ...................................................... 147

Fatigue damage evolution and life prediction for metastable austenitic steels

under consideration of martensite phase transformation .............................. 149

Biodegradable composite thermoplastics used in interior parts of aerospace

and automobile products .............................................................................. 150

Session 9A ......................................................................................................... 152

Fatigue Crack Growth Measurement Automation .......................................... 153

Contactless defect detection using two emerging Optical Methods for NDT of

composite structures - Thermography and Shearography .............................. 155

Novel Non-Destructive Testing techniques for structural integrity ................. 157

Structural monitoring of wind turbine blades ................................................ 158

Session 9B ......................................................................................................... 159

Fire resistant coatings for polymeric matrix composites ................................ 160

Evaluation of Advanced Materials in Aircraft Structure .................................. 162

Electromagnetic shielding enclosure built on metallic lightweight structure for

aerospace EMI protection applications - Experimental tests and numerical

simulation - ................................................................................................... 163

Influence of Titanium, Niobium and Aluminium addition on microstructure and

mechanical properties of Ferritic Stainless Steel welds .................................. 164

Designing and optimization of new composite pallet ..................................... 165

Index ................................................................................................................. 167


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Welcome from President of the Institute of

Mechanical Engineering and Industrial Management

Jorge Seabra

Dear Participants in the IJSI-2014 International Conference,

As President of INEGI, it is with great pleasure that I welcome you to the 2nd

Conference of the International Journal of Structural Integrity.

INEGI pledged its commitment to the subject of this conference several years ago,

and has been doing research work in the area that has not gone unnoticed. As an

interface institute between the University and the Industry, we are bound by the

numerous practical issues on the subject brought to our attention by the companies

we partner, the projects we embrace or the discoveries of our scholars and research

teams. Structural Integrity issues arise naturally on real-life parts, and those are

precisely the sort of subjects our industrial partners make a living of, and therefore

we either study or analyse as part of our daily work.

I wish you all a fruitfull meeting and may the consequences of this conference fuel

important work for new researchers and results for the industry and the Society at

large.

Warm regards,

Jorge Seabra


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Welcome from Conference Chairs

Pedro M G P Moreira and Paulo J da Silva Tavares

Dear delegates of the IJSI-2014,

As chairs of the organizing committee of the 2nd Conference of the International

Journal of Structural Integrity, it is with great honour and a touch of unconcealed

excitement that we welcome you to Funchal.

Structural Integrity research has gone through an impressive leap in recent years.

An Emerald journal and a set of conferences fully dedicated to the topic are really

a testimony to both the relevance and increasing level of activity of researchers and

professionals alike.

In organizing this important conference in Funchal, the organizing committee

targeted two very clear objectives that can be summed up as the attempt to create

a lively and fruitful conference environment on one of the most pleasing places in

Portugal. We therefore hope we have, in a simple, humble fashion, contributed to

the advance of the discussion by bringing it to an inspiring and informal

environment where researchers from across the globe are able to convey their

views and vividly confront different perspectives, somehow shining the light from

knowledge where darkness and divergence are customary.

We hope you all are able to seize the day and contribute to this ideal, while

enjoying the little pleasures of Funchal and Madeira, that can't be found

anywhere else on Earth.

Our politesse formula could therefore be no other than, True wishes of fruitful discussions, Pedro Moreira and Paulo Tavares


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Conference Overview

The International Journal of Structural Integrity – IJSI was

launched in 2010 and is published in partnership with the

European Aeronautics Science Network – EASN. The IJSI aims

at a broad coverage of structural integrity issues, including

material characterizations from the fracture and fatigue points to

view, numerical modelling of those phenomena in materials and

real structures, failure analysis methodologies and structural

integrity evaluation criteria. The journal provides a forum for the

key players in this broad area of science and technology, as

universities, research institutes, manufacturing industry,

legislative bodies and government agencies, SMEs, consultancy

and maintenance companies.

The 2nd International Conference sponsored by the journal, will

take place in place in Funchal/Madeira, Portugal on 1 – 4

September, 2014.

The conference aims at being a forum for discussion of current

trends of research in structural integrity, in aeronautics and

space, but also in other sectors of engineering where structural

integrity is a key concern.

Aim and Topics

The conference topics are aligned with the IJSI coverage, and

include but are not limited to:

Advances in Fracture Analysis

Coating Technology and Structural Performance

Design and Structural Assessment of Metallic and

Composite Structures

Durability of Electronic Materials

Durability of Metallic and Composite Structures

Environmental Effects and Structural Performance

Evaluation of Joining Technologies

Examination of Computational Codes for Stress Analysis

and Damage Tolerance

Nanomechanics and nanomaterials


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Non-destructive testing

Probabilistic Approach to Damage Tolerance

Repair Technologies

Scale Effects

Structural Ageing

Structural Health Monitoring

Structural Integrity

Structural Integrity in Nuclear Power Plants

Structural Integrity of Bridges

Structural Performance Evaluation of Metals, Composites,

Hybrids and Polymers

Surface Engineering and Structural Performance


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Conference site

The conference will be held in the beautiful city of Funchal in

Madeira (Portugal), at the Hotel Pestana Casino Park, which is

very convenient and well equipped for conferences in terms of

facilities, transportation and proximity to other hotels.

The Municipality of Funchal extends over a large hill, arranged in

an amphitheater, from the coast up to Pico do Areeiro, situated

at 1818m above sea level. The human occupation of the land over

time was conditioned by the steep slopes. According to the 2011

census, the municipality of Funchal has 111 892 inhabitants,

spread over 10 parishes.

It’s one of the region’s oldest municipalities and Funchal became

a city in 1508 by Royal Charter under D. Manuel I, and has

always done well due to its strong economic, social and cultural

potential.

The city of Funchal has many leisure activities on offer, you can

visit the magnificent monuments, museums and gardens, shop,

explore it’s pretty Portuguese-style cobbled streets or simply

have a pleasant time sitting on a terrace. Don’t miss the chance

to visit the city’s old town, a picturesque historic centre that’s

lively and full of colour. There, along with the various traditional

bars and restaurants, you’ll find the “Open Arts Trail” project.

Unveil more of this municipality’s mysteries at www.cm-

funchal.pt

http://www.pestana.com/en/pestana-casino-park-hotel/pages/home.aspx

https://d.docs.live.net/f55b672812a045c3/www.cm-funchal.pt

https://d.docs.live.net/f55b672812a045c3/www.cm-funchal.pt


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About Madeira

Madeira island is 310 miles from the African coast and 620 miles

from the European continent, which is the equivalent of a 1 hour

30 minutes flight from Lisbon.

The Madeira Archipelago, discovered by the Portuguese in 1418,

is made up of the islands of Madeira, Porto Santo and the

uninhabited islands of Selvagens and Desertas. It is situated

between latitude 32º22’20″ and 33º7’50″ with its longitude

between 16º16’30W and 17º16’38″W.

The island of Madeira has a surface area of 459 square miles (741

km2), (35 miles long and 13 miles wide).

These islands, because of their privileged geographical position

and mountainous relief, have a surprisingly mild climate.

Very mild average temperatures, 25ºC in the summer and 17ºC

in the winter, and a moderate level of humidity, confer upon

these islands exceptional subtropical features.

The seawater temperature is also very mild, because of the

influence of the warm Gulf current, presenting averages of 22ºC

in the summer and 18º in the winter.


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Meetings rooms

Room Lisboa: Lisboa (main), Floor GF

Room Berlinerlin: Berlin, 1st floor

Conference location


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Plenery Invited Speakerss

Prof. Peter Horst,

Technische Universität Braunschweig

Germany

The significance of the interaction of stability and damage

propagation in metallic and composite panels

Abstract

In general two main types of criteria are essential for the sizing of

aircraft structural panels, namely stability and damage tolerance. The

way these criteria act and interact is very different for metallic and

composite building blocks. While interaction of both types of criteria is

relatively clear for composite parts, this is normally not the case for

metallic ones. What is common for both is the fact that if an interaction

occurs, the impact is essential.

This subject is discussed for both cases and some conclusions are drawn.

------------------------------------------------

Peter Horst has a degree in Oceanography from Hamburg University and

Mechanical Eng., special field of Aeronautics, from Technische Universität

Braunschweig. Dr. Horst received his PhD diploma in Mechanical Eng. in 1990

from TU Braunschweig. He worked as research assistant in this University from

1984 to 1990 and Head of “Structure, Repair and Engineering” in Airbus

Deutschland from 1990 to 1998. He currently holds a teaching position in

“Aircraft Design and Lightweight Structures” and heads the Institute of Aircraft

Design and Lightweight Structures, at Technische Universität Braunschweig.


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Prof. Daniel Kujawski

Mechanical and Aerospace Engineering, Western Michigan

University

USA

A Deviatoric Neuber’s Rule and SWT Parameter for Fatigue

Analysis

Abstract

Neuber’s rule and Smith-Watson-Topper (SWT) parameter are the most

widely used approaches in fatigue analyses of notches and mean stress

effects on fatigue life, respectively. It is well known that Neuber’s rule

usually overestimates the notch-root strains, in particular for thick

components or circumferentially grooved shafts under axial tension. On

the other hand, the SWT parameter might be non-conservative for loads

that involve relatively large compressive mean stresses. Such large

compressive mean stresses can develop in notches after overloads.

In this paper, a deviatoric formulation of Neuber’s rule and SWT

parameter are presented. The Neuber’s rule is discussed from an energy

point of view in terms of the total energy, strain energy, and deviatoric

energy densities. The deviatoric formulation of Neuber’s rule results in

elastic-plastic notch-root strains, which correlate fairly well with

published experimental and FEA data. They are upper-bounded by the

traditional Neuber’s rule and lower-bounded by the equivalent strain

energy density method of Molski and Glinka. The deviatoric Neuber’s

rule has a consistent formulation independent of loading mode such as

axial, shear, or multiaxial. Based on an energy interpretation of the

SWT parameter and its analogy with the Neuber’s rule a deviatoric

formulation of the SWT parameter called SWTD is discussed. For

positive mean stresses and moderate negative mean stresses the

traditional SWT parameter and the deviatoric SWTD parameter yields

similar results. On the other hand, for large compressive mean stresses

with a stress ratio R < - 2, the proposed SWTD parameter demonstrates

a fairly good correlation while the original SWT parameter results in

wide scatter. It can be noted that both deviatoric formulations of

Neuber’s rule and the SWTD parameter do not involve or require any

adjustable constants or fitting parameters.

Also, a novel graphical method for analyses of notches and fatigue life

predictions will be demonstrated. This interactive, self-explained fatigue

analysis tool provides rapid practical results, allows their comparisons,

and facilitates a decision process in seeking a sound solution.


20

------------------------------------------------

Daniel Kujawski was educated at Warsaw University of Technology in Poland in

area of Precision Engineering. In 1978 he received Ph.D. degree in Solid

Mechanics at Polish Academy of Sciences. He has conducted research in Poland,

USA, France and Canada. In 1996 joined the faculty in Mechanical and

Aerospace Engineering at Western Michigan University and became Professor in

2003. Prof. Kujawski is recognized for his research in the fields of inelastic

material behavior, fatigue crack growth, stress analysis at notches, and fatigue

life prediction. Author and co-author of more than 140 research contributions,

two books, and four patents. He is a member of the editorial boards of several

international journals. He teaches both undergraduate and graduate courses in

the mechanical behavior of engineering materials, fatigue and fracture.


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Prof. Chris Rodopoulos

Centre of Expertise in Structural Mechanics, Monash University,

Melbourne, Clayton 5800

Australia

Optimising Controlled Shot Peening Parameters for Optimum

Fatigue Life

Abstract

For over 50 years controlled shot peening (CSP) parameters have been

selected on the basis of maximising the depth of residual stresses

independently of their profile, induced cold work, exerted surface

roughness and ductility exhaustion of the near surface. Despite the fact

that relaxation, both in terms of residual stress profile and magnitude is

heavily influenced by the far field stress, manufacturing has repeatedly

failed to engage it in the optimisation process. Similarly, failure of

acknowledging the natural tendency of FCC materials towards short

cracking has led to irrational selection of CSP parameters.

In this work the steps required towards optimising CSP parameters for

over 140 different alloys along with their testing verification is

presented.

------------------------------------------------

Chris Rodopoulos was born in Athens, Greece in 1967. In 1991 he received his

Dipl.-Eng. in Mechanical Engineering from the University of Patras. In 1992 he

received an MSc in Advanced Materials from Nottingham University. In 1996

he completed his PhD from the University of Sheffield. His research interests

are focused on Surface Engineering Treatments, Fatigue Damage Tolerance

Analysis, Theoretical Stress Analysis and Thermomechanical Fatigue of Metal

Matrix Composites. He is the editor-in-chief of the International Journal of

Structural Integrity, and the author of more than 120 papers and four books.

Since 2002 he has led the Interest Group Surface Engineering Treatments with

the European Aeronautics Science Network. He is a member of several

professional organizations, including ASME, AIAA, ESIS and IMechE. During

his career so far he has received 5 awards for research papers. He has strong

collaborations with a number of key research institutes and industrial bodies

including, EADS, Airbus UK, Boeing, Rolls-Royce, Hyundai, NRC-CNRC,

NASA Langley, Applied Ultrasonics, Metal Improvement Company, CLFA,

DLR, NLR, SIKA, Penetron, LAGARGE, etc.


22

Prof. Malgorzata Kujawinska

Institute of Micromechanics and Photonics, Warsaw University of

Technology

Poland

Full-field optical methods for measurements and monitoring of

industrial structures

Abstract

Structural integrity defined as a performance characteristic applied to a

component or a structure is most often provided by a combination of

experimental and numerical studies of an object. The excellent source of

experimental data are optical full-field methods, which deliver

displacement and strain measurements with different sensitivities,

measurement ranges, spatial and temporal resolutions, complexity of

measurement systems and capability to use them in laboratory or

outdoor environments. The optical methods include coherent

(holographic and speckle interferometry, grating interferometry) and

noncoherent image-based methods (moire fringe methods, structured

light methods, digital image correlation, thermovision). However in the

case of engineering structures and the tests performed outside

laboratory, in difficult outdoor conditions noncoherent image based

methods are most often applied. It is mainly due to relatively easy

measurement procedures, less expensive hardware configurations and

big measurement range of investigated quantities.

In the paper the concept of hierarchical and multimodal measurement

system based on an enhanced 3D digital image correlation (DIC)

method supported by thermovision, laser scanning and structured light

methods is described. The most important enhancement is the method

for automatic merging of data distributed in time which allows for long

term monitoring without the necessity to maintain DIC system in

permanent position. Also the correlation between thermal load and 3D

deformations or strains is introduced in the system and the method

allowing for efficient experimental data interaction with FEM modeling

or FEM model validation is described.

Several applications of the optical methods in the structural integrity

analysis are presented and discussed. These include applications in heat-

and-power generating industry (measurements of district heating

pipelines, expansion bellows, drums), building industry (studies of steel

struts and diaphragm walls, halls constructed with metal plate archs,

steel trusses, field containers e.g. for biomass) and in studies of highly

responsible composite structures (e.g. tanks for fluid hydrogen and

canvas paintings).


23

Finally the perspectives of wide implementation of full-field optical

measurement methods in standard structural integrity analysis are

discussed.

Acknowledgements

The financial support from the EU Structural Funds in Poland, within the

project ‘‘Health Monitoring and Lifetime Assessment of Structures’’– MONIT –

POIG.0 101.0 2-00-013/0 8-00 and from the National Centre for Research and

Development in Poland, within the project number 513 G 1143 2740 000 are

gratefully acknowledged.

------------------------------------------------

Prof. Malgorzata Kujawinska PhD DSc., SPIE Fellow, recipient of SPIE Optical

Metrology Award 2013, Professor of applied optics at Warsaw University of

Technology, head of Optical Engineering Division at Institute of Micromechanics

and Photonics, recognized expert on full-field optical metrology and sensing,

image processing and hybrid experimental-numerical methods in experimental

mechanics, material engineering, reverse engineering and multimedia. Author

and co-author of more than 200 papers in recognized scientific journals, one

monograph and several book chapters. Leader of 8 European Projects and

numerous national research and industrial projects. devoted to optical metrology

and development of innovative measurement systems based on interferometric

and noncoherent methods.

M. Kujawinska is the Past President of SPIE – the International Society of

Optical Engineering (2005) and recently is the Vice-President of European

Technology Platform Photonics21.


24

Prof. Carmine Pappalettere

Politecnico di Bari, Dip. di Meccanica, Matematica e

Management, Bari

Italy

Challenge on Application of Titanium Alloys on Aeronautic

Structures

Abstract

The increasing use of titanium alloys in different industrial applications

in chemical, aerospace, naval and biomedical engineering is motivated

by the special properties of this material. Applications of titanium alloys

are very suited for naval constructions where resistance to corrosion is

the most important issue to be considered in the material's selection,

aerospace structures where the main target is to achieve high specific

strength, and orthopedic prosthetic treatments where biocompatibility

between implants and human tissues is mandatory.

In aeronautical industry, the current trend is to explore the possibility

of broadening the field of application of titanium alloys trying to

improve the use of this homogeneous and isotropic metallic material in

place of low-weight composite materials. This is justified in most part by

the high specific strength of titanium alloys. Furthermore, composite

structures are not very easy to be inspected and their mechanical

behavior in the nonlinear regime may be extremely sensitive to the

layup chosen in the design phase.

Welding of titanium alloys is still considered a fairly uncommon process

because industrial applications of these materials cover only the above

mentioned niches where the unique properties of titanium and its alloys

represent the best option in terms of minimizing the lifetime cost of the

structure yet meeting stringent requirements on structural integrity and

safety. However, whilst high quality welded components without

inclusions and distortions and with a mild notch at the weld toe can be

obtained through appropriate selection of welding process parameters, it

should be considered that the weld cord is anyhow a geometric

discontinuity in the structure, which modifies stress distribution.

Furthermore, residual stresses are an unavoidable consequence of the

thermal welding cycle.

Fatigue strength and residual stress level of welded joints are the most

important information needed in aerospace applications of titanium

alloys. Data available in literature are still not sufficient to make design

procedures general and reliable. For this reason, in order to investigate

the mechanical behavior of titanium welded joints and to build a

technical database useful to designers, this work presents some results

recently obtained on joints welded by using different techniques (laser,

hybrid, friction, electron beam).


25

Experimental results of fatigue tests are discussed in terms of both

curves determined experimentally are then compared with fatigue

design curves reported in a recent AWS standard that was specifically

released for titanium welded joints.

Residual stresses are measured by means of the hole drilling method

and/or Xray diffractometer and then correlated with mechanical

response of welded components and microstructure modifications.

In addition to experimental tests, very detailed finite element analyses

are carried out.

------------------------------------------------

Carmine Pappalettere, born in 1949, is since 1990 full professor of Mechanical

Engineering and Experimental Mechanics at Politecnico di Bari (University

Technical School of Engineering and Architecture), Italy. He specialized in

stress/strain analysis of structures with both experimental techniques (Strain

Gages, Photoelasticity, Moiré, Holographic and Speckle Interferometry, Atomic

Force Microscopy, etc) and numerical methods (Finite and Boundary Element

Methods, Non-linear and Non-Convex Problems, Optimization-based Inverse

Analysis, etc). Welded joints, stress concentrations, biomechanical problems are

particular aspects of the above mentioned topics together with the

methodological improvement of experimental techniques for stress analysis and

mechanical characterization of engineering materials and biomaterials. In his

research activity, Prof. Pappalettere has published more than 300 papers in

international journals, edited books and conferences proceedings (100 in

Italian)..


26

Prof. Mário Vaz

Faculty of Engineering of University of Porto

Portugal

Structural Monitoring and Biomechanics

Abstract

The main goal of Biomechanics is the study of the structure and

function of biological systems such as humans, animals, plants, organs,

and cells by using the methods of Mechanics. The characterization of

human locomotion is one of the central issues for its multiple

implications, occupational, leisure, sports and rehabilitation. For this

purpose systems that allow obtaining the forces and displacements

associated with lower limb during gait were built. Platform forces,

ergometers and systems for 3d recording of the movement, based on

multiple images or using inertial devices are currently used in

biomechanics laboratories. Thus a quantitative evaluation of the various

parameters of gait is possible, as is the use of this information in

postoperative rehabilitation in case of injuries or accidents.

On the other hand it is also possible to provide prostheses and orthoses

with systems and sensors to enable register forces and displacements of

interest to outpatient treatments in orthopedics and physiotherapy. The

experience gained over the past two decades with the application of

experimental mechanics techniques in Biomechanics identified a set

cross multidisciplinary needs which LABIOMEP – Laboratory of

Biomechanics of University of Porto can provide answers. Ongoing

works to reduce the risk of injury in the diabetic foot and in the

optimization of the mobility of patients operated on the legs can lead to

results with application in gait of elderly people and in minimizing the

risk of falls.


27

Figure 1 - Sensor for 2D shear force assessment in the plantar region of patients

with diabetic neuropathy, (Patent pending).

------------------------------------------------

Mario Vaz joined the Faculty of Engineering of the University of Porto teaching

staff in 1985. Throughout his professional life took part in several research

projects in the area of inspection of structures and characterization of its

behavior under load, as well as in developing methods of inspection based on the

use of laser radiation. He was also involved in several projects of technology

transfer and expertise in various accidents involving structures. Currently his

main research interest are focused on Solid Mechanics, Holographic

interferometry, NDT of Composites, Dynamic of Materials, Biomechanics,

Experimental Mechanics, Image Processing.

Book of abstracts of the 2nd International Conference of the International Journal of Strucutral Integrity________________________________________

28

IJSI2014 Program

Program Overview


29

Technical Program

August 07th, 2014

MONDAY, 1 September 2014

MON, 09:00 - 09:30 OPENING SESSION Room Lisboa

Welcome to Participants (Conference Co-Chairs)

Welcome Address Vice-President of Regional Government

MONDAY, 24 JUNE 2013

MON, 09:30 - 10:15 PLENARY LECTURE I Room Lisboa

Challenge on Application of Titanium Alloys on Aeronautic Structures Professor Carmine Pappalettere

(Politecnico di Bari, Italy) Chair: Dr. Pedro Moreira (INEGI, Portugal)

MON, 10:15 - 11:00 PLENARY LECTURE II Room Lisboa

Full-field optical methods for measurements and monitoring of industrial structures Professor Malgorzata Kujawinska

(Warsaw University of Technology, Poland) Chair: Prof. Mário Vaz (FEUP, Portugal)

MON, 11:00 - 11:30 COFFEE-BREAK Lounge


30

MON, 11:30-13:00 Session 1 Room Lisboa

TOPIC: Processes Chair: Sérgio Tavares

Ref: Title and Author (s) Page:

#132 Friction Stir Weldbonding of Aluminum Joints Daniel F. O. Braga, Ana C. F. Silva, Lucas F.M. da Silva, P. M. G. P. Moreira

link

#136 The effect of welding direction in the fatigue life of aluminium FS welded lap joints F. F. Duarte, V. Infante, P.M.G. Moreira, M. de Freitas, P.M.S.T. de Castro

link

#112 Mechanical Fracture Behaviour of Laser Beam-Welded AA2198 Butt-Joints and Integral Structures N. Kashaev, A. Carvalho, M. Nurgaliev, S. Riekehr, N. D. Alexopoulos, A. Karanika

link

#117 Influence of the Kissing Bond Defect to the Fatigue Life in Friction Stir Welds of 2024 Aluminium Alloy Roman Růžek, Martin Kadlec, Lucie Nováková

link

#129 Influence of tool geometry and process parameters on defect formation in lap joining by friction stir welding of very thin plates C. Leitão, M.I. Costa, D.M. Rodrigues

link

#190 Shoulder design options on lap joined FSW plastics Shayan Eslami, Paulo J Tavares, P M G P Moreira

link

MON, 13:00 - 14:15 LUNCH Restaurant


31

MON Session 2A

14:15-15:30

Room Lisboa

MON Session 2B 14:15-15:30

Room Berlin

TOPIC: Materials Chair: Jaime Monteiro

TOPIC: Bio-Mechanics Chair: José Xavier

Ref: Title and Author (s) Page: Ref: Title and Author (s) Page:

#102 Combining nanocrystallisation processes with a subsequent thermomechanical processing – interfacial oxidation Michal Krzyzanowski ,Szymon Bajda, W. Mark Rainforth

link #147 Safety characterization of helmets for roller hockey goal keepers M. A. P. Vaz, Nuno V. Ramos

link

#122 Structure, electromagnetic wave absorption and mechanical behavior of carbonaceous nanofillers modified polymer composites R. Merijs Meri, J. Zicans, T. Ivanova, J. Bitenieks, P. Kuzhir, S. Maksimenko

link #148 Mechanical Behavior Characterization of a Lumbar Vertebra; With or Without Cement Reinforcement Cláudia Carneiro, Nuno Neves, Nuno Viriato, Mário Vaz

link

#123 Hydrogen influence on fatigue in a Cr-Mo steel Donka Angelova, Rozina Yordanova, Svetla Yankova, Ralitsa Pavlova

link #185 Structural integrity of a Maryland dental bridge Ivo Lopes, André Correia, Nuno Viriato Ramos, Mário Vaz, JC Reis Campos, Pedro Couto Viana

link

#126 Structure-property relationships of PC/ABS blend composites with nanoclay J. Zicans, R. Merijs Meri, R. Berzina, R. Maksimov, V. Kalkis

link #186 Comparison of mechanical behaviour between two brands of extra oral force modules LB Cavalcanti, MJ Ponces, MP Vaz, VC Pinto, MA Sampaio-Fernandes, JCR Campos

link

#152 Evaluation of nitriding process effects on cold worked AISI 304 and 316 austenitic stainless steels W. A. Monteiro, S. A. L. Pereira, J. Vatavuk

link #187 The application of epoxy paint for improved aesthetics in partial dentures’ frameworks Francisco Góis, Bruno Henriques, Pedro Gomes, Margarida Sampaio-Fernandes, Maria Helena Figueiral, Maria Helena Fernandes, Filipe Silva, João Sampaio-Fernandes

link

#191 Effect of impressions disinfection on the surface detail reproduction M Portela, P Fonseca, M Sampaio-Fernandes, Francisco Góis, MH Figueiral

link

MON, 15:30 - 16:00 COFFEE-BREAK Lounge


32

MON Session 3A

16:00-17:15 Room Lisboa

MON Session 3B 16:00-17:15

Room Berlin

TOPIC: Models Chair: Virginia Infante

TOPIC: Processes Chair: Mario Vaz


#103 Elasto-plastic analysis of structures using an Isogeometric formulation J. Ferreira, M. Seabra, M. Parente, R. Natal

link #101 Structural Assessment of Fine-scale Structures Produced by Complex Metal Forming Processing Janusz Majta, Marcin Kwiecien, Krzysztof Muszka, Paulina Graca

link

#104 Practical Applications of the SIFCM Aaron Warren

link #105 Damage tolerance improvement of laser beam welded fuselage structures via crenellations J. Lu, N. Kashaev, N. Huber

link

#124 Multi-objective Fatigue Life Optimization using Tabu Genetic Algorithms Kim C. Long, William S. Duff, John W. Labadie, Mitchell J. Stansloski, Walajabad S. Sampath, Edwin K.P. Chong

link #138 Mechanical Behavior of Friction Stir Welded Butt Joints Ana C.F. Silva, Daniel F.O. Braga, Frederico Silva Gomes, M.A.V. de Figueiredo, P.M.G.P. Moreira

link

#182 Induction of Through-Thickness Compressive Residual Stress Fields in thin Al2024-T351 Plates by Laser Shock Processing J.L. Ocaña, C. Correa, J.A. Porro, M. Díaz, L. Ruiz de Lara, D. Peral

link #141 Manufacturing and characterization of nanostructured Al-Si-Si3N4-C composites for high-wear application Malgorzata Sopicka-Lizer, Jerzy Myalski, Daniel Michalik, Tomasz Pawlik, Nathalie Valle, Agnieszka Boto-Probierz

link

#143 Development of multi-layer fibrous composites for fire resistant and sound insulating doors Fernando Cunha, Carlos Mota, Raul Fangueiro, Manuel Ferreira, Nelson Silva

link

Mon, 18:30 - 19:30 WELCOME RECEPTION IVBAM

COCKTAIL RECEPTION by courtesy of IVBAM

Institute of Madeira Wine


33

TUESDAY, 2 September 2014


TUE, 09:30 - 10:15 PLENARY LECTURE III Room Lisboa

A Deviatoric Neuber’s Rule and SWT Parameter for Fatigue Analysis Professor Daniel Kujawski

(Western Michigan University, USA) Chair: Dr. Paulo Tavares (INEGI, Portugal)

TUE, 10:15 - 11:00 PLENARY LECTURE IV Room Lisboa

The significance of the interaction of stability and damage propagation in metallic and composite panels Professor Peter Horst

(Technische Universität Braunschweig, Germany) Chair: Prof. Chris Rodopoulos (Monash Univ, Australia)

TUE, 11:00 - 11:30 COFFEE-BREAK Lounge


34

TUE Session 4A 11:30-13:00

Room Lisboa

TUE Session 4B 11:30-13:00

Room Berlin

TOPIC: Processes Chair: Peter Horst

TOPIC: Testing Chair: Malgorzata Kujawinska


#171 Cold plasma treatment of polymeric matrix composites F. Velasco, A. Bautista, S. Guzmán, M. Pantoja

link #184 Considerations on the choice of the drilled hole diameter in ESPI-HDM residual stress measurements in Ti6Al4V C. Barile, C. Casavola, G. Pappalettera, C. Pappalettere

link

#173 Modification of metallic surfaces by duplex treatments involving severe shot peening, pulsed electron beams and nitriding T. Grosdidier, Y. Samih, B. Beaussir, T. Czerwiec, S.Z. Hao, C. Dong

link #188 Experiment Research and Application on Super-Retarding Mortar Xin Feng, Xianyan Zhou

link

#174 A study on the effect of weld induced residual stresses and the influence of weld sequencing of centrifugal extractor rotating bowl using numerical simulation and experimental validation Satish Kumar Velaga, Gaurav Rajput, T. Selvaraj, B.M. Anandarao, A. Ravisankar

link #135 Characterization of orthotropic stiffness components of Pinus pinaster from heterogeneous plate bending tests W. Cruz, J. Xavier, F. Pierron, J. Morais

link

#128 Internal Expansive Reactions in Concrete Structures – Deterioration of the mechanical properties João Custódio, António Bettencourt Ribeiro

link #172 Sloshing effect on the dynamic behavior of large capacity horizontal cylindrical tank due to seismic excitation and it's qualification Sanatana Maharana, Sunil Kumar Gupta, T.Selvaraj, B.M.Ananda Rao, A.Ravisankar

link

#189 A comparison between the deformation behaviour of dissimilar AA2024‐T3/AA7050‐T7651 welds produced by Stationary Shoulder Friction Stir Welding and standard Friction Stir Welding A. Barbini, J. Carstensen, J.F. dos Santos

link #180 Fatigue cracks thermal patterns António silva, Pedro Moreira, Mário Vaz, Joaquim Gabriel

link

TUE, 13:00 - 14:15 LUNCH Restaurant


35

TUE Session 5A



Room Berlin

TOPIC: Models Chair: Carmine Pappalettere

TOPIC: Testing Chair: Daniel Kujawski


#142 Predicting the fatigue life of mechanical components using continuum damage mechanics (CDM): application to a railway axle Zoser Kalengayi T., Juan Carlos P., Cristina Castejón S., María Jesús G

link #176 Evaluation of Semi-Ellipsoidal Wall Thinning on Back Surface of Plate by Direct-Current Potential Difference Method Naoya Tada, Manabu Nohara

link

#145 Dynamic models in stress wave dispersion filtering in the Hopkinson Pressure Bar Francisco Q de Melo, Mario A P Vaz, Jaime M. Monteiro

link #113 Internal residual stresses of tungsten-CFRP hybrid laminates M. Kanerva, E. Sarlin, M. Wallin, M. Laulajainen T. Brander, O. Saarela

link

#146 Sensitivity of Material Parameters on the Fatigue Crack Growth Calculations S.M.O. Tavares, P.M.S.T. de Castro

link #130 Dynamic parameters and dissipative capacity of a pultruded FRP spatial structure Giosuè Boscato, Salvatore Russo

link

#159 Structural analysis of a cross car beam using finite element models André Pinto, S.M.O. Tavares, J. M. A. César de Sá, P.M.S.T. de Castro

link #181 Sloshing forces in a 3D liquid waste storage tank under harmonic wave excitation V.S. Sanapala, T. Selvaraj, B. M. Ananda Rao, A. Ravisankar, K.Velusamy, B.S.V. Prasad Patnaik

link

TUE, 15:30- 16:00 COFFEE-BREAK Lounge


36

TUE Session 6A



Room Berlin

TOPIC: Models Chair: Sérgio Tavares

TOPIC: Testing Chair: Paulo Tavares


#163 Application of the Strain-Based FAD to Failure Assessment of Surface Cracked Components Igor Varfolomeev, Michael Windisch, Gerben Sinnema

link #155 Evaluation of mixed-mode I+II fatigue crack propagation in steels assisted by DIC ALL Silva, J Xavier, Diogo Carvalho, AMP Jesus, AA Fernandes

link

#164 Theoretical and experimental model for the analysis of a cardan cross Eugen Avrigean

link #156 Virtual Sensors for SHM using isogeometric piezoelectric finite elements Artur Szewieczek, Christian Willberg, Michael Sinapius

link

#165 Multiscale Simulation Strategy for Low-Velocity Impact on FRP C. S. Lopes, F. Naya, C. González, P.P. Camanho

link #157 On Monitoring of Mechanical Characteristics of Hot Rolled S355J2 Steel Donka Angelova, Rozina Yordanova, Alexander Georgiev, Svetla Yankova

link

#115 Structural Deformation Measurements by Image Block Matching Algorithms Graça Almeida, Fernando Melício, José Manuel Fonseca

link #160 The use of optical scanning methods for testing of thin oxide films deposited on rough steel substrates Janusz Jaglarz

link


37

WEDNESDAY, 3 September 2014


WED, 09:30 - 10:15 PLENARY LECTURE V Room Lisboa.

Optimising Controlled Shot Peening Parameters for Optimum Fatigue Life Professor Chris Rodopoulos

(Monash University, Australia) Chair: Prof. Malgorzata Kujawinska (Warsaw Univ, Poland)

WED, 10:15 - 11:00 PLENARY LECTURE VI Room Lisboa

Structural Monitoring and Biomechanics Professor Mário Vaz

(Faculty of Engineering of University of Porto, Portugal) Chair: Prof. Daniel Kujawski (Western Michigan Univ, USA)

WED, 11:00 - 11:30 COFFEE-BREAK Lounge

WED, 11:30-13:00 Session 7 Room Lisboa

TOPIC: Testing Chair: Chris Rodopoulos

Ref: Title and Author (s) Page:

#108 System for Fuel Elements Inspection of Nuclear Research Reactor by the Sipping Method Rogerio Rivail Rodrigues, Amir Zacarias Mesquita

link

#111 Remote monitoring of an elevated water reservoir using optical fiber technology Paulo Antunes, Humberto Varum, Paulo André

link

#114 Thermal Fatigue Behaviour of Polyamides used in Intercoolers D. Faustino, V. Infante, L. Neves

link

#116 Long term monitoring of a high-speed railway bridge: thermal behavior Manuel Cuadrado, Daniel Gómez del Pulgar, Emma Moliner

link

WED, 13:00 - 14:15 LUNCH Restaurant


38

WED Session 8A

14:15-15:30

Room Lisboa

WED Session 8B 14:15-15:30

Room Berlin

TOPIC: Testing Chair: José Xavier

TOPIC: Materials Chair: Peter Horst


#119 Keying Effect During Fracture of Stainless Steel Farej Ahmed Emhmmed

link #151 Characterization of nickel alloy 600 with ultra-fine structure processed by severe plastic deformation technique (dpi) W. A. Monteiro, S. L. V. Silva, L. V. Silva, A. H. P. de Andrade, L. C. E. Silva

link

#120 Non-destructive methodology based on magnetic flux density measurement, in the reversibility domain region, to follow stainless steel embrittement Edgard M. Silva, Jorge H. R. Silva, Ana L. S. Souza, Neilor C. Santos, Josinaldo P. Leite, Mickael M. Rodrigues

link #134 The effect of size, amount and surface treatment of micro particles of cork on the toughness of a brittle epoxy A.Q. Barbosa, L.F.M. da Silva, J. Abenojar, M. Figueiredo, A. Öchsner

link

#127 Analysis of the magnetic field integrity of electric machine and construction structure Stanisław Radkowski, Szymon Gontarz, Przemysław Szulim

link #169 Corrosion performance of corrugated stainless steels in mortar partially immersed in chloride solution for 8 years A. Bautista, S.M. Alvarez, E.C. Paredes, F. Velasco

link

#137 SIF determination with Digital Image Correlation Paulo J. Tavares, Frederico Silva Gomes, P.M.G.P. Moreira

link #110 Fatigue damage evolution and life prediction for metastable austenitic steels under consideration of martensite phase transformation Huang YUAN

link

#162 Biodegradable composite thermoplastics used in interior parts of aerospace and automobile products André F. C. Vieira, Rui M. Guedes, Volnei Tita

link

WED, 15:30-16:00 COFFEE-BREAK Lounge


39

WED Session 9A

16:00-17:15

Room Lisboa

WED Session 9B 16:00-17:15

Room Berlin

TOPIC: Testing Chair: Sérgio Tavares

TOPIC: Materials Chair: Daniel Kujawski


#139 Fatigue Crack Growth Measurement Automation Tavares, Paulo J., Viriato, N.S., Moreira, P. M. G. P.

link #170 Fire resistant coatings for polymeric matrix composites F. Velasco, S. Guzmán, A. Bautista, M.A. Martínez

link

#140 Contactless defect detection using two emerging Optical Methods for NDT of composite structures - Thermography and Shearography Monteiro, J., Lopes, H., Vaz, M.A.P.

link #177 Evaluation of Advanced Materials in Aircraft Structure Martin Bugaj, Andrej Cíger

link

#144 Novel Non-Destructive Testing techniques for structural integrity F. Nascimento, T. Santos, C. C. C. R. de Carvalho, R. Miranda, L. Quintino

link #179 Electromagnetic shielding enclosure built on metallic lightweight structure for aerospace EMI protection applications - Experimental tests and numerical simulation Mihai Enache, Dan Fostea, Adina Otilia Boteanu, Cristian Puică

link

#149 Structural monitorization of windturbine Silvina Guimarães, Miguel Marques, João Rio, M. A. P. Vaz, Nuno V. Ramos, José Matos

link #183 Influence of Titanium, Niobium and Aluminium addition on microstructure and mechanical properties of Ferritic Stainless Steel welds Nabil Bensaid, Mohamed Farid Benlamnouar, Amar Boutagane

link

#161 Designing and optimization of new composite pallet Alexander Janushevskis, Anatolijs Melnikovs

link

WED, 17:15 – 17:45 CLOSING SESSION Room Lisboa

Conference Organizing Committee

WED, 19:00 - 23:00 BANQUET

CONFERENCE BANQUET courtesy of Madeira Government

Restaurante Adega da Quinta, Estreito de Câmara de Lobos

Book of abstracts of the 2nd International Conference of the International Journal of Strucutral Integrity______________________

40

Abstracts


41

Session 1

MON, 11:30-13:00

Room Lisboa

TOPIC: Processes

Chair: Sérgio Tavares


42

#132

Friction Stir Weldbonding of Aluminum Joints

Daniel F.O. Braga1, Ana C.F. Silva

1, Lucas F.M. da Silva

2, P.M.G.P. Moreira

1

1 Institute of Mechanical Engineering and Industrial Management (INEGI), University of Porto,

Porto, Portugal

2Instituto de Engenharia Mecânica (IDMEC), Porto, Portugal

Abstract Replacement of conventional steel alloys for aluminum alloys has been an emerging

trend in metallic structures. Although the use of these alloys has previously been restrained by

production difficulties associated with their poor welding properties, friction stir welding and

adhesive bonding allowed for a larger flexibility in lightweight structural design. In this

preliminary work an innovative joining process combining these two technologies was studied.

Static properties of the obtained joints were accessed, and compared to joints obtained with

adhesive bonding and friction stir welding.

Friction stir welding (FSW) is a revolutionary joining method that allowed welding of

previously unweldable alloys with excellent characteristics, and has an enormous potential for

application in a large array of industries. Even though friction stir welding presents several

advantages over other welding techniques when regarding joining of aluminum alloys, it also

presents its share of challenges. The occurrence of fatigue cracks in these joints makes them

especially susceptible to this phenomenon, even more when the welding parameters used are not

optimized. Corrosion is also a concern in FSW, as the metallurgical modifications occurred during

the joining process may accelerate this deteriorating phenomenon.

The combination of FSW with adhesive bonding (AB), forming friction stir weldbonding may

present itself as a solution for these concerns. The development of this new joining technology

aims at incorporating properties and characteristics of both joining technologies. FSW is able to

produce joints with very high static strength, while the adhesive from AB will not only allow

improved vibration damping and fatigue strength improvement but may also serve double duty as

a sealant, isolating the weld from the environment.

In this presentation early studies on the development of the friction stir weldbonding technique

will be shown and the technique potential will be discussed.


43

#136

The effect of welding direction in the fatigue life of aluminium fs

welded lap joints

F.F. Duarte1, V. Infante2, P.M.G.P. Moreira3, M. de Freitas2, P.M.S.T. de Castro3

1INEGI, Campus da FEUP, Rua Dr. Roberto Frias, 400 4200-465 Porto, Portugal

2IST, Av. Rovisco Pais, 1049-001 Lisboa, Portugal

3FEUP, Rua Dr. Roberto Frias 4200-465 Porto, Portugal

ABSTRACT

Friction Strir (FS) welding lap joints of aluminium alloy AA6082-T6 were joined using to distinct

configurations. The main objective of this work is to study the effect of the welding line direction

in the fatigue life of the specimens. For that purpose, the welding was performed in order to

establish two distinct loading situations, one with the welding line parallel to the loading direction

and the other with welding line perpendicular to the loading direction. Fatigue tests were

performed under a constant amplitude load and a stress ratio of R = 0.1. As shown in previous

studies, the hook defect plays a decisive role in the mechanical behavior of the joint, in particular,

when submitted to fatigue load cycles. The specimen with the welding line parallel to the loading

direction showed a superior fatigue behavior, approximately, two times more efficient than the

perpendicular configuration. Two finite element models were created in order to validate the

behavior of the welded zone and, in particular, to compare the hook formation influence between

both configurations.

KEY WORDS: Friction Stir Welding, Lap joint, Welding direction, Hook defect, Fatigue

behavior.


44

#112

Mechanical Fracture Behaviour of Laser Beam-Welded

AA2198 Butt-Joints and Integral Structures

1N. Kashaev,

1A. Carvalho,

1M. Nurgaliev,

1S. Riekehr,

2N. D. Alexopoulos,

3A. Karanika

1Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht,

Max-Planck-Str. 1, 21502 Geesthacht, Germany. Contact: [email protected]

2Department of Financial Engineering, University of the Aegean, 41 Kountouriotou Str., 82100

Chios, Greece

3Research and Product Design, Hellenic Aerospace Industry S.A., P.O. Box 23, 32009

Schimatari, Greece

Abstract

To meet the future demands of the aerospace industry with respect to safety, productivity,

weight, and cost, new materials and joining concepts have being developed. Recent developments

in the metallurgical field now make it possible to use laser-weldable Al-alloys of the 2xxx series

such as AA2198 with a high structural efficiency index due to their high strength and low density.

AA2198 holds the promise of providing a breakthrough response to the challenges of lightweight

design in aircraft applications. Laser beam welding as an efficient joining technology for fuselage

structures is already established in the aircraft industry for lower fuselage panels because the

welded panels provide a higher buckling strength and lower weight compared with the classical

riveted designs. The key factor for the application of laser-welded AA2198 structures is the

availability of reliable data for the assessment of their damage tolerance behaviour. In the research

presented, the mechanical properties with regard to quasi-static tensile and the fracture toughness

(R-curves) of laser beam–welded AA2198 butt-joints in T3 and T8 temper were investigated. In

the next step a systematic analysis to clarify the deformation and fracture behaviour of the laser

beam-welded AA2198 four-stringer panels is provided. The mechanical test results were also

compared against the respective of conventional AA2024 and AA6013, in order to assess the

degree of improvement by exploiting the new material/process.

a) b) c)

Figure 1 a) Metallographic cross section of a butt-joint, b) metallographic cross-section of a T joint, and c)

welded demonstrator panel from aluminum alloy AA2198 (AA2198T3 as skin and AA2198T8 as stringer).

mailto:[email protected]


45

#117

Influence of the Kissing Bond Defect to the Fatigue Life in Friction Stir

Welds of 2024 Aluminium Alloy

Roman Růžek1, Martin Kadlec

1, Lucie Nováková

1

1Aerospace Research and Test Establishment, Beranovych 130, 199 05 Prague, Czech Republic.

Email: [email protected]

Abstract

Friction stir welding (FSW) has advantages over conventional welding in terms of economic,

environmental and safety. This technology contributes to increased joining speed, higher stress

tolerance, better reproducibility and longer service life when compared to common riveting

methods used for aerospace structures. So far, the FSW is restricted only to non-safety critical

aerospace components, because there is no reliable method for detecting kissing bonds which

have significant effect on fatigue life.

In order to evaluate static and dynamic loading effect, a set of samples with different

thicknesses, which are representative of aerospace components, was manufactured and

categorized into: FSW without any defects and FSW with the kissing bond defects.

The effects of the KB defects on tensile and fatigue properties of 2024 T3 friction stir welds

have been quantitatively evaluated with respect to a reference weld without any flaws. Various

KB defects were investigated with the aim of evaluation which defect geometry has no influence

to the fatigue life of joined 6 mm thickness sheets. A critical value for KB geometry seems to be

0.3 mm in depth considering influence on fatigue life for investigated configurations.

The FSW can be interpreted as a stress concentration. Therefore, the basic material with stress

concentration equal to 1 and 2.6 was also evaluated. These values are typical for structures without

concentrators and for regular area of a riveted panel structure. The definition of this stress

concentration equivalent can be very helpful for design purposes and application.



46

#129

Influence of tool geometry and process parameters on defect formation

in lap joining by friction stir welding of very thin plates

C. Leitão1, M.I. Costa

1, D.M. Rodrigues

1

1CEMUC, Department of Mechanical Engineering, University of Coimbra

Abstract: One of the main concerns in lap joining by friction stir welding (FSW) of any type

of plates is the formation of an important defect, such as that exemplified in Figure 1, mainly at

the advancing side of the welds. Due to its particular morphology, this defect, reported in most of

the studies in literature on lap joining by FSW, is usually called hook, and is attributed to the

particular material flow mechanisms and thermo-mechanical conditions developed during

welding. Naturally, the presence of this small discontinuity has a negative effect on welds

strength, which is particularly harmful in lap joining of very thin plates.

In current work several tools and welding parameters were tested in order to simultaneously

minimize the occurrence of this defect and improve welding productivity, for a selected range of

ferrous and non-ferrous alloys. The mechanical characterization of the welds included not only

performing tensile-shear tests, but also fatigue analysis. It was found that by an accurate choice

of process parameters and toll geometry, it is possible to minimize or even suppress the hook

defect. The microstructural characterization of the welds, as well as the mechanical tests

performed, enabled to determine a strong influence of base materials properties on the selection

of the most suitable friction stir lap welding conditions.

Figure 1 – Hook defect.


47

#190

Shoulder Design Options for FSW Lap Joints of Plastic Sheets

Shayan Eslami*, Paulo J. Tavares, P.M.G.P. Moreira

1INEGI, Instituto de Engenharia Mecânica e Gestão Industrial, Rua Dr. Roberto Frias 400,

Porto, Portugal, *email: [email protected]

Abstract

Friction Stir Welding (FSW) method can be considered as one the most significant joining

methods, which has developed considerably in the last decade. FSW is mostly used for joining

metals and lightweight alloys that can be difficult to weld by traditional techniques. However, in

recent years, FSW of plastic materials has taken its initial steps with the purpose of becoming

widespread in different industrial applications due to its benefits over the conventional welding

methods. Nevertheless, as all new techniques, FSW of plastics needs technological development

in order to be considered as a major asset for new industrial applications.

The main difficulty for FSW of plastics is the lack of frictional heat generated through contact

between the rotational tool and the base material. This applied friction should generate the

adequate heat in order to increase the material temperature near its melting point. For FSW of

Aluminum alloys, this task is implemented by the shoulder touching the surface, which generates

enough heat to stir the material together. Therefore, the shoulder has an essential role in this

process and could be one of the main parameters that plays a considerable effect on the weld

strength, as well as welding surface. However, it is worth mentioning that the good welding

surface is normally followed by good joint quality.

The previous FSW studies suffer from a lack of proper investigation for joining the plastic

materials, especially for lap joining of dissimilar plastics. With this in mind, the present work

focuses on the effect of different shoulder designs for the lap joints of dissimilar plastics which

in this experiment are Polystyrene and Polypropylene. Furthermore, this case study demonstrates

the advantages of using stationary shoulder for welding the plastic materials, as well as

eliminating the flaws in this path with the intention of achieving sound welds.


48

Session 2A

MON, 14:15-15:30

Room Lisboa

TOPIC: Materials

Chair: Jaime Monteiro


49

#102

Combining nanocrystallisation processes with a subsequent

thermomechanical processing – interfacial oxidation

Michal Krzyzanowski*, Szymon Bajda*, W. Mark Rainforth**

* AGH University of Science and Technology, Faculty of Metals Engineering and Industrial

Computer Science, Mickewicza 30, Krakow 30-059, Poland

** The University of Science and Technology, Department of Materials Science and

Engineering, Mappin Street, Sheffield, S1 3JD, UK

Abstract Impurities deposited on the surface of the materials cause bonding imperfections due

to interfacial oxidation during the duplex techniques based on combining nanocrystallisation

with a subsequent co-rolling in order to produce multilayered bulk structures with improved

mechanical properties. It has been shown that the interface oxidation occurring during duplex

processes can influence the microstructure development around the interfaces depending on

whether the oxide scale is a continuous layer or a layer of discontinuous oxide clusters with

heterogeneous thicknesses. Formation of oxide scale related defects at the interfaces and

formation of shear zones within the affected areas around the interfaces has been

demonstrated numerically. The through-thickness shear zones within the material can link the

scale related defects on both the upper and lower interfaces.

Acknowledgement

The financial support of Polish National Science Centre, research grant:

DEC-2013/09/B/ST8/00141, is highly appreciated.


50

#122

Structure, electromagnetic wave absorption and mechanical behavior

of carbonaceous nanofillers modified polymer composites

R. Merijs Meri1, J. Zicans

1, T. Ivanova

1, J. Bitenieks

1, P.Kuzhir

2, S. Maksimenko

2

1Riga Technical University, Institute of Polymer Materials, Paula Valdena str. 3, Riga, LV

1048, Latvia, [email protected]

2Belarus State University, Institute of Nuclear Problems, Minsk, Belarus

Abstract Polymer-carbonaceous nanofiller composites are recognized are perspective

materials for broad range of engineering applications, serving building, automotive and aerospace

industries. Efficiency of carbonaceous nanofillers in tailoring electromagnetic, electrical,

mechanical and thermal performance of polymer materials according to the customer needs are

largely dependent on the interplay of the ingredients of the composites in the micro- and

nanolevels. Consequently profound attention should be paid to the processing regime-structure-

property relationships at the development of the carbonaceous nanofiller modified polymer

composites.

The current research is devoted to evaluation of the modification potential of styrene acrylate

copolymer (SAC), widely used material in coating and adhesive industry, by means of structurally

diverse carbonaceous nanofillers: almost isotropic onion like carbons (OLC), as well as neat and

organically modified highly anisometric multiwall carbon nanotubes (MWCNT and MWCNT-

COOH, respectively). The extent of the nanofiller distribution in the SAC matrix, and hence

expoitation properties of the polymer nanocomposites, has been tailored by means of addition of

appropriate amounts of specific surfactants. The content of the carbonaceous nanofillers in the

polymer matrix was varied within the broad range between 0 and10 wt.%. Zeta potential

measurements of OLC, MWCNT and MWCNT-COOH dispersions in water and SAC with or

without surfactants have been performed to develop the technology of manufacturing of

carbonaceous nanofillers containing polymer composites. Performance of the obtained

nanocomposites have been characterized by using voltage standing wave ratio (VSWR) and

transmission loss meter, broadband dielectric spectrometer (DES), differential scanning

calorimeter (DSC) and dynamic mechanical thermal analyzer (DMTA).

Elastic modulus, electrical conductivity and electromagnetic radiation absorption of the

investigated SAC nanocomposites increase along with rising carbonaceous nanofiller content.

The effect of the addition of anisometric carbonaceous nanofillers on the mechanical properties

of the composite is higher than that of the addition of OLCs. In all the cases, however, shift of

glass transition temperature of SAC towards higher temperatures is observed testifying about

decreased flexibility of the polymer macromolecules in the proximity of the nanofiller particles.

Higher electrical conductivity of the OLCs containing nanocomposites is explained with the fact

that reasonable agglomeration of the nanofiller can promote the development of electrically



51

conductive network. It has been also observed that efficiency of the absorption of electromagnetic

radiation depends on the development of conductive network within the SAC matrix.


52

#123

Hydrogen influence on fatigue in a Cr-Mo steel

Donka Angelova, Rozina Yordanova, Svetla Yankova, Ralitsa Pavlova

University of Chemical Technology and Metallurgy – Sofia, 8 St. Kliment Ohridski, Blvd., 1756

Sofia, Bulgaria, [email protected]

Abstract Fuel cell vehicles and stationary fuel cell systems, their equipment and infrastructure

need components of materials subjected to high-pressure hydrogen under fatigue conditions. This

makes very important a complete study concerning hydrogen influence on materials, candidates

for usage in hydrogen technologies. Murakami has investigated tension-compression fatigue in

uncharged and hydrogen charged specimens of Cr-Mo steel JIS SCM435 under different test

frequencies from the interval [0.2, 20] Hz, [1]. He found an effect of increasing crack growth rates

in the hydrogen charged specimens with decreasing of frequencies, which is shown in the

presentation "Crack growth rate, da/dN - Stress intensity factor range, ΔK, Fig. 1.

Based upon experimental short fatigue crack growth data of Murakami, new crack growth

equations have been derived in an attempt to describe more precisely short fatigue crack growth

behaviour that separates the different regimes of crack propagation. Although in Murakami

experiments the short fatigue cracks start from a little artificial hole, they experienced the three

regimes of short crack growth: those of short fatigue crack, physically small fatigue crack, and

long fatigue crack. The intervals of physically small fatigue crack propagation, in terms of da/dN,

decrease for the hydrogen charged specimens and smaller test frequencies; the intervals are shown

by limitation arrows in Fig. 1.

SCM435

1,0E-10

1,0E-09

1,0E-08

1,0E-07

1,0E-06

1,0E-05

1,0E+01 1,0E+02Stress intensity factor range, ΔK (MPa√m)

Cra

ck

gro

wth

ra

te d

a/d

N (

m/c

yc

le)

Uncharged Constant frequency f = 20 Hz

Charged Constant frequency f = 20 Hz

Charged Constant frequency f = 2 Hz

Charged Constant frequency f = 0.2 Hz

Series13

Series14

Series15

Series16

Series17

Series18

Series19

Series20

Power (Uncharged Constant frequency f

= 20 Hz)Log. (Charged Constant frequency f = 0.2

Hz)Log. (Charged Constant frequency f = 2

Hz)Log. (Charged Constant frequency f = 20

Hz)

0,2 Hz

2 Hz

20 Hz


53

Figure 1 - Tension-compression fatigue in JIS SCM435 steel under test frequencies from the

interval [0.2, 20] Hz

References

[1] Murakami Y., “Effect of Hydrogen on Fatigue Crack Growth of Metals”, 17th European

Conference on Fracture, 2-5 September, 2008, Brno, Czech Republic, pp. 25-42, 2008


54

#126

Structure-property relationships of PC/ABS blend composites with

nanoclay

J. Zicans1, R. Merijs Meri

1, R. Berzina

1, R. Maksimov

2, V. Kalkis

3

1Riga Technical University Institute of Polymer Materials, Paula Valdena str. 3, Riga, LV 1048,

Latvia, [email protected]

2University of Latvia, Institute of Polymer Mechanics, Riga, Latvia

3University of Latvia, Faculty of Chemistry, Riga, Latvia

Abstract The concept of Key Enabling Technologies (KET) is envisaged to be the main

driving force for development of future goods and services. One of the building blocks of KET

in nanotechnology is development of recyclable polymer nanocomposites with enhanced stress-

strain, barrier, adhesion, rheological and other properties for broad range applications. This aim

is largely achievable by the control of exploitation properties of polymer nanocomposites by

manipulations in the structural level. Hence we focus on the investigations of structure-property

relationships of recyclable engineering polymer nanocomposites, as well as prediction of it

properties by using structure dependent mathematical models.

The nanocomposites have been developed on the bases of polycarbonate (PC) blend with 10

wt. % of acrylonitrile-butadiene-styrene terpolymer (ABS). Unmodified (MMT) and organically

modified (OMMT) nanoclays in the concentration range between 0 and 2 wt. % have been

introduced in the PC/ABS matrix by using twin-screw extrusion process. Especial attention has

been devoted to optimization of extrusion process of the investigated nanocmposites. Structural,

calorimetric, as well as elastic characteristics have been investigated. The approach to predict the

properties of the investigated nanocomposites by using micromechanical models has been

proposed.

As a result set of optimized technological parameters, such as profile of the extruder

temperatures as well as screws rotation speed, have been proposed for manufacturing of

intercalated PC/ABS blend nanocomposites. By evaluating the effect of nanostructured clay

modifier on the tensile stress-strain characteristics of PC/10%ABS blend, it has been revealed that

greater modulus and strength increment is observed in the case of the nanocomposites, containing

aromatic organomodifier treated clay (Ar-OMMT). Ar-OMMT addition to PC/ABS matrix

considerably improved also dynamic modulus of the nanocomposites. Besides it along with

increased modulus of elasticity and strength glass transition temperature of the material increase,

testifying about stiffening of the polymer macromolecules in the presence of Ar-OMMT. It has

been concluded that optimal nanofiller content for the investigated PC/10%ABS blend is 1.5

wt.%. The experimental results have been also compared with the results of micromechanical

modelling and the best compliance has been found for the nanocomposites with lower clay

contents in the PC/ABS matrix.



55


56

#152

Evaluation of nitriding process effects on cold worked AISI 304 and

316 austenitic stainless steels

W.A. Monteiro 1,3, S.A.L. Pereira 1,2, J. Vatavuk 3

1 Institute of Energetic and Nuclear Researches, IPEN, [email protected]

2 MAHLE Metal Leve S/A, Jundiaí / São Paulo, SP

3 Presbyterian Mackenzie University

The nitriding behavior of austenitic stainless steels (AISI 304 and 316) was studied by different

cold work degree before nitriding processes. The microstructure, thickness, microhardness and

chemical micro-composition were evaluated through optical microscopy, microhardness,

scanning electron microscopy techniques (WDS microanalysis). Through of them were observed

that previous plastic deformations do not influence expressively on layer thickness. In addition,

two different layers can be identified as resulted of the nitriding, a formed of austenitic matrix

expanded by nitrogen atoms and another thinner just below expanded by carbon atoms.

Key Words: Nitriding, Cold Working, Expanded Austenite.


57

Session 2B

MON, 14:15-15:30

Room Berlin

TOPIC: Bio-Mechanics

Chair: José Xavier


58

#147

Safety assessment of helmets for roller hockey goal keepers

Mário A.P. Vaz1,2,3

, Nuno Viriato Ramos2,3

1FEUP, Rua Dr. Roberto Frias, s/n, 4200-465, Porto, Portugal; [email protected]

2INEGI, Rua Dr. Roberto Frias, 400, 4200-465, Porto, Portugal; [email protected]

3LABIOMEP, Rua Dr. Plácido Costa, 91, 4200-450, Porto, Portugal

Abstract The purpose of this study, part of a wide research project, was to investigate the head

protection provided by a roller hockey goalkeeper helmet. An experimental setup was

implemented to assess how these protectors can decrease overall head acceleration and prevent

injuries for the goalkeepers regarding the deformation of the helmet/face shield during blunt

impacts. The most widely used helmet with a standard polycarbonate face shield was selected for

this study. To repeatedly generate controlled impacts of the ball a special gas gun was designed

allowing shots up to 120 km/h with the helmet/face shield. A sports handheld radar gun was used

to evaluate the terminal velocity of the ball. Structured illumination and image processing

algorithms allow 3D data extraction from the high speed video recordings of the impacts. The

structured light fields were computer generated and projected through a conventional video

projector. A high-speed video camera allows high sampling recordings of the helmet/face shield

deformation during impacts. The data obtained showed that the structural behavior of the

helmet/face shield is very different from other helmets, for example, motorcycle helmets, bicycle

helmets, etc. This study shows a high risk of temporomandibular injuries due to the direct support

of the face shield on the chin of the goalkeeper. Further experiments are planned to help

redesigning this kind of helmets and reduce the risk of injuries.

Figure 1 – Roller hockey helmet/face shield with structured illumination




59

#148

Mechanical Behavior Characterization of a Lumbar Vertebra; With or

Without Cement Reinforcement

Cláudia Carneiro1, Nuno Neves

2, Nuno Viriato Ramos

3, Mário A.P. Vaz

3

1Faculdade de Engenharia da Universidade do Porto, Rua Dr Roberto Frias,

4200-465 Porto, Portugal, [email protected]

2 Faculdade de Medicina da Universidade do Porto, Al. Prof. Hernâni Monteiro, 4200 - 319

Porto, Portugal, [email protected]

3 Laboratório de Ótica e Mecânica Experimental-INEGI, Campus da Faculdade de Engenharia

da Universidade do Porto, Rua Dr Roberto Frias,4200-465 Porto, Portugal,

[email protected] ; [email protected]

Abstract Vertebral compression fractures are one of the most frequent clinical outcomes from

osteoporosis and a major issue in spinal stability. Kyphoplasty is a surgical procedure for

stabilizing or preventing those fractures to occur and the only treatment option to attempt to

restore the original height of the vertebra. The efficiency of this technique in recovering the

mechanical strength of a vertebra might depend on bone cement type, the shape and volume of

the cement reinforcement and on the surgical approach. PMMA can be excessively rigid and

doesn´t promote bone regrowth. New solutions should be explored in order to obtain appropriate

mechanical strength and bone regeneration. This work aims to characterize the biomechanical

behavior of a lumbar vertebra in healthy, osteoporotic and various prophylactic-augmented

conditions in order to investigate the influence of the aforementioned parameters in mechanical

strength restitution. A 3D model of a lumbar vertebra was developed from a CT scan. The

mechanical properties specified for the cortical shell, trabecular bone, endplates, posterior

elements and bone cement were collected from the literature. A compressive force of 800 N was

applied to the superior endplate while the inferior one was entirely constrained. Osteoporosis was

simulated reducing bone Young modulus. One oblate-spheroid or two prolate-spheroids making

10 or 20% of the vertebral body volume correspond to unipedicular or bipedicular filling,

respectively. A physical model of the vertebra was obtained by rapid prototyping for numerical

validation with electronic speckle pattern interferometry. None of the PMMA prophylactic

augmentations fully reestablished the biomechanical behavior of a healthy vertebra. This can be

related to the excessive rigidity of the acrylic cement in comparison to that of trabecular bone.

Still, so far, the results suggest 20% PMMA unipedicular filling to be the best treatment option

for this case study, exhibiting the most significant reduction on the maximum von Mises stress

and total displacement in comparison to the osteoporotic condition. This model proved to be a

very useful tool for predicting changes on the biomechanical behavior a lumbar vertebra,

providing guidelines for physicians to improve the efficiency of these treatments, thus preventing

undesired clinical outcomes from osteoporosis to occur.






60


61

#185

Structural integrity of a Maryland dental bridge

Ivo Lopes1, André Correia

1,2, Nuno Viriato Ramos

2, Mário A.P. Vaz

2, J.C. Reis Campos

1,2,

Pedro Couto Viana2

1Faculty of Dental Medicine of the University of Porto, Rua Dr. Manuel Pereira da Silva 4200-

393 Porto, Portugal. [email protected] ; [email protected] ; [email protected]

2INEGI – Institute of Mechanical Engineering and Related Research. Campus da FEUP, Rua

Dr. Roberto Frias 400, 4200-465 Porto, Portugal. [email protected] ; [email protected]

Abstract Maryland dental bridges were developed in the ’70 of the last XX century. These

are prosthetic rehabilitations build with a middle pontic and two lateral wings that are bonded to

tooth structures. However, lack of structural integrity did not allow the use of these prosthetic

rehabilitations for a medium-long time. Due to the evolution of dental materials, mainly dental

adhesives/cements and ceramic frameworks, these bridges are being reintroduced in the dental

clinical practice. Although, there’s a lack of research and clinical papers on the scientific literature

that supports this feature. In this way, we’ve designed a methodological approach to do a

mechanical analysis of these dental bridges in order to contribute with evidence that supports its

clinical application. By importing a 3D design from a Maryland bridge developed in a dental

CAD-CAM software, we have built a mesh (Ansys 15.0; 39998 tetrahedral elements and 23552

nodes) that allowed us to apply the finite element method in order to do a numerical analysis of

its mechanical features. The loads that were applied resembled masticatory loads, with a vertical

and oblique direction. Our results revealed higher von Mises stresses in the connector’s areas of

the Maryland bridge, where the pontic element unifies with the wings that is bonded to the

adjacent tooth, that may be critical depending on the dental ceramic that is used in this bridges.

Geometrical optimization procedures were then developed to reduce the stress in these areas.




mailto:[email protected]%20;%[email protected]


62

Figure 1 – Finite element method applied to a Maryland dental bridge in upper incisors.

(Highest von Mises stress pointed out with a red arrow)


63

#186

Comparison of mechanical behaviour between two brands of extra oral

force modules

L.B. Cavalcanti, Faculty of Dental Medicine of University of Porto (FMDUP),

[email protected];

M.J. Ponces, FMDUP, [email protected];

Mário A.P. Vaz, INEGI, Faculty of Engeneering of University of Porto (FEUP)

[email protected];

V.C. Pinto, INEGI, FEUP, [email protected];

M.A. Sampaio-Fernandes, FMDUP;

J.C. Reis Campos, FMDUP.

Asbtract

INTRODUCTION: In daily orthodontic practice, the use of extra oral force traction is one of the

most reliable methods used during active treatment, particularly in growing patients. It represents

an instrument for attaining extra anchorage and it can also be used for orthodontic or orthopaedic

purposes. In order to select the most adequate appliance for patient treatment, it is critical to

consider the quality of the force system delivery, not only in terms of mechanical features but also

in stability over treatment time.

OBJECTIVES: This study intended to compare two distinct extra oral force delivery systems

through the analysis of the coil spring and the enclosure material components. The two selected

brands present very different commercial prices and the assessment of data may validate the

choice between the two options tested.

MATERIALS AND METHODS: This in vitro study involved 12 extra oral force modules

submitted to tensile and short-term fatigue tests. The specimens were equally divided into two

groups according to respective brands, Ormco® (California, USA) and Ceosa® (Madrid, Spain).

RESULTS: Both groups presented very similar mechanical behaviour. However, the rigidity

presented by Ormco®’s modules was slightly higher. The short-term fatigue tests showed that

there was no accumulated strain in any of the samples for the number of cycles applied. These

results were inconclusive, since it would have been necessary to perform a superior number of

cycles to analyse in detail the deformation endured by the specimens. The results from the



64

constant load tension test showed a constancy of module delivered force, even for a superior

number of hours than the usual duration of appliance use.

CONCLUSIONS: The studied devices have a well-known and predictable mechanical

performance, since they are produced under strict regulations and quality control. The price

discrepancy may be justified by the safety mechanism presented by one of the brands, which

greatly reduce the risk of injuries to the patient. Nonetheless, the performed tests allowed

concluding that both devices are mechanically trustable.

CLINICAL IMPLICATIONS: Although being identical the mechanical behaviour of extra oral

appliances, the clinical results may considerably differ. The patient’s individual features and

treatment compliance can significantly influence the outcome. For this reason, it is important to

be able to rely on the mechanical behaviour of devices, in order to guarantee perfectly known

force application.


65

#187

The application of epoxy paint for improved aesthetics in partial

dentures’ frameworks

Francisco Góis1, Bruno Henriques

4, Pedro Gomes

3, Margarida Sampaio-Fernandes

2,

Maria Helena Figueiral2, Maria Helena Fernandes

3, Filipe Silva

4, João Sampaio-

Fernandes2

1Faculty of Dental Medicine, University of Porto, Rua Dr. Manuel Pereira da Silva, 4200-393

Port, Portugal, [email protected]

2Faculty of Dental Medicine, University of Porto, Portugal

3Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, University of

Porto, Portugal

4Mechanical Engineering Department, University of Minho, Portugal

Abstract Removable partial dentures (RPDs) are still widely used in patients requiring oral

rehabilitation. Mastication and aesthetics should be considered in the treatment plan involving a

removable prosthesis.

Despite technological advances and the discovery of new materials titanium, cobalt-chromium

and gold alloys remain the most used and indicated frameworks in RPDs. However, these

frameworks have an unpleasant metallic luster that greatly compromises the aesthetic of the

rehabilitation. This is particular relevant in the extracoronal direct retainers, like clasps. Despite

their function of retention they are also used for fixation and stabilization.

Previous approaches on aesthetic covering of metal structures of RPDs and on the

development of valid alternatives have generally failed due to deficient esthetics or complete or

cohesive (chipping and cracks) fracture. It is still lacking a valid alternative that allows a

functional and long lasting aesthetic application, without inducing fragilities on the frameworks’

structure and at the same time being biocompatible.

In this work, we report the alternative of coating the framework with epoxy powder paint, used

on metallic industrial machines and equipment. It presents optimal and unique features in terms

of physical strength and aesthetics. We aim to describe the coating of a cobalt-chromium alloy

(generally used in RPDs structures) with epoxy powder paint. Preliminary biocompatibility in

vitro assays showed an adequate cell response with human fibroblasts cells. The mechanical tests

also revealed promissory results for a future clinical application. Nonetheless, further tests should

be conducted in order to predict the validity and the safely use of epoxy paint in the metal

framework of RPDs.


66

#191

Effect of impressions disinfection on the surface detail reproduction

M Portela1, P Fonseca

2, M Sampaio-Fernandes

2, Francisco Góis

2, MH Figueiral

2

1 Faculty of Dental Medicine of Oporto University, Rua Dr. Manuel Pereira da Silva, 4200-393

Porto PORTUGAL, [email protected]

2 Faculty of Dental Medicine of Oporto University

Abstract

Introduction: In dental medicine, impressions can be the cause of cross-infection between the

clinic and the laboratory. Thus it is essential to use an effective method of disinfection, which

does not alter the reproductive capacity of the surface detail of the impression materials and that

is compatible with gypsum used.

Aims: The main aims of this study are: 1 – to evaluate the surface detail reproduction capability

of alginate and silicone impressions; 2 – to evaluate the impressions surface after disinfection

with water, sodium hypochlorite or glutaraldehyde; 3 – to evaluate the compatibility of

impressions before and after disinfection with gypsum (type III and type IV).

Material and Methods: For the tests performed we used the device recommended by the

specification nº 19 of American National Standards Institute/American Dental Association and

the rule ISO 1563:1990.

Under standardized conditions, 160 impressions were made, 80 with an irreversible

hydrocolloid (alginate) and 80 with an elastomer. The impressions which were not disinfected

were used as controls and the remainder ones were passed through running water, or sprayed with

sodium hypochlorite 0.525%, or glutaraldehyde 2%.

All impressions and the gypsum casts (type III and IV) resulting was classified according with

a scale of 1 to 4 as proposed by Owen.

Statistical analysis was performed using SPSS 21 software and the nonparametric Wilcoxon

test with a statistical significance threshold of p <0.05.

Results: Regardless of the disinfection product used, the alginate impressions have a higher

surface roughness.

When the disinfectants are comparing, areas with greater detail are observed in samples from

impressions disinfected with glutaraldehyde.

In general, the gypsum type IV exhibits a greater surface roughness than the gypsum type III.

Conclusion: According to the results obtained, and whenever possible, the authors can advise

the use of an elastomeric material for dental impressions, the disinfection with glutaraldehyde and

the use of type III gypsum to obtain the cast.


67

Session 3A

MON, 16:00-17:15

Room Lisboa

TOPIC: Models

Chair: Virginia Infante


68

#103

Elasto-plastic analysis of structures using an Isogeometric formulation

J. Ferreira1, M. Seabra

2, M. Parente

1, R. Natal

1

1 IDMEC – Pólo FEUP, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal;

[email protected]; [email protected]; [email protected];

Abstract Numerical simulation often involves using the Finite Element Method (FEM) where the

geometry model, derived from CAD systems, usually suffer a reparameterization of the CAD

geometry by piecewise low order polynomials. This information transfer between models suitable

for design (CAD) and analysis (FEM) introduces significant approximation errors and entails a

amount of man-hours to generate a suitable finite element mesh [1].

In order to create industrial metal parts suitable for the imposed tasks, in which meet the

geometrical and mechanical requirements combined with reduced manufacturing costs, requires

a continuous evolution of assistive technology in order to innovate and optimize the different

stages of the production processes. In this work it is intended to contribute to the analysis of

forming processes and pipeline applications by discussing the use of an isogeometric approach

into a finite element pre- developed models.

Thus, this work makes a study of how ductile materials behave when subjected to monotonic and

cyclic mechanical loads. Isogeometric models with a small and large strains formulations,

plasticity with isotropic hardening and plasticity with kinematic hardening are developed. Also,

an introduction to a Lemaitre-based damage model is designed [2,3]. The Bauschinger effect, the

mesh dependence, and the differences between the developed small and finite strain models are

evaluated by comparison with the finite element typical discretization models. The isogeometric

discretization was performed taking the advantages of the symbolic and algebraic interface of the

AceGen software [4].

REFERENCES:

[1] T. Hughes, J. Cottrell, and Y. Bazilevs, “Isogeometric analysis: Cad, finite elements,

nurbs, exact geometry and mesh refinement,” Computer Methods in Applied Mechanics and

Engineering, vol. 194, no. 39 – 41, pp. 4135 – 4195, 2005.

[2] J. Lemaitre, A course on damage mechanics. Springer Verlag, 1996.

[3] M. Wallin, M. Ristinmaa, and N. S. Ottosen, “Kinematic hardening in large strain

plasticity,” European Journal of Mechanics - A/Solids, vol. 22, pp. 341–356, May 2003.

[4] J. Korelc, “Multi-language and multi-environment generation of nonlinear finite element

codes,” Engineering with computers, 2002.





69

#104

Practical Applications of the SIFCM

Aaron Warren1

1Jacobs Australia,

Level 7-8, 10 Hobart Place, Canberra, Australia

[email protected]

Abstract

The purpose of this paper is to discuss the practical applications of the Structural Integrity

Failure Causation Model simulation (SIFCMsim). The SIFCMsim provides a means of

simulating structural integrity and has been specifically developed for composite structures.

The SIFCMsim is presented and two practical applications are investigated: (1) criteria for

smart material damage detection and (2) structural integrity criteria for composite structures.

(1) - A potential means of negating the vulnerability of composite structural integrity to impact

damage is the use of smart materials to detect impact damage as it occurs. The SIFCMsim

provides a means of determining the detection performance requirements of the smart materials

to ensure that structural integrity is maintained.

(2) - The SIFCMsim is based on monitoring residual strength of a structure. It is proposed that a

structural integrity framework for composite structures can be established based on residual

strength with the specific criteria characterized via modeling using the SIFCMsim.

This paper will identify the relevant parameters for each application which can be characterized

using the SIFCMsim, describe how the parameters can be determined, provide example values

of the parameters and identify future work.

Keywords: Composites, structural integrity, simulation.

Article Classification: Technical Paper


70

#124

Multi-objective Fatigue Life Optimization using Tabu Genetic

Algorithms

Kim C. Long a, William S. Duff b, John W. Labadiec,

Mitchell J. Stansloskib, Walajabad S. Sampathb, Edwin K.P. Chongd

a The Boeing Company, M/S 4A-08 P.O.Box 3707 Seattle, WA, USA

bDepartment of Mechanical Engineering, Colorado State University, Fort Collions, CO, USA

cDepartment of Civil and Environmental Engineering, Colorado State University, Fort

Collions, CO, USA

dDepartment of Electrical and Computer Engineering, Colorado State University, Fort

Collions, CO, USA

Abstract

The purpose of this paper is to present a real world application of an innovative hybrid

system reliability optimization algorithm called TAGA. This TAGA algorithm

combines Tabu Search and Genetic Algorithm to provide a more efficient search

method. This new algorithm is applied to an aircraft structure to optimize its reliability.

For retrofitting the horizontal stabilizer under severe stall buffet conditions, a Decision

Support System (DSS) is developed using the TAGA algorithm. This system solves a

reliability optimization problem under cost and weights constraints. The DSS contains

three components: a Graphical User Interface (GUI), a database and several modules to

provide the optimized retrofitting solutions. The GUI receives input from the user with

number of stall buffet flights and their mission types. The DSS provides several non-

dominant solutions and their rankings. The solutions include where to install doublers

and stiffeners. Compromise Programming is used to rank all non dominant solutions.


71

When the full combination of all input variables increases exponentially, the proposed

DSS become very efficient. In order for this DSS to work effectively, the underlying

database of fatigue damage rates are pre-determined by a reliability model. This DSS

helps decision maker to choose the best plan to execute prior to the airplane’s fatigue

test, so that the aircraft can sustain the fatigue test without having to stop for repairs.

This paper presents an application of the TAGA meta-heuristic algorithm for solving

nonlinear multi objective reliability optimization problems embedded in a DSS.

Key words:

Multi objective reliability optimization; Tabu Search; Genetic Algorithms; Comprise

Programming; Epsilon Constraint Method; Redundancy Allocation; Decision Support

Systems; Fatigue Life; Stall Buffet.


72

#182

Induction of Through-Thickness Compressive Residual Stress Fields in

thin Al2024-T351 Plates by Laser Shock Processing

J.L. Ocaña, C. Correa, J.A. Porro, M. Díaz, L. Ruiz de Lara, D. Peral

UPM Laser Centre. Ctra. Valencia, km. 7.3. 28031 Madrid (SPAIN). E-

mail: [email protected]

Abstract

The capability of Laser Shock Processing for the induction of RS’s fields in sub-surface layers

of relatively thick specimens (d > 6 mm) in view of the improvement of their fatigue life has been

widely demonstrated. However, the LSP treatment of relatively thin specimens (normally d < 6

mm, but also thicker ones depending on the treatment intensity) brings, as an additional

consequence, the possible bending of the treated specimen, a feature that can otherwise be

employed for forming procedures according to the laser shock forming process.

This effect poses a new class of problems regarding the attainment of specified RS’s depth

profiles in the mentioned type of sheets, as their self-equilibration reaction after clamping removal

can considerably alter the primary laser shock induced RS’s fields, thus possibly motivating

undesired final RS’s field distributions, and, what can be more critical, an overall deformation of

the treated component.

With the aid of the calculational system available at CLUPM (see figure), the analysis of the

problem of LSP treatment for induction of tentatively through-thickness RS’s fields for fatigue

life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece

deformation due to spring-back self-equilibration has been envisaged. Numerical results directly

tested against experimental have been obtained and optimized in order to induce specified kinds

of RS´s profiles while maintaining acceptable global sheet deformations.

Figure 1 – Computational results of X (left) and Y (right) components of surface residual

stresses obtained in sample specimen by LSP

On this basis, the use of the code has been applied to the specification of LSP treatments for

obtention of RS's fields tentatively able to retard crack propagation on normalized specimens. A



73

convergence between numerical code results and experimental results coming from direct RS's

measurement is presented as a first step for the treatment of the normalized specimens under

optimized conditions and verification of the crack retardation properties virtually induced.

Acknolwledgements: Work performed under national Spanish funding (MAT2012-37782)


74

Session 3B

MON, 16:00-17:15

Room Berlin

TOPIC: Processes

Chair: Mario Vaz


75

#101

Structural Assessment of Fine-scale Structures Produced by Complex

Metal Forming Processing

Janusz Majta

1, Marcin Kwiecien

2, Krzysztof Muszka

3, Paulina Graca

4

1AGH University of Science and Technology, Faculty of Metals Engineering and Industrial

Computer Science, Mickiewicza 30, 30-059 Krakow, Poland, [email protected]

2,3,4AGH University of Science and Technology, Faculty of Metals Engineering and Industrial

Computer Science, Mickiewicza 30, 30-059 Krakow, Poland

Abstract The study aims at development of novel, re-engineered metallic materials by

introducing gradual changes into their microstructures (through a combination of fine

precipitates and nano-layers/areas within a typical grain structure), with the main objective to

enhance the mechanical properties of these materials through special variations of deformation

mode and material microstructure. The highly refined structure was obtained by complex metal

forming procedures as an effect of wire diameter reduction, bending, tension, torsion, wire

flattening as well as accumulative roll bonding. These processes allow to obtain a severely

deformed and high inhomogeneous microstructure of multilayered metal-metal composite. In

this paper, deformation behavior and size effects are illustrated by means of UFG (ultrafine-

grained) microalloyed steel with different combinations of microstructure length scale and

deformation inhomogeneity. It has been shown that control of the microstructure development

leads to nanoscale multilayered structures characterized by attractive combination of strength,

ductility and fatigue. For the use of UFG microalloyed steels subjected to the SPD (severe plastic

deformation) processing as attractive structural materials, restoration of ductility should be

addressed. Presence of fine precipitates of microalloying elements and refined pearlite colonies

can be used to improve the desired combination of strength and ductility. The texture analysis

was also consequently performed, both experimentally and numerically. The non-linear

combined hardening model was applied to capture the strain path effects with special emphasis

on the role of the inhomogeneity of the accumulated energy. Finally, it is shown that both the

complex strain path history and the multilayered structure evolution can be quantitatively

characterized numerically.

Acknowledgment

The financial support of Polish National Science Centre, research grant:

DEC-2012/05/B/ST8/00215, is highly appreciated.



76

#105

Damage tolerance improvement of laser beam welded fuselage

structures via crenellations

J. Lu*, N. Kashaev and N. Huber

Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht,

Max-Planck-Str. 1, 21502 Geesthacht, Germany.Contact: [email protected]

Abstract

Damage tolerance is the major principle adopted to safeguard the structural integrity of an

aircraft in the presence of damages from different sources throughout their service life. This

principle requires significant considerations already in the design stage of the aircraft. In this

paper the concept of geometrical modification of the skin by so-called crenellations [1,2] in a

laser beam welded integral structure (Fig. 1a) is addressed. This aims at improving the damage

tolerance performance of the structure by systematic variation of the thickness maintaining

constant weight. The effectiveness of this concept was experimentally verified by comparing

fatigue life of cruciform panels (with and without crenellations) under service-related biaxial

loading conditions (Fig 1b). Using an FEM model a reasonable prediction of the fatigue crack

growth was achieved. As the thickness variation has been already intensively studied in [1,2] our

particular interest is the sensitivity of the fatigue life with regard to orientation effects and their

fundamental understanding. The goal of this work is an optimization of the crenellation geometry

in combination with stiffeners, as sketched in Fig. 1a.

Figure 1 (a) test coupon of fuselage panels with welded stringers (b) experimental setup of

fatigue tests under biaxial loading conditions

References

[1] Uz, M.-V. et al., Int. J. Fatigue 31, 916-926, 2009

[2] Uz, M.-V. et al., Proceedings, ICAF 2011, pp. 811-826, 2011.

(a) (b)


77

#138

Mechanical Behavior of Friction Stir Welded Butt Joints

Ana C.F. Silva1, Daniel F.O. Braga

2, Frederico Silva Gomes

2, Miguel A.V. de Figueiredo

3,

P.M.G.P. Moreira2

1 Institute of Mechanical Engineering and Industrial Management (INEGI), University of Porto,

Portugal [email protected]

2Institute of Mechanical Engineering and Industrial Management (INEGI), University of Porto,

Portugal

3Department of Mechanical Engineering (DEMec), University of Porto, Portugal

Abstract Friction stir welding (FSW) is a highly reliable joining process capable of creating

excellent opportunities for new structural design concepts for several industries, like aeronautic,

aerospace and railway. The process was initially developed for aluminium alloys, but since then

FSW was found to be suitable for joining a large number of materials, such as aluminium,

magnesium, steels, titanium and others. It produces nearly defect-free welds for such demanding

applications as aerospace structures at lower cost than conventional fusion welds. A schematic

image of the process is presented in the Figure 1.

Figure 1 - caption for the Figure Friction stir welding process schematic representation, adapted from

Standard ISO 25239-1.

The process understanding and the possibility of predict joint mechanical behaviour is important

for new structural developments, especially in industrial environment. In this work digital image

correlation (DIC) was applied in order to achieve the full displacement and strain field of a friction

stir welded specimen. In order to avoid defect effects, a previous optimization of the process was

performed using the Taguchi methodology. This method is a quality control method that offers a

simple mean of analysis and optimization of complex systems. The deformation field of the weld

zone was determined and the different welded zones of friction stir welded butt joints were also

achieved.



78


79

#141

Manufacturing and characterization of nanostructured Al-Si-Si3N4-C

composites for high-wear application

Malgorzata Sopicka-Lizer1, Jerzy Myalski

1, Daniel Michalik

1, Tomasz Pawlik

1, Nathalie

Valle2, Agnieszka Boto-Probierz

2

1 Silesian University of Technology, 44-100 Gliwice, Akademicka 2A, Poland; e-mail:

[email protected]

2 Centre de Recherche Public – Gabriel Lippmann, Luxembourg

Abstract Nanostructured aluminium and AK-12 based composites with 15 wt% of Si3N4

reinforcement and 5wt% of glassy carbon addition were prepared as a result of the cold isostatic

pressing followed by free-sintering or hot-pressing of the composite powder obtained via

mechanochemical processing of the initial components. Differential scanning calorimetric (DSC)

and XRD studies were applied for characterization of the composite powder behaviour while

scanning and transmission microscopes were used for characterization of the specimens

microstructure after a thermal treatment. Mechanical (flexural strength, hardness and elastic

modulus) and tribological properties were examined as well as. It has been found that

mechanochemical treatment led to the replacement reaction in the Al-Si-N-C-(O) system and

some amount of amorphous phase was present apart from the composite particles formation and

a limited increase of oxygen content. It is assumed that carbon presence and silicon existence in

AK-12 alloy improved the milling performance and it limited the range of the replacement

reaction.

The cold isostatic pressing under 350 MPa led to compaction of the composite specimens and

aluminium plastic deformation. The last step of manufacturing involved free sintering in argon

atmosphere over the temperature of metal alloy melting, however, the resultant specimens showed

noteworthy porosity in the range of 20 vol.%. Thermal treatment led to crystallization of the

amorphous phase and AlN was detected after XRD examination. The microstructure studies

showed formation of the transition zone of the complex chemical composition between all the

types of the reinforcing particles and the matrix. All specimens showed excellent tribological

properties against a cast iron pin in the reciprocating tribological test. It has been found that carbon

presence significantly improves mechanical and tribological properties of the resultant

composites. Application of hot pressing without the step of a cold isostatic pressing did not

improve mechanical properties of the final material, as well as its wear properties were not better.

Formation of Al4C3 as a result of the reaction between the graphite die and the specimen after the

hot-pressing treatment was also observed.


80

#143

Development of multi-layer fibrous composites for fire resistant and

sound insulating doors

Fernando Cunha1, Carlos Mota

1, Raul Fangueiro

1, Manuel Ferreira

1, Nelson Silva2

1, University of Minho, School of Engineering, Portugal,

2 CIPS company, Fontão- Ponte de Lima

[email protected]

Abstract

This paper reports the development of new type of composite materials based on multilayer

concept. The multilayer composites were mainly composed of waste fibre based nonwoven

fabrics, woven glass fibres and wood layers. Each of these layers was designed to operate with

different functionalities; but when these layers were combined into a single composite, these

functionalities were expected to work together. This particular aspect allowed to develop a single

structure for fire doors (fire resistance time of more than 90 min), as well as to get a better acoustic

insulation behaviour (up to 47 dB). The multilayer structure was comprised of different layers

such as MDF panels (2 mm), woven glass fibre layer (220 and 400 g/m2), wood materials (10

mm), woven glass fibre (220 and 400 g/m2) and waste fibre based no-woven fabrics (3 different

types). Composite panels were produced using these combinations in a compression moulding

machine using two types of thermosetting resin systems. Acoustic insulation behaviour of these

composites was characterized using a method similar to the one applied in the EN ISO 140-3

standard. In this testing method, a white noise was applied in an insulated chamber and the noise

level (in decibels, dB) for various frequencies was measured in the first and second compartments

of the chamber. The difference between the noises measured in those two compartments, called

the noise reduction coefficient (α), was used to assess the acoustic insulation behaviour. It was

observed that a good noise reduction coefficient (up to 47 dB) was observed in case of developed

composite materials at 500 Hz frequency. It was also observed that increasing the thickness of the

panels was not found beneficial for sound reduction capacity and the use of non-woven fabrics in

the panel increased the noise reduction coefficient significantly.

Acknowledgement

The authors are grateful for the financial support received from the Research Grants QREN,

project SI&IDT nº 24897.



81

Session 4A

TUE, 11:30-13:00

Main A

TOPIC: Processes

Chair: Peter Horst


82

#171

Cold plasma treatment of polymeric matrix composites

F. Velasco, A. Bautista, S. Guzmán, M. Pantoja

Department of Materials Science and Engineering and Chemical Engineering. Universidad

Carlos III de Madrid. Av.Universidad, 30. 28911 Leganés, Spain

Abstract Atmospheric pressure plasma is a fast, clean, environmentally friendly surface

treatment. It does not generate any wastes, and it is highly effective to improve adhesion

properties through surface energy increase. Atmospheric plasma is able to promote the adhesion

of surfaces, mainly due to two effects: cleaning and activation. This work studies the effect of

plasma treatment on a glass fibre reinforced epoxy used in construction applications, as well as

in the plain epoxy matrix.

For a given torch-to-sample distance, two plasma torch speeds were selected: 1 and 10 m/min.

Contact angle measurements were carried out with water, glycerol and diiodomethane, both

immediately after surface treatment. Data were analyzed using Owens-Wendt-Rabel-Kaelble

(OWRK) method to calculate surface energies. Contact angle for all tested liquids decreases with

plasma surface treatment, in particular for the lowest speed. Hence, surface energy (wettability)

improves in all materials with plasma treatment, specially for lower rates (longer treatment times),

as shown in Figure 1. This fact is due to the higher exposition time, subsequently the surface is

more activated. A big effect on the polar part of the energy was found, appearing species with

free electrons on the surface that can improve the adhesion. Surface energy (wettability) is

reduced after 30 days from surface treatment, being the polar part of the energy (polarity of the

surface) strongly reduced with time.

Composites were painted. After plasma treatment, visual inspection shows better adhesion,

and a pull-off test was used to evaluate it. Adhesion tensile stress increases, and the standard

deviation of the measurements decreases (reliability is improved). Finally, scratch tests were

carried out, showing better performance the coatings painted after plasma treatment.


83

Figure 1 – surface energy of studied GFRP untreated and after APPT treatment

0

5

10

15

20

25

30

35

40

45

50

Untreated 10 m/min 1 m/min

Su

rface e

nerg

y (

mN

/m)

Total surface energy

Dispersive part

Polar part


84

#173

Modification of metallic surfaces by duplex treatments involving

severe shot peening, pulsed electron beams and nitriding.

T. Grosdidier1,2

, Y. Samih1,3

, B. Beaussir1,2

, T. Czerwiec 1,4

, S.Z. Hao 3, C. Dong

2,4,

1Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux, CNRS UMR

7239 - Université de Lorraine, 57000 Metz, France 2LABoratoie d'EXcellence Design des Alliages Métalliques pour Allègement de

Structures, Île du Saulcy, 57000 Metz, France 3Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian

University of Technology, Dalian, 116024, P.R. China 4 Institut Jean Lamour, Département CP2S, CNRS UMR 7198, Université de Lorraine,

Parc de Saurupt, 54000 Nancy, France

Abstract Long term surface peening, such as the Surface Mechanical Attrition Treatment

(SMAT), was developed to upgrade directly the mechanical properties of the materials as

well as a surface activator prior to chemical treatments such as Plasma Nitriding [1]. The

High Current Pulsed Electron Beam (HCPEB) technique is also a recent technique that

has been proved to increase surface hardness as well as improve wear and corrosion

properties [2]. These techniques create a deformed graded surface for which the grain size

reduction, the increased grain boundary density and the introduction of structural defects

(twins, dislocations, vacancies …) improve directly the properties. It was also suggested

that they promote the diffusion of nitrogen and thereby, the reductions in the nitriding

temperature and/or duration, leading to avoid the formation of nitrides which affect the

corrosion behavior of stainless steels.

In the present work, the AISI 316L stainless steel was treated by SMAT or HCPEB under

different processing conditions then subjected to Plasma Nitriding under 'soft' conditions

(350 °C for 8 hours). The evolutions of the nitrided depths and hardness of the processed

surfaces are analyzed and their evolutions discussed depending on the processing

conditions at the light of quantitative analysis of the deformed state using a recently

developed procedure [3].

This new procedure -based on the analysis of Geometrically Necessary Dislocation

(GND) and grain size determination obtained from EBSD orientation maps- which has

been used to study quantitatively the surface and sub-surface microstructural changes

issued from SMAT is here extended to the analysis of duplex treatments involving plastic

deformation and nitriding.

[1] Lu K, Lu J. Nanostructured surface layer on metallic materials induced by surface

mechanical attrition treatment. Mater Sci Eng A, 375–377, 2004, 38–45.

[2] Grosdidier T, Zou JX, Stein N, Boulanger C, Hao SZ, Dong C. Texture

modification, grain refinement and improved hardness/corrosion balance of a FeAl alloy


85

by pulsed electron beam surface treatment in the “heating mode.” Scr Mater, 58, 2008,

1058–1061.

[3] Samih Y, Beausir B, Bolle B, Grosdidier T. In-depth quantitative analysis of the

microstructures produced by Surface Mechanical Attrition Treatment (SMAT). Mater

Charact, 83, 2013, 129–138.


86

#174

A study on the effect of weld induced residual stresses and the

influence of weld sequencing of centrifugal extractor rotating bowl

using numerical simulation and experimental validation

Satish Kumar Velaga*, Gaurav Rajput, T. Selvaraj, B.M. Anandarao, A. Ravisankar

Reprocessing Plant Design Division, Reprocessing Group,

Indira Gandhi Centre for Atomic Research

Kalpakkam 603102.

*Corresponding author E-mail: [email protected]

Abstract: Centrifugal Extractors (CE) are the most preferred extraction equipment for the

separation of fissile material from radioactive fission products in fast reactor fuel reprocessing in

order to reduce damage to the solvent by minimizing the residence time. During fabrication of

thin section high speed CE rotating bowls, several aspects such as heat input, weld speed, groove

geometry, number of passes and weld sequencing are very important factors to be considered to

control weld induced residual stresses and distortions. The thermal cycles due to concentrated heat

input applied during the welding process, generates inhomogeneous plastic deformation and in

turn the residual stresses in the weld metal. The presence of tensile residual stresses increases

the

susceptibility of a weld to fatigue damage, stress corrosion cracking (SCC) and fracture.

To analyze the above effects, a 3-D finite element analysis for a three plane GTAW

circumferential butt joint is carried out to predict weld induced residual stresses and distortions

during fabrication of CE rotating bowls. The GTAW process was simulated using a nonlinear

heat transfer analysis using the Sysweld software with the moving double ellipsoidal heat source

model and a sequentially coupled thermo-metallo-mechanical analysis. This study includes

temperature dependent thermo-physical, thermo-mechanical properties and isotropic hardening

model. The axial and hoop residual stresses on the inner and outer surfaces were computed. Tensile

residual stress on the inner surface and compressive residual stress on the outer surface were

observed and their impacts on the CE rotating bowl are discussed. The importance of weld

sequencing and its inference on welding distortion is investigated and validated against the

experimental measurements.


87

Figure 1 – (a) 3-D model (b) FE mesh Figure 2 – Five different cases of weld sequencing


88

#128

Internal Expansive Reactions in Concrete Structures – Deterioration

of the mechanical properties

João Custódio1, António Bettencourt Ribeiro

2

1LNEC – National Laboratory for Civil Engineering, Materials Department, Av. do Brasil, 101,

1700-066 Lisbon, Portugal, [email protected]

2LNEC – National Laboratory for Civil Engineering, Materials Department, Av. do Brasil, 101,

1700-066 Lisbon, Portugal.

Abstract In the last decade, a significant number of problems related to concrete deterioration

have been detected in large concrete structures in Portugal and throughout the world; the leading

cause being internal expansive reactions (IER), more specifically, alkali-silica reaction (ASR) and

internal sulphatic reaction (ISR). The reasoning behind the detection of an increasing number of

affected structures is threefold, greater awareness of the technical and scientific community

regarding IER, improvement of the methods utilized in IER diagnosis, and the fact that IER

distress signs only appear several years or decades after construction. Current knowledge on IER

does not allow for a complete assessment of the actual condition of an IER affected structure and

the accurate prediction of the deterioration of the mechanical properties and, consequently, of the

period during which the structure will effectively perform its function, essential for the timely and

cost-effective planning of the necessary mitigation/rehabilitation/reconstruction works. This is of

upmost importance in large concrete structures, like bridges and dams, where IER can have severe

consequences in terms of structural safety and serviceability. Therefore, to help surpassing this

situation, a research project is being conducted at LNEC to contribute to the establishment of a

method for the accurate determination of current level of IER progression and for obtaining data

relating the level of expansion with deterioration of mechanical properties. These are essential to

the adequate overall appraisal of an affected structure, and the development of structural models

that predict risks to structural integrity, potential for further deterioration due to other

mechanisms, need for mitigation/remediation actions, and the remaining service life of the

affected structure, as acknowledged in the “IStructE ASR Technical Guide” and “IStructE

Appraisal of existing structures”. This communication presents the results, from the

aforementioned study, concerning the assessment of the effect that internal expansion has in the

deterioration of the concrete mechanical properties, more specifically in its stiffness, currently

considered has being the concrete mechanical property most sensitive to deleterious expansion.


89

Figure 1 – Example of a concrete structure affected by ASR.


90

#189

A comparison between the deformation behaviour of dissimilar

AA2024‐T3/AA7050‐T7651 welds produced by Stationary Shoulder

Friction Stir Welding and standard Friction Stir Welding

A. Barbini, J. Carstensen, J.F. dos Santos

Helmholtz‐Zentrum Geesthacht GmbH, Institute of Materials Research, Materials

Mechanics, Solid‐State Joining Processes (WMP), Geesthacht, Germany

Abstract The present work involves the study of the mechanical behaviour of welds obtained

with Stationary Shoulder Friction Stir Welding (SSFSW) and standard Friction Stir Welding

(FSW) for dissimilar joints between aluminium alloys AA 2024‐T3 and AA7050‐T7651. The

main objective is to compare the two technologies for a possible application in primary

components of aircrafts.

Three different welding speeds (WS) were used to establish the effects of variations in Heat

Input (HI) on the weld performance. Preliminary studies showed that positioning the AA 2024‐

T3 in the Advancing Side of the weld leads to superior performances.

Due to the asymmetry of the joints, caused by the process itself and by the dissimilar welding

configuration, the tensile test (ASTM E8‐09) was combined with a Digital Image Correlation

method that allows the understanding of the different deformation behaviour of the two materials

under loading.

Common characteristics were noticed for both processes. The AA 7050‐T7651 does not

reach the yield stress in any of the cases analysed. A high peak of the major strain in the Stir Zone

can be observed beside the border with the AA 2024‐T3. The peak starts at the same moment in

which the AA 2024‐T3 enters in the plastic field and increases during the application of the load

until the failure. In the AA 2024‐T3 is noticed the formation of a secondary peak of the major

strain in the Heat Affected Zone.

SSFSW is characterised, considering different sections along the specimens, by more

homogeneous deformation behaviour along the welding width than in FSW. At a certain load

level the peak of major strain is higher in FSW than in SSFSW, agreeing with the better values

recorded in the tensile test of the SSFSW specimens. For both processes, a decrease in the HI (i.e.

increasing the WS) results in improved properties.


91

Session 4B

TUE, 11:30-13:00

Main B

TOPIC: Testing

Chair: Malgorzata Kujawinska


92

#184

Considerations on the choice of the drilled hole diameter in ESPI-

HDM residual stress measurements in Ti6Al4V

C. Barile1, C. Casavola

1, G. Pappalettera

1, C. Pappalettere

1

1Politecnico di Bari, Dipartimento di Meccanica, Matematica e Management, viale Japigia 182,

70126 Bari, Italy [email protected]

Abstract The hole drilling method (HDM) is the most general approach used to measure

residual stress profiles in components. It consists in executing a very small hole and then in

measuring the relieved strain by using a strain gage rosette placed in an area close to the hole

itself. Nowadays HDM together with X-ray diffraction are the only practices subjected to

standardization, even if, in the last years, it has been modified by replacing strain gage transducers

with full field optical techniques like Electronic Speckle Pattern Interferometry (ESPI). This

ensures higher sensitivity measurements and avoid the long and expensive step of transducers

application. Several set-up parameters are involved in this kind of approach: drilling feed rate,

hole depth, cutter milling diameter and so on. In this paper the effects of the choice of cutter

milling diameter are discussed. It is known, in fact, that the strain field magnitude measured at a

certain distance from the hole depends on the squared value of cutter diameter. A Ti6Al4V

specimen was loaded in a four-point bending frame in order to introduce a well-known state of

stress in the sample with zero stress along the transverse direction and σ=133.5 MPa along the

longitudinal one. ESPI - Hole drilling measurements were then performed by using two different

drilling bits whose diameter was 1/16’’ and 1/32’’ respectively. Hole diameter deeply affects the

entity of measured relieved strain. Furthermore it represents the starting point to proper define the

analysis area that is to say the portion of the image that will be used for the strain measurement.

This area is given by a circular crown concentric to the drilled hole being defined by two radius,

internal and external radius, starting from the center of the hole. Reducing too much internal

radius can lead to include plasticity effects of hole drilling, while if it is kept too big one can

exclude significant strain field data. The proper choice depends on the material behavior and on

the hole diameter. Usually internal radii are double of the hole diameters and external radii have

the maximum value compatible with the camera field of view. In this paper considerations about

the proper definition of the area of analysis are reported in connection with the radius of the drill

bit adopt. It was found that better results for the small diameter drill bit are obtained by increasing

the internal radius. This attitude could be due to the more accentuate hole curvature which

contributes together with thermal effect to the creation of a plasticization area around the hole.

This trend was confirmed by analyzing the stress curve by varying the internal radius: deeper was

the hole, more was the convergence between the optimal internal radius values for the two mills

since the temperature effects on the surface are less accentuated. As a final result it was found

that, for the level of applied load, the cutter mill diameter didn’t affect substantially the

measurement accuracy on titanium specimen and this represent an important result and it should

be compared with the analogous results reported in literature for steel. In that case, in fact,

substantial influence of the drill bit diameter was found. Explanation for this discrepancy can be

found by comparing the Young moduli of the two materials. In the case of steel the higher value



93

of the Young modulus joined with the choice of a small diameter drill bit leads to a low strain

field around the hole harder to be detected and measured and, as a consequence, most subjected

to measurements errors.


94

#188

Experiment Research and Application on Super-Retarding Mortar

Xin Feng1, Xianyan Zhou

2

1College of Civil Engineering and Mechanics,Central South University of Forestry and

Technology, South Shaoshan Raod NO.498, Changsha Hunan 410004, PR China. E-mail:

[email protected]

2College of Civil Engineering and Mechanics,Central South University of Forestry and

Technology, Hunan, PR China.

Abstract In scores of experiments indicates that the super-retarding mortar, keeping plasticity

long-term, can make cement setting and hardening at a slower speed through chemical additive.

Based on large numbers of orthogonal tests and theoretical analyses, the super-retarding mortar

which satisfies the demands of actual engineering was developed successfully in present paper.

And it is consist of cement, sand, water and composite retarder blended in an appropriate rate.

From 0℃ to 40℃, setting time can be adjusted from 1 day to 22 days in the light of to the

engineering requirements, and after condensation, it begins to harden gradually and ends with the

compression strengthen over 30MPa. In this study, experiments were employed to test the

influences of accession amounts of composite retarder dosage on setting time and compression

strengthen of super-retarding mortar. On the other hand, the retarding mechanism of super-

retarding mortar was studied, and the super-retarding mortar was applied to experimental models.

The results show that super-retarding mortar used in this study can be applied to the actual

engineering, and it can be treated as the theoretical reference for the actual project application of

the new retard-bonded prestressed concrete system.



95

#135

Characterization of orthotropic stiffness components of Pinus pinaster

from heterogeneous plate bending tests

W. Cruz 1, J. Xavier

1,2, F. Pierron

3, J. Morais

1

1Centre for the Research and Technology of Agro-Environmental and Biological Sciences,

CITAB, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801 Vila

Real, Portugal, {jmcx,jmorais}@utad.pt

2INEGI/LOME, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal,

[email protected]

3Faculty of Engineering and the Environment, University of Southampton, Southampton SO17

1BJ, UK, [email protected]

Abstract This work presents a study on the characterization of longitudinal-radial orthotropic

elastic properties of Pinus pinaster Ait. wood through a heterogeneous plate bending test. The

proposed approach couples the deflectometry optical technique with the virtual fields method

(Fig. 1). Using this inverse identification method, all components of the bending stiffness matrix,

governing the Love-Kirchooff classical plate theory, can be determined from a single test. The

approach was firstly validated using a finite element model of the bending test considering five

different loading cases. Experimentally, a procedure was implemented in order to coating the

surface of the solid wood plate in order to guarantee the specular reflection required in the

deflectometry technique. The curvature fields required in the identification problem were

numerically reconstructed from the slope fields by means of a polynomial approximation. The

curvature fields, together with the applied punctual load and the plate dimensions were then input

in the virtual fields method for material parameter identification. The values of the engineering

constants obtained from the proposed approach were found in good agreement with regard to

reference ones reported in the literature for the same species and determined from independent

classic tensile and shear mechanical tests (Table 1).


96

Figure 1 - Schema of the plate bending test.

Table 1 - Engineering constants determined by the VFM.

EL

(GPa)

ER

(GPa) LR

GLR

(GPa)

Reference 15.13 1.91 0.47 1.12

Mean 12.55 1.396 0.639 1.190

Std 5.319 0.237 0.371 0.145


97

#172

Sloshing effect on the dynamic behavior of large capacity horizontal

cylindrical tank due to seismic excitation and it's qualification

Sanatana Maharana1, Sunil Kumar Gupta, T. Selvaraj, B.M. Ananda Rao, A.

Ravisankar

1Reprocessing Projects and Operations Group, Indira Gandhi Centre for Atomic Research,

Kalpakkam, India, Pin-603102, Tel.: +91 44 27480500 Ext: 26959; Fax: +91 44 27480207

[email protected]

Abstract

Ground supported and elevated tanks of various sizes and configurations are widely used in

nuclear industries for handling nuclear process liquids. Horizontal cylindrical tanks are

employed in nuclear reprocessing plant for storing high level wastes (HLW). Since the HLW

generate decay heat, cooling coils provision are made for circulation of process cooling water

for heat removal. Seismic safety of these liquid storage tanks is of considerable importance to

ensure leak proof and must remain functional in post earthquake period. During lateral base

excitation the free surface liquid oscillates with different modes and the seismic ground

acceleration causes hydrodynamic pressure on the tank wall which in turn causes the failure of

tanks due to buckling. Hence earthquake-induced sloshing effect has been recognized as an

important issue toward safeguarding the structural integrity of liquid storage tanks and vessels.

Evaluation of sloshing effect requires knowledge of sloshing frequency of liquid, hydrodynamic

pressure on the tank wall and seismic force due to sloshing. Hydrodynamic pressure depend on

the geometry of tank, height of liquid, properties of liquid and fluid-tank interaction. The

pioneering work of Housner and the design codes based on "impulsive-convective"

decomposition of the container-fluid motion is limited to non-deformable vertical circular and

rectangular tanks. The present paper investigates sloshing effects on the earthquake design of

188 m3 capacity horizontal cylindrical HLW storage tanks. Since the HLW tank comprises of

baffle plates, ballast tanks, internal cooling coils and due to the limitation of studies available on

the spring-mass model of horizontal cylindrical tanks with internal obstruction, a detailed study

is done to obtain the sloshing frequency, hydrodynamic pressure and detailed finite element

analysis carried out for qualifying the HLW tank subjected seismic excitation and results are

discussed.


98

Figure 1 - Stress plot for load combination consists dead weight, hydrodynamic pressure

and seismic forces in x-excitation.


99

#180

Fatigue cracks thermal patterns

António Silva1, P.M.G.P. Moreira

2, Mário A.P. Vaz

2, Joaquim Gabriel

1

1MLABIOMEP, IDMEC – Polo FEUP, Rua Dr. Roberto Frias, Porto Portugal

2INEGI, Rua Dr. Roberto Frias, 400, Porto Portugal

Abstract Nowadays the main cause of failure in mechanical components is due to fatigue

cracks therefore, the correct prediction, location and monitorization of danger regions is

extremely important. This is extremely important in aeronautics since it can lead to disasters and

catastrophic situations. Generally, al the materials increase or decreas their local temperature

wend subjected to some sort of stress. In most cases a positive stress (traction) will lead to a

decrement in the temperature and vice versa. In the case of aluminum a stress amplitude of

0.4MPa with a frequency between 5 and 200 Hz would induce a temperature increment of 1mK.

In this work were used two different frequencies, 10 and 100 Hz. The test specimen was a CT

according with the ASTM E647 standard. The sample was subjected to 50K cycles to initiate the

fatigue crack. The sample was monitored with a FLIR SC7500 thermal camera with force

reference. The acquired data was processed in two different manners: A) with the IrNdt software

and B) with a costume made application developed in LabVIEWTM. The costume made

application compensate the vertical and periodic movement of the sample and therefore reduce

the noise. The results at this point are not yet conclusive but provide a good indication of the

possibility of measuring the stress using only thermal information.

Figure 1 – Phase image resulting from thermal analyses.

Crack tip


100

Session 5A

TUE, 14:15-15:30

Room Lisboa

TOPIC: Models

Chair: Carmine Pappalettere


101

#142

Predicting the fatigue life of mechanical components using continuum

damage mechanics (cdm): application to a railway axle

Zoser Kalengayi T.1, Juan Carlos P.

1, Cristina Castejón S.

1, María Jesús G.

1

1 Departamento de Ingeniería Mecánica, Grupo de Investigación MAQLAB,

Universidad Carlos Tercero de Madrid

Abstract: During the last years, safety in the railway sector has been considerably improved.

Mechanical components are increasingly reliable and with better performance. However

components like railways axles, although they are designed for an infinite life, display cracks

within just a few hours after starting operating, causing additional maintenance costs and machine

standstill. The safety and reducing costs requirements tackle the fatigue phenomena in railway

axle from another perspective. This paper presents an application of the Continuum Damage

Mechanics (CDM) to the case of railway axle under constant and variable loads. This theory

allows the non-linear damage accumulation and the sequence effect to be taken into account,

improving the fatigue life prediction. A Damage variable is defined and used to characterize the

railway axle’s state at a specified number of load cycles. The number of cycles for a mesoscopic

crack initiation, the size of crack initiated and the fatigue life are calculated under different load

conditions.

Keywords: Fatigue, Damage Mechanics, CDM, Railway axle.

[1] Lemaitre J., Chaboche J.L., Ahmed B., Rodrigue Desmorat, Mécanique des Matériaux

Solides, Paris, 2009.

[2] David L. McDowell, Applications of continuum damage mechanics, Barr Harbor Drive,

1997. [3] J. Skrypek, A. Ganczarski, Modeling of Material Damage and failure of structures. Theory

and Applications, Springer, Berlin. 1999

[4] Lemaitre J., A course on Damage Mechanics, Springer, Berlin, 1996. [5] Lemaitre J., R. Desmorat, Engineering Damage Mechanics: Ductile, Creep, Fatigue and

Brittle Failure, Springer Verlag, Berlin, 2005


102

#145

Dynamic models in stress wave dispersion filtering in the Hopkinson

Pressure Bar

Francisco Q. de Melo(1)

Mário A.P. Vaz(2)

Jaime M. Monteiro(2)

(1) Department of Mechanical Engineering, University of Aveiro

(2) – LOME, Laboratory of Experimental Dynamics and Advanced Materials; Department of Mechanical

Engineering; Faculty of Engineering, University of Porto

Summary

The wave dispersion observed in the stress wave records with the Hopkinson bar in testing

materials under high strain rates is an unfavorable phenomenon when accurate

constitutive relations for materials subjected to high strain rates are requested. In this

paper, the raw stress wave signal is treated as an equivalent external dynamic force that

loads an equivalent dynamic system, consisting in a spring, a viscous damper and an

inertial mass. The system transmissibility to a reference foundation is equivalent to the

filtered stress-strain signal of the material in test, where the tuned damping characteristics

of the system lead to an efficient adjustment of the stress-strain signal now clean of

dispersive frequencies

Keywords: Dispersion waves, Hopkinson pressure bar, filtering techniques


103

#146

Sensitivity of Material Parameters on the Fatigue Crack Growth

Calculations

S.M.O. Tavares1, P.M.S.T. de Castro

2

1Institute of Mechanical Engineering and Industrial Management (INEGI), Porto, Portugal

2Faculty of Engineering of the University of Porto, Portugal

Abstract The aeronautical sector has been exploring in depth the different properties of the

materials enabling continuous improvement of the aircraft efficiency and effectiveness, in line

with the demand of the “Quieter, Cleaner and Greener” or “More Affordable, Cleaner and

Quieter” air transportation aims. This trend has been putting pressure on manufacturers to invest

in R&D in order to create new solutions that meet these new needs. From the structural point of

view, these new solutions can be developed based on new materials or new structural concepts

with the major objective of aircraft weight reductions, which will lead to lower fuel consumption,

lower operational costs and lower greenhouse gases. The continuous development of new

materials and new manufacturing processes requires a permanent characterization of their

mechanical properties for a correct evaluation of their benefits and drawbacks when compared

with the present solutions. Concerning metallic airframes, they are commonly designed based on

the damage tolerant philosophy, which allows to reduce the structural weight and, at the same

time, increase the reliability and the integrity in the presence of inherent damages which may have

occurred during the manufacturing process or induced during the service or due to the structure

aging. However, the application of this design concept requires an extensive know-how of the

fatigue and fracture properties of the employed materials. This knowledge is essential to define

the maximum damage or flaw size that allows the structure to operate safely until the next

maintenance check-up and the number of cycles and the intervals of structural inspections.

This article analyses the material data related with fatigue crack growth rates used to estimate

the fatigue life of structures when a flaw is identified. These material data have an inherent scatter

mainly due to two different aspects: (i) material variability and (ii) properties measurement

characteristics. The material discrepancies can be caused by differences on its chemical

composition, its manufacturing process, applied heat treatments or even on the conditioning mode

and time. The measurement of the crack growth rate properties may also be subjected to

differences due to the testing environment (temperature, humidity, etc.), testing equipment (crack

measurement, load application, testing frequency) and technician capabilities. These different

characteristics create discrepancies on the crack growth properties. In order to reflect this crack

growth scatter, a sensitivity analysis was performed and its consequences on a common scenario

of a finite Al alloy plate with a central crack was studied. The present work studies examples of

fatigue crack growth data to understand its scatter and to estimate the sensitivity of the fatigue

life assessment to these material parameters. As a case study, the scatter of different Al alloys will

be presented, considering a common scenario of a through crack on a plate. Taking into account

the different data sets, the difference in the fatigue life was evaluated. Scatter and differences on


104

the material parameters related to the fatigue crack growth have considerable impact on this

determination. This study suggests that the fatigue crack growth data should be used in a cautious

way and using probability of failure functions since the materials have inherent scatter and the

external factors that affect the fatigue crack growth in real structures are not always completely

known.


105

#159

Structural analysis of a cross car beam using finite element models

André Pinto

1, S.M.O. Tavares

2, J. M. A. César de Sá

1, P.M.S.T. de Castro

1

1Faculty of Engineering of the University of Porto, Porto, Portugal {[email protected],

[email protected], [email protected]}

2 Institute of Mechanical Engineering and Industrial Management (INEGI), Porto, Portugal,

[email protected]

Abstract The present paper concerns the use of PAM-CRASH, a finite element analysis

solver, to assess the performance of a mass production vehicle cross car beam (CCB) under

impact conditions (crashworthiness) and its modal analysis (NVH assessment). The

available data at the beginning of the present study consisted of the structure CAD file and

performance requirements stated by the OEM for NVH. No technical information was

available concerning crashworthiness. Taking into account these limitations, it was decided

to adapt the requirements for other mass production cars of the same category, as regards

dynamic loading, including g-forces resulting from deceleration. Although the

unavailability of published results for this particular cross car beam model prevents a

comparison of the present results, the trends and order of magnitude of the several analyses

performed are within expectation for this type of product. Concerning modal analysis, the

steering column first natural frequency had a percent deviation from the design target of

5.09%. The other requirement of the NVH assessment regarding a 5 Hz minimum interval

between first vehicle CCB mode and the first mode of the steering column was indeed

achieved. This study is a further confirmation of the interest of numerical modeling as a

first step before actual experimental testing, saving time and money in an industry that has

seen an enormous increase of the demand for new models in the last decade.


106

Figure 1 – CCB structure.


107

Session 5B

TUE, 14:15-15:30

Room Berlin

TOPIC: Testing

Chair: Daniel Kujawski


108

#176

Evaluation of Semi-Ellipsoidal Wall Thinning on Back Surface of Plate

by Direct-Current Potential Difference Method

Naoya Tada1, Manabu Nohara

2

1Graduate School of Natural Science and Technology, Okayama University,

3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530, Japan,

[email protected]

2 Graduate School of Natural Science and Technology, Okayama University

Abstract Local wall thinning is one of serious problems in aged power generating plants. As

the thinning grows inside the pipes, it is difficult to detect and evaluate it from the outer surface

of pipe. Various non-destructive techniques, such as ultrasonic and eddy current testings, have

been developed for this purpose. The direct-current potential difference method (DC-PDM) is

also a suitable non-destructive technique to monitor the initiation and growth of wall thinning.

Figure 1 shows an example of the distribution of normalized potential difference, V/V0, in the

central area of 70[mm] 70[mm] on the surface of large flat plate with a semi-ellipsoidal thinning

of 60[mm] (total length) 60[mm] (total width) 15[mm] (depth) on the back surface, where V

is the potential difference between a pair of probes and V0 is that without wall thinning. This result

was obtained by an electric field analysis under a uniform current supplied. Higher increase in the

potential difference was found near the wall thinning part, which shows the possibility of wall

thinning detection by this method. As the geometry of wall thinning (i.e., length, width and depth)

affects or determines the potential difference distribution, it is considered that the evaluation of

wall thinning geometry is also possible. In this study, an evaluation method of wall thinning

geometry by DC-PDM is proposed and the results are discussed.

Wall thinning

z

y

No

rmal

ized

po

ten

tial

dif

fere

nce

V/V

0

Over1.2151.17

1.1351.09

1.0451

0.785

Under

0.830.8750.91

0.955

Uniform current


109

Figure 1 – Distribution of normalized potential difference in the central area on the surface

of flat plate with semi-ellipsoidal local wall thinning on the backside.


110

#113

Internal residual stresses of tungsten-CFRP hybrid laminates

M. Kanerva1, E. Sarlin

2, M. Wallin

1, M. Laulajainen

1, T. Brander

1, O. Saarela

1

1Aalto University, School of Engineering, Department of Applied Mechanics, P.O.Box 14300,

FI-00076 Aalto, Finland; email: [email protected]

2Tampere University of Technology, Department of Material Science, P.O.Box 589, FI-33101

Tampere, Finland

Abstract Hybrid laminates are outstanding solutions for applications where superior

mechanical performance must be combined with functional requirements. A laminated system

consisting of thin tungsten and carbon-fibre-reinforced plastic (CFRP) layers is a light, stiff and

strong concept, which also works as an efficient radiation shield, for spacecraft enclosure

structures. An unfortunate consequence of the concept is the formation of residual stresses during

manufacture due to the thermal expansion mismatch between tungsten and CFRP.

In this study, we analyse internal residual stresses due to thermal expansion (contraction) of

tungsten-CFRP hybrid laminates. Our study includes experimental work and 3-D simulations

using finite element methods:

a) Strain measurements during a cure cycle – analysis of the residual stress development for

elevated temperature curing.

b) Simulation of thermal residual strains in a hybrid laminate – analysis of the effects of initial anomalies (curvatures, Ri) and comparisons to the experiments.

First of all, the residual stresses are very high due to the high Young’s moduli (410 GPa for

tungsten and 215 GPa for the CFRP) and anisotropy. Secondly, since the tungsten layers are

extremely thin (50 µm), the simulation of the laminate distortion during the cool down period is

sensitive to micrometre-scale anomalies in the initial flatness of the tungsten layer. Our results

show that already a small initial anomaly in the tungsten layer flatness

(Ri > 3 × specimen length) affects the residual strains (change in the longitudinal strain 40%) and

distortions significantly – making it demanding to predict dimensional accuracy and interlaminar

strength in the final structures.


111

Figure 1 – On the left hand side: experimental strain measurements during curing;

on the right hand side: simulation of the effects of curvatures on residual stresses.


112

#130

Dynamic parameters and dissipative capacity of a pultruded FRP

spatial structure

Giosuè Boscato1, Salvatore Russo

2

1IUAV University of Venice, Dorsoduro 2206, 30123 Venezia, Italy, [email protected]

2IUAV University of Venice, Dorsoduro 2206, 30123 Venezia, Italy, [email protected]

Abstract This research proposes some evaluations on the behavior factor q of pultruded FRP

strut and tie spatial structure (Figure 1). The proposed calculation procedure is based on the

dynamic identification data of existing frame made of pultruded FRPs (Fiber Reinforced

Polymers). The determined experimental dynamic parameters were used to calibrate a numerical

finite element model employed under the hypothesis of kinematic equivalence to evaluate the q

factor considering the elastic-brittle behaviour of FRP material. The dissipative capacity of

structure was assigned to the global geometric configuration - frame with concentric diagonal

bracings - through the strength hierarchy criteria locating the dissipative zones in the tensile

diagonals. The analysis was carried out considering some typological variations to investigate the

variability of the behavior factor q.

Figure 1 - View of all-PFRP structure


113

#181

Sloshing forces in a 3D liquid waste storage tank under harmonic wave

excitation

V.S. Sanapala1, T. Selvaraj

1, B.M. Ananda rao

1, A. Ravisankar

1, K.Velusamy

1 and

B.S.V. Prasad Patnaik2

1Department of Atomic Energy, IGCAR, Kalpakkam, India.

E-mail: [email protected] 2Department of Applied Mechanics, IIT Madras, Chennai, India.

E-mail: [email protected]

Abstract

Liquid storage in containers is a problem of practical interest in a variety of engineering

applications. The fluid stored in the tank is more prone to external excitations such as

earth-quakes, wind loads etc. There is a possibility of wall buckling and damage to the

base of liquid storage tanks during such events. In case of nuclear applications, the storage

tanks containing radioactive liquids must be designed safe against such eventualities.

In this paper, A study is carried out on the dynamic response of the liquid under sloshing

in a 3D tank against external harmonic excitation. Accordingly, an incompressible N-S

equation based solver is employed using volume of fluid (VOF) method to track the free

surface interface. As a validation problem, 2D tank is modeled first and the free surface

displacement time histories for both resonant and non-resonant cases are compared with

experimental results available from the results. Good agreement between simulations and

corresponding experiments indicates that the present numerical scheme is able to predict

the nonlinear behavior accurately. The scheme is then applied to a 3D tank, studied the

free surface height, hydrodynamic pressures at different locations and also the dynamic

forces acting on the walls of the tank.

mailto:firstauthor_id@domain_name.org


114

Figure 1 - The problem domain of interest for a 3-d rectangular tank


115

Session 6A

TUE, 16:00-17:15

Room Lisboa

TOPIC: Models

Chair: Francisco Melo


116

#163

Application of the Strain-Based FAD to Failure Assessment of Surface

Cracked Components

Igor Varfolomeev1, Michael Windisch

2, Gerben Sinnema

3

1Fraunhofer IWM, Freiburg, Germany; [email protected] 2MT Aerospace AG, Augsburg, Germany

3European Space Agency, ESA/ESTEC, Noordwijk, The Netherlands

Abstract In this study, finite-element analyses (FEA) are carried out to explore the

applicability of the strain-based failure assessment diagram (SB-FAD) to the evaluation of surface

crack behaviour in components under displacement controlled boundary conditions. The major

expectation is that the SB-FAD may potentially be useful in the damage tolerance assessment of

a composite overwrapped pressure vessel (COPV) during autofrettage loading. For comparison

purposes, cracked plates subjected to uniaxial tension are also considered. The following

geometries are analyzed:

− Plates with semi-elliptical cracks. The ratio of the crack depth to plate thickness is varied

between 𝑎/𝑡 = 0.1 and 0.5, whereas the crack aspect ratio is assumed to be 𝑎/𝑐 = 0.2 or 1, where

𝑐 is a half crack length.

− COPV under internal pressure containing a shallow semi-elliptical crack with 𝑎/𝑐 = 0.2 and

𝑎/𝑡 = 0.1 or a through-wall crack with the length equal to 10 times the wall thickness.

Three materials exhibiting different strain hardening capacity are investigated: AA2219-T87

(high strain hardening), Inconel 718 (medium strain hardening) and Ti-6Al-4V (low strain

hardening).

The numerically calculated J-integrals are compared to respective analytical estimates based

on the SB-FAD, using both Option 1 and Option 2 approximations. It is found that the analytical

approach yields conservative and rather accurate J-integral estimates (especially, Option 2) for

plate models, whereas the Option 2 may underestimate the crack driving force for surface cracks

in the COPV, as shown in Figure 1.


117

Figure 1 – J-integral vs. internal pressure for a semi-elliptical crack in COPV liner made

of Ti-6Al-4V alloy


118

#164

Theoretical and experimental model for the analysis of a cardan cross

Eugen Avrigean1

1 Emil Cioran Street, Sibiu, 550025, România [email protected]

Abstract

The paper presents a mathematical, numerical and experimental analysis of a component element

of the cardan joint, namely the cardan cross, which is one of the most loaded elements in the

whole assembly. The numerical and experimental analyses use state-of-the-art software packages

(Cosmos), Instron testing machines as well as state-of-the-art data acquisition devices. It is sought

to determine and verify the strain values using several methods.

Figure 1 - The numerical and experimental analyses

mailto:%20%20%[email protected]


119

#165

Multiscale Simulation Strategy for Low-Velocity Impact on FRP

C.S. Lopes1, F. Naya1, C. González1 and P.P. Camanho2

1IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe (Madrid), Spain

[email protected] 2DEMec, Faculdade de Engenharia, Universidade do Porto, Portugal

Abstract Low-velocity impact events occur with some frequency on composite applications

such as airplane components. From ground operations to unavoidable birds, there is a range

of situations where an aircraft outer component may be subjected to unexpected impact loads.

The damage produced in such cases is mostly in the form of delaminations which are not

easily noticeable through routine naked eye inspections. However, the spread of these

delaminations over wide areas of the structure may severely compromise the residual

compressive strength of the structure, possibly even below the limit load for which it was

initially designed. Therefore, the ability to predict the impact damage resultant from impact

events likely to happen is of high importance to the aeronautical industry.

This paper proposes a systematic strategy to determine the mechanical behaviour of

composite materials under low-velocity impact using a multiscale numerical approach. A

virtual design/testing strategy that takes into account the physical mechanisms of damage at

the different length scales is developed and validated, so the influence of the microstructure

and loading conditions can be taken into account rigorously. The multiscale approach

describes systematically the material behaviour at different length scales from ply to laminate.

One of the advantages of this bottom-up multiscale approach is that changes in the properties

of the constituents (fibre, matrices), the fibre architecture or laminate lay-up can be easily

incorporated to provide new predictions of the macroscopic behaviour of the composite. At

mesoscale level, a three-dimensional continuum damage model for the simulation of intraply

damage phenomena is used. Delamination is simulated by making use of cohesive surfaces.

The use of structured meshes, aligned with fibre directions allows the accurate capturing of

matrix cracks, and their interaction with the development of delaminations. Element erosion

and the application of friction allow the simulation of fibre splits and their entanglement

which results in the permanent indentation of the impacted specimen.


120

Figure 1 Multiscale strategy for LVI simulation: a) Matrix tensile damage for AS4/8552

under transverse tension. Simulation of 40J impact on a 32-ply composite AS4/8552

laminate sample (longitudinal stresses (σ11) are shown)


121

#115

Structural Deformation Measurements by Image Block Matching

Algorithms

Graça Almeida1, Fernando Melício

1, José Manuel Fonseca

2

1Lisbon Superior Engineering Institute, Rua Conselheiro Emídio Navarro 1, 1959-007 Lisbon,

Portugal, [email protected], [email protected]

2Faculty of Science and Technology, 2829-516 Caparica, Portugal, [email protected]

Abstract

The traditional methodology used in civil engineering measurements requires a considerable

amount of equipment and a very complex procedure especially if the number of target points

increases. The general idea behind digital image processing techniques is to calculate the

displacement field, see Figure 1, without contact sensors, using a normal consumer camera. With

this information it is possible to calculate the strain field and other complementary information.

Using image-processing techniques it is possible to measure not only a few points but the whole

area of interest.

Figure 1– Displacements in y-axis, where the dark area is the area with large displacements

This paper presents the DIM (Digital Image Measurements) software that automatically

computes the displacement field based on block matching algorithms. Two different algorithms

are used: the Adaptive Rood Pattern Search and the Rood Pattern - Particle Swarm Optimization.

The system setup is very simple involving a simple photographic camera (no camera calibration

is required), a spot light and a computer that automatically captures images at regular intervals.

For better results, the specimen must be covered with a random or regular pattern. The pattern

can be prepared with an underlying layer of white matt ink on top of which black ink is sprayed.

The DIM software uses a photo sequence taken during the load test and based on this information

analyzes a particular region of interest (ROI). After the test has been completed different ROIs

can be chosen and analyzed independently. This is only possible with this methodology, which

allows greater reduction of cost and time since it does not require the test repetition for new

achievements even analyzing a number of points substantially than the traditional instrumentation

approach in Civil Engineering tests. This approach can be directly transposed to any other field

that requires displacement measurements such as mechanical strength tests, fatigue analysis and

many others.


122

In this paper we will present the results of the application of our methodology to different

sequences of images taken during real stress tests with special emphasis on the software system

specifically developed for this purpose.


123

Session 6B

TUE, 16:00-17:15

Room Berlin

TOPIC: Testing

Chair: Paulo Tavares


124

#155

Evaluation of mixed-mode I+II fatigue crack propagation in steels

assisted by DIC

A.L.L. Silva1,2

, J. Xavier3, Diogo Carvalho.4, A.M.P. Jesus

2,4, A.A. Fernandes

1,2

1Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 400 4200-465

Porto, Portugal. [email protected]

2Institute of Mechanical Engineering (IDMEC).

3Institute of Mechanical Engineering and Industrial Management (INEGI).

4Universidade de Trás-os-Montes e Alto Douro (UTAD)

Abstract The fatigue crack propagation in mechanical/structural components occurs frequently

under mixed mode I + II conditions. The evaluation of the stress intensity factors (KI, KII) under

these circumstances may be performed using both numerical, experimental or hybrid methods.

More recentlty, significante advances in the field of the Digitial Image Correlation (DIC) open

new possibilities for the experimental methods, in particular for the evaluation of stress intensity

factors directly from the measured displacement fields. The paper presents a methodoly to

measure combined mixed mode I and II stress intensity factors, using DIC, on modified CT

specimens. Firstly the crack path was assessed using DIC and resulting path was compared with

direct optical observations performed on the specimens oposite surface (see Fig. 1). After that,

mixed mode stress intensity factors (KI, KII) were computed using a displacment extrapolation

technique.

Figure 1 – Crack path assessment using Optical Microscope and DIC.


125

#156

Virtual Sensors for SHM using isogeometric piezoelectric finite

elements

Artur Szewieczek1, Christian Willberg

2, Michael Sinapius

3

1German Aerospace Center (DLR), Lilienthalplatz 7, 38108 Braunschweig,

[email protected]

2 German Aerospace Center (DLR), Lilienthalplatz 7, 38108 Braunschweig,

[email protected]

3 Technische Universität Braunschweig, IAF, Langer Kamp 6, 38106 Braunschweig,

[email protected]

Abstract

Guided waves like Lamb waves can be excited and received easily by PZT patches in plates

and plate-like structures. They propagate over large areas with small damping and interact with

structure discontinuities such as impacts. Therefore, this principle can be used for impact

detection and localization.

The wave propagation can be very complex due to reflections, refractions or mode

conversions. A simulation of the exact wave behavior in complex components poses a hard

challenge due to non-exactly known material parameters and high requirements on computing

power. Furthermore, simulations have to be validated with experiments.

At the German Aerospace Center an imaging technique for guided wave investigations was

developed. Here, a combination of bonded actuators for wave excitation and air coupled ultrasonic

scanning technique for plate scanning is used for wave propagation research. The measurement

data contains all information of wave interaction with the real structure and can be used for

different imaging methods like B-Scans or video animations of wave propagation.

The measurement data can also be used for advanced tasks like virtual sensors. In this

technique measured displacements of the structure surface are used as stimulation of a virtual

sensor which can be designed by software and positioned within available data field. For the

calculation of sensor signals an isogeometric finite element model is used. The virtually bonded

layer of the virtual piezoceramic sensor interpolates with non-uniform rational B-Splines

(NURBS) the measured nodal data for each time step. This interpolation corresponds to a

displacement boundary condition and is used to calculate the electrical potential at the free surface

of the sensor. Isogeometric finite elements have, due to their higher polynomial ansatz, a better

convergence and can be distorted. Therefore, they allow better results than standard FEM

applications.


126

#157

On Monitoring of Mechanical Characteristics of Hot Rolled S355J2

Steel

Donka Angelova, Rozina Yordanova, Alexander Georgiev, Svetla Yankova

University of Chemical Technology and Metallurgy – Sofia, 8 St. Kliment Ohridski, Blvd., 1756

Sofia, Bulgaria, [email protected]

Abstract Hot rolling technology for producing sheets from a low-carbon steel, Steel S355J2,

used in the Bulgarian Metallurgical Plant STOMANA Industry SA is under investigation. A

newly introduced normalization process in this technology is an important step that leads to

avoiding of traditional heat treatment, improving of steel mechanical characteristics, increasing

of production efficiency, all resulting in high quality final products [1, 2]. On the basis of the final

mechanical rolled-sheet characteristics - yield strengths, Re, ultimate tensile strengths, Rm,

absorbed energies in impact tests, K, and elongations at fracture - some energy-stress

(MNLQQ1M1N1L1) and energy-stress-elongation (MVZQQ1M1V1Z1) spaces have been plotted,

respectively shown in Fig.1a and in Fig.1b. These spaces can be used as an instrument for general

evaluation of the applied rolling technology and for prediction of steel-sheet mechanical

behaviour under exploitation conditions [3, 4]. Transition from one space to the other can be done

through the plotted stress-elongation area NVZL.


127

a. b.

Figure 1 - Steel S355J2: a. Energy-stress Space; b. Energy-stress-elongation Space

References:

1. Dieter G. E. 1988. Mechanical Metallurgy. McGraw-Hill Book Company

2. Angelova D., Kolarov D., Philipov К. and Yordanova R. 2009. Metal Science and

Metal Forming Handbook, Part 5, edited by Angelova D., р.348. Sofia, Bulgaria:

Academic publishing house “М. Drinov” (in Bulgarian).

3. Dowling N. 2006. Mechanical Behavior of Materials. Engineering Methods for

Deformation, Fracture, and Fatigue. Prentice Hall

4. Angelova D., Yordanova R., Georgiev A. and Yankova S. 2013. Investigation of

Possibilities for Improving Mechanical Characteristics of a Low-Carbon Hot Rolled

Steel. Scientific Proceedings. Year XXI, No 2 (139), pp. 249-253.


128

#160

The use of optical scanning methods for testing of thin oxide films

deposited on rough steel substrates

Janusz Jaglarz

Institute of Physics, Cracow University of Technology, ul. Podchorążych 1, 30-084 Kraków,

Poland

e-mail: [email protected]

Abstract

The paper presents techniques for the measurement of optical thin film profiles

determined from optical profilometry (PO) and scanning spectroscopic

ellipsometry(SSE). The presented methods were used for non-destructive testing of

structural integrity of thin films and hard coatings. The first method allows a map of the

local reflectance of the small surface areas (102 mm2), the second method allows to

determine changes in the polarization light beam of reflected from the thin films. These

methods measure the surface topography of the films in long space wavelengths (of the

order of a few mm2 to several cm2), thereby complementing the measurements made

using atomic force microscopy (AFM). To determine the thickness, and the refractive

index in model fitting the semi-coherent optical theory of reflection from rough films was

used . The combined PO and SSE investigations have been used to determine the root

mean square (rms) roughness and autocorrelation length of films and surfaces. The

Fourier transform analysis of layer images was applied to determine correlation between

upper and lower film surface obtained from PO and SSE study. In work we show results

of PO and SSE study performed for oxide layers (La0,6 Sr0,4)(Co0,2 Fe0,8)O3 deposited

on croffer steel by the use laser ablation method.


129

Session 7

WED, 11:30-13:00

Main A

TOPIC: Testing

Chair: Chris Rodopoulos


130

#108

System for Fuel Elements Inspection of Nuclear Research Reactor by

the Sipping Method

Rogerio Rivail Rodrigues, Amir Zacarias Mesquita

1 Nuclear Technology Development Centre/Brazilian Nuclear Energy Commission

(CDTN/CNEN)

Abstract The Centro de Desenvolvimento da Tecnologia Nuclear - CDTN (Belo Horizonte)

is a research institution of the Brazilian Federal Government (Comissão Nacional de Energia

Nuclear). Its mission is nuclear research for peaceful purposes. In its facilities there is a nuclear

research reactor type TRIGA Mark I, manufactured by General Atomics Co. The reactor is

operational since November 1960. The CDTN TRIGA core configuration containing 59

aluminum clad fuel elements, and 4 stainless steel clad fuel elements. Due to legal safety

requirements imposed by the Brazilian regulatory body, it has become necessary to examine all

fuel elements that form the reactor core, to verify its structural integrity as regards the possibility

of leakage of fission products due to defects in the cladding. With this objective is being

developed and will be implemented a methodology specifies to check the fuel elements by

employing the technique of the sipping test. So it was designed a device for carrying out this test

in the TRIGA reactor fuel elements of CDTN. The system is in the final stages of manufacturing.

This article describes the current stage of the research project. A container where the fuel elements

will be inserted was built. One test will be conducted using an unirradiated fuel (unburned)

element. This test is intended to show the feasibility of the proposed system (Fig 1). The next step

is the inspection of all existing fuel elements in the core. In this case, care must be taken due to

ionizing radiation emitted by fuels. The expected result is confirmation that the fuel elements are

in excellent condition, taking into account the new security protocols, ensuring the continued use

of the reactor safely.


131

Figure 1 – assembly of the receptacle for the nuclear fuel of the sipping inspection method


132

#111

Remote monitoring of an elevated water reservoir using optical fiber

technology

Paulo Antunes1, Humberto Varum2, Paulo André3 1 1Instituto de Telecomunicações - Aveiro and Departamento de Física da Universidade de

Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal 2 2Departamento de Engenharia Civil da Universidade de Aveiro, Campus de Santiago, 3810-

193 Aveiro, Portugal e 3 3Instituto de Telecomunicações - Lisboa and Department of Electrical and Computer

Engineering, Instituto Superior Técnico,

Abstract In this work we demonstrate the remote monitoring of an elevated water reservoir,

located at the University of Aveiro Campus, using an all optical fiber technology. The acceleration

sensor uses fiber Bragg gratings, as element sensor, and the acceleration signal is measured at the

Instituto de Telecomunicações facilities, where the measurement equipment is located. The

optical signal travels from the measuring point through the university campus optical fiber

network to the Instituto de Telecomunicações, which is 1658 meters distant from the reservoir.

Among the advantages of the remote monitoring are the possibility to make measurements during

harsh environmental conditions in a completely safe mode, such as strong winds, and the

possibility to continuously monitor the structure and its response, allowing to, in real time, infer

about its structural performance and safety. Figure 1 shows the monitored structure and the

acceleration data collected remotely (for a wind speed of 8.0 m/s with a 290º North direction. The

natural frequencies of the structure, resulting from the FFT application to the measured data, are

also displayed in the figure. The sensor sensitive directions are aligned with the longitudinal (50º

North) and transversal (320º North) directions of the structure.

The implemented system allowed the remote monitoring of the structure under extreme wind

speeds that would make the onsite measurements problematic, due to safety reasons.


133

Figure 1 – a) Monitored structure; b) and d) the remotely collected acceleration data for

de accelerometer sensitive directions; and c) and e) the frequencies spectra

with the estimated natural frequencies


134

#114

Thermal Fatigue Behaviour of Polyamides used in Intercoolers

D. Faustino1, V. Infante

1, L. Neves

2

1Instituto Superior Técnico, ICEMS, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa,

Portugal

2João de Deus & Filhos SA, Estrada dos Arados 5, 2135-113 Samora Correia, Portugal,

[email protected]

Abstract

The present study aimed to develop techniques towards characterizing the static mechanical

behaviour of three different polyamides used in intercoolers and then the structural fatigue

behaviour of the polyamide selected for a specific industrial application.

Since this is a highly complex component subject to various loadings, an analysis methodology

comparing two different strands was adopted; one with an experimental character and the other

based on a numerical simulation known as Finite Element Analysis, FEA.

The experimental research was based in thermal tensile and fatigue tests carried at high

temperatures.

The tensile tests were carried out at room temperature, 150ºC, 190ºC and 210ºC. In order to

avoid dispersion of results were tested 3 specimens of each polymer at different temperatures.

Thermal fatigue tests were carried out at room temperature and 210ºC in a servo hydraulic

machine coupled with a furnace. The specimens were tested until fracture or up to 105 cycles

concerning the industrial application and a constant amplitude loading with stress ratio, R=0.1

and frequency of 10 Hz. Fatigue data is presented in the form of S-N curves.

The experimental results indicated that the thermal life of the polyamides was reduced with

increasing test temperature.

To ensure the reliability of the numerical model, the mechanical characterization was studied

in detail, either as regards the approximation of the hyperelastic model to the experimental work,

as to determine the range of deformations for which the model is numerical stable, since the lack

of stability can strongly affect the numerical solution. This characterization was based on a

numerical simulation, FEA, considering properties from production process. These properties

were obtained using an interface between an injection molding computer-aided engineering

software and a software of finite element analysis.


135

#116

Long term monitoring of a high-speed railway bridge: thermal

behaviour

Manuel Cuadrado1, Daniel Gómez del Pulgar

1, Emma Moliner

1

1 Fundación Caminos de Hierro para la Investigación y la Ingeniería Ferroviaria, Madrid,

Spain. [email protected]

Abstract In the framework of the VIADINTEGRA research project funded by both the

Spanish Ministry of Economy and Competitivity and the European Union, the Villanueva del

Jalón viaduct is being permanently monitorized, in a view to improve its reliability assuring

structural safety and optimize repairing and maintenance operations, by means of a continuum

evaluation of its structural health condition.

Villanueva del Jalón viaduct is a six-span box girder high-speed railway bridge of double track

located at Calatayud, Spain. It is composed by a prestressed concrete box girder of constant

section with 6 spans and 5 piers, with a total length of 250 m. A long-term monitoring system was

designed and installed, including accelerometers, clinometers, strain gauges, displacement and

thermal sensors. Two of the main functions of the monitoring system are: i) the analysis of track-

bridge interaction phenomena by controlling seasonal evolution of the deck and track

displacements and strain; ii) the evaluation of the evolution of modal dynamic parameters under

seasonal variations caused by temperature.

Since April 2012 the permanent sensors have been recording statistical values of all the

measured parameters and once per month 6 hours of dynamic data with a sampling frequency of

200 Hz. In this work the main results after the analysis of the measurements are presented, and

the time evolution of both dynamic behaviour and track-bridge interaction are discussed.

The measured data have been compared with the results predicted by finite element models of

the viaduct. The track-bridge interaction model has been updated with the long-term

measurements of deck and the track displacements and strain. The dynamic model has been

updated with the results of a short-term dynamic test, showing a reasonably good correspondence

in terms of natural frequencies and Modal Assurance Criterion values of the mode shape.

-290

-270

-250

-230

-210

-190

-170

-150

5 10 15 20 25 30 35

Deck temperature (ºC)

Re

l. D

isp

l. s

lid

ing

-fix

ed

ra

ils

on

ex

pa

ns

ion

jo

int

(mm

)

Average daily values

Average daily values december 12

Twice the standard

error of the estimate

(a)

5

10

15

20

25

30

De

ck

te

mp

era

ture

[ºC

]

(b)

-1.0%

-0.5%

0.0%

0.5%

1.0%

1.5%

Sep'12 Oct'92 Nov'12 Dec'12 Apr'13 May'13 Jul'13 Sep'13

Ch

an

ges i

n n

atu

ral

freq

uen

cie

s

Average 5 first vertical modes


136

Figure 1 – (a) Correlation between deck temperature and relative displacement sliding-fixed

rail on expansion joint; (b) Seasonal variation of bridge natural frequencies and deck

temperatures


137

Session 8A

WED, 14:15-15:30

Room Lisboa

TOPIC: Testing

Chair: José Xavier


138

#119

Keying Effect During Fracture of Stainless Steel

Farej Ahmed Emhmmed

Assistant Prof. of Materials Science

Al Zaytona University

Tripoli / Libya

[email protected]

Abstract:

Fracture of duplex stainless steels (DSS) was investigated in air and in 3.5 wt % NaCl solution.

Tow sets of specimens were heat treated at 475°C for different times and pulled to failure either

in air or after kept in 3.5% NaCl with polarization of -900 mV/ SCE . Fracture toughness testing

was performed using a clip gauge and the direct current potential drop (DCPD) tow techniques

to monitor the crack propagation process. The crack tip open displacement (CTOD) was evaluated

for both methods. Discrepancy was observed between the experimental data and the

computational ones. Fracture took place in general by ferrite cleavage and austenite ductile

fracture in transgranular mode. Literature was able to expect the crack tip open displacement ,

experimental data , only within a certain range of the material hardness. Some microstructural

features played a role in " blocking" the crack propagation process leading to lower the CTOD

values specially for specimens aged for short times. Unbroken ligaments/ austenite were

observed at the crack wake. These features may exerted a bridging stress , blocking effect , at

the crack tip giving resistance to the crack propagation process.

Keywords:

Stainless steels, Fracture toughness, 475°C ,embrittlement, CTOD, DCPD.


139

#120

Non-destructive methodology based on magnetic flux density

measurement, in the reversibility domain region, to follow stainless

steel embrittement

Edgard M. Silva1, Jorge H.R. Silva

1, Ana L.S. Souza

1, Neilor C. Santos

1 ,Josinaldo P.

Leite2, Mickael M. Rodrigues

2

1Federal Institute of Paraíba, Av. 1o de Maio, 720, CEP 58015-430, João Pessoa, Pb, Brazil,

[email protected], [email protected] [email protected], [email protected]

2 Federal University of Paraíba, Cidade Universitária, CEP 58051-900, João Pessoa,

Brazil, [email protected], [email protected]

Abstract T Non-Destructive Testing is used to assess the presence of discontinuity that may

affect the integrity of materials in service. This is the main reason why they are used in

maintenance to detect defects. In this study, Hall Effect sensors are used to develop of a non-

destructive methodology, able of follow material embrittement. Magnetic flux density, with value

in the reversibility domain regions, was applied into the material. For this purpose, it was chosen

a material in which temperature of study microstructural transformations would occur due to the

single-phase decomposition, so the effect of this transformation will modify the Hall voltage

signal. The duplex stainless steel UNS-S31803 was chosen for its characteristics in temperatures

below 525°C. At 475oC, this steel has the highest rate of embrittlement, due to the formation of

α' phase. Samples of this steel were aged to times up to 100 hours at 475oC. Measurements of

magnetic flux density based on the Hall voltage values were performed, as well as hardness

measurements, impact toughness and fracture surface analyses by scanning electronic

microscopy. The results show that magnetic flux density measurements are able to follow

formation the 475oC embrittlement, as can be seen in Figure 1. The methodology shows promising

to follow the nano structure α' phase that cause the deceased of impact energy.








140

Figure 1 – Impact energy and magnetic lux density as a function of the aging time at 475oC.


141

#127

Analysis of the magnetic field integrity of electric machine and

construction structure

Stanisław Radkowski1, Szymon Gontarz

2, Przemysław Szulim

2

1Warsaw University of Technology, Institute of Vehicles, Poland

[email protected]

2 Warsaw University of Technology, Institute of Vehicles, Poland

Abstract The paper presents a description of the measuring device, method of measurement

and description of the results of research on testing stands aimed at attracting new sources of

information about the technical condition devices and constructions.

Still looking for new methods determine the status of the effort of steel structures, detect early

stages of damage in order to increase the safety of these facilities. The results of the tests carried

out using the device for the visualization of the x, y, z of the magnetic flux in space. The device

is based on a sensitive magnetic flux sensor, fluxgate type which has been integrated with inertial

sensors to determine the angular orientation of the magnetometer. To determine the full spatial

orientation, vision base method was used. The application of a Fluxgate sensor to register the

magnetic flux has allowed observe not only the quasi static field changes, but also the dynamic

changes in a field around the full operating speed of the electric motor.

For the analysis of such a large amount of data, an important issue is the visualization of the

results. Built for the needs of the experiments the application allows to track changes of the major

parameters of the flux in the space around the truss steel structure, typical of large halls as well

around BLDC motor. The application also allows observe changes in the parameters of the

magnetic field in space with information about the instantaneous position of the shaft of the

electric motor, what is important for diagnostics. The paper presents a description of the

measurement system with a focus on the basic problem occurring with fusion signals from the

selected sensors. Paper presents the measurements results from two different types of

experiments. One study focused on the magnetic flux integrity around the truss subjected to cyclic

load changes. In this paper is presented a description of phenomena of impact the state of the

construction strain on the magnetic flux around it. The second type of experiments concerned the

observation of magnetic flux around the BLDC motor, where successively various mechanical

defects were set. The paper presents an attempt of connection of selected faults introduced to the

object and the characteristic parameters of the magnetic flux. The work ends with a summary of

the authors, with particular attention to the usefulness of the system in the diagnosis and its further

development.


142

#137

SIF determination with Digital Image Correlation

Paulo J. Tavaresa, Frederico Silva Gomes

a, P.M.G.P. Moreira

a

INEGI – Institute of Mechanical Engineering and Industrial Management, University of Porto,

4200-465 Porto, Portugal

Abstract

Hybrid methods, wherefore numerical and experimental data are used to calculate a critical

parameter, have been used for several years with great success in Experimental Mechanics and,

in particular, in Fracture Mechanics. This letter reports on the development of a hybrid

methodology for the determination of the stress intensity factor (SIF) parameter, which entails

combining experimental and numerical procedures to compute the SIF based of linear elastic

fracture-mechanics concepts.

The strain field around the crack tip was obtained experimentally with the digital correlation

method, as depicted in Figure 1 and stresses were assessed thereof, applying linear theory of

elasticity. The obtained data was used as input to the implemented over-deterministic numerical

algorithm and the stress intensity factor solutions for different crack lenghts were the obtained.

Those results were validated with SIF solutions drom the Dual Boundary Element Method

(DBEM) and show an excellent agreement.

Figure 1 – DIC strain field on the MT specimen


143

Session 8B

WED, 14:15-15:30

Room Berlin

TOPIC: Materials

Chair: Peter Horst


144

#151

Characterization of nickel alloy 600 with ultra-fine structure processed

by severe plastic deformation technique (dpi)

W.A. Monteiro

a,b, S.L.V. Silva

a, L.V. Silva

a, A.H.P. de Andrade

a, L.C.E. Silva a

(a) CCTM – Instituto de Pesquisas Energéticas e Nucleares (IPEN)

Av. Lineu Prestes, 2242 – Cidade Universitária, CEP 05508-900, São Paulo – SP

(b) CCH – Universidade Presbiteriana Mackenzie (UPM), São Paulo – SP

[email protected]

Abstract

High strength nickel based alloys are used in a multitude of advanced systems where

lightweight, high power density mechanical power transmission systems are required.

Components such as gears, bearings and shafts could be made significantly smaller and

more durable if a major improvement in nickel based alloy mechanical properties could

be achieved. A significant refinement in grain size (includes nano level) is thought to be

a promising method for achieving fundamental improvements in mechanical properties.

Grain size is known to have a significant effect on the mechanical behavior of materials.

One of the most favorable methods of achieving extreme grain refinement is by subjecting

the materials to severe plastic deformation. The principal microstructural variations in

superalloys are the precipitation amount and morphology, grain size and the distribution

of carbide precipitation (Cr7C3 and Cr23C6) that could reduce the mechanical properties

of the alloys. This work shows optical and transmission electron microscopy analysis and

also hardness data after severe plastic deformation (pure shear stress) and some thermal

treatments.

Key-words: nickel alloy 600, severe plastic deformation (SPD), optical microscopy,

electron microscopy, hardness test.


145

#134

The effect of size, amount and surface treatment of micro particles of

cork on the toughness of a brittle epoxy

A.Q. Barbosa1, Lucas F.M. da Silva2, J. Abenojar3, Miguel A.V. de Figueiredo2, A.

Öchsner4

1IDMEC, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal

2 Department of Mechanical Engineering, Faculty of Engineering, University of Porto,

Rua Dr. Roberto Frias, 4200-465, Porto, Portugal

3Materials Performance Group. Materials Science and Engineering Dept.

Universidad Carlos III de Madrid. Av. Universidad, 30. 28911-Leganés,

Spain

4 Griffith School of Engineering, Griffith University (Gold Coast Campus), Building

G39 Room 2.22, Parklands Drive, Southport Queensland 4214, Australia

Abstract Epoxies are the most common structural adhesives due to their good mechanical,

thermal and chemical properties. However, the structure of these thermoset polymers also

causes brittleness, with a low resistance to the initiation of cracks and their propagation. The

inclusion of particles (nano or micro) is a method to improve the mechanical properties such

as toughness of structural adhesives [1]. Structural adhesives are known for their high strength

and stiffness but also for their low ductility and toughness. There are many processes

described in the literature to increase the toughness, being one of the most common the use of

rubber particles [2]. In the present study, natural micro particles of cork are used with the

objective to increase the toughness of a brittle epoxy adhesive. The idea is for the cork particles

to act like as a crack stopper leading to more energy absorption [3,4]. This fact occurs because

cork presents a remarkable combination of properties (low density, low cost and sustainability

of the raw material). The influence of the cork particle size, amount and surface treatment

were studied. Particles of cork ranging from 125 to 250 µm and 38-53 µm were mixed in the

adhesive Araldite 2020 from Huntsman. The amount of cork in the adhesive was varied

between 0.25 and 1% in volume. To improve the adhesion between cork particles and adhesive

it was used a plasma surface treatment. The toughness of the adhesive was assessed through

toughness measurements with three-point bending specimens (SENB). The Taguchi method

was used to evaluate the influence of the variables presented (size, amount, treatment).

[1] - L.F.M. da Silva, A. Öchsner, R.D. Adams (ed.), in “Handbook of Adhesion Technology”,

Springer-Verlag, Heidelberg (2011)


146

[2] – A.J. Kinloch, “Adhesive in Engineering”, Proc. Instn. Mech Engrs, 211 Part G, (1997) 307-

335

[3] - A. Q. Barbosa, L.F.M da Silva, A. Öchsner, J. Abenojar, J. C. del Real, J Adhesion, 88 (4-6)

(2012) 452-470

[4] – A. Q. Barbosa, L.F.M da Silva, A. Öchsner, Proc. Inst. Mech. Eng. L J (2013) doi:10.1177/1464420713493581


147

#169

Corrosion performance of corrugated stainless steels in mortar

partially immersed in chloride solution for 8 years

A. Bautista, S.M. Alvarez, E.C. Paredes, F. Velasco


Carlos III de Madrid. Av. Universidad, 30. 28911 Leganés, Spain

Abstract The high alkalinity of concrete creates an environment that protects steel against

corrosion. However, the life expectancy of concrete structures is affected by corrosion of steel

reinforcements, due to an aggressive attack of chloride ions or carbonation. The presence of

chloride in the environment increases the risk of pitting corrosion in these steels. Stainless steels

are more corrosion resistant to chloride than traditional carbon steel reinforcements, and their use

in reinforced concrete structures is increasing. There are scant studies on the corrosion behaviour

of corrugated stainless steels embedded in concrete or mortar, especially when compared to the

large number of studies published using simulated pore solutions.

In this research, mortar samples were reinforced with 5 different corrugated stainless steels

(duplex and austenitic) and tested for 8 years in non carbonated environments under partial

immersion in 3.5% NaCl. Corrugated carbon steel was used as reference. The monitoring during

the exposures was carried out with corrosion potential (Ecorr), as shown in Figure 1 and

electrochemical impedance spectroscopy (EIS) measurements. Figure 1 shows the excellent

performance of all steels but low nickel austenitic S20430 steel. The exposure in 3.5% NaCl

causes a very low-intensity corrosive attack in S20430 samples after 7 years of exposure. After 8

years, the reinforced mortar samples were anodically polarized to obtain more information about

the pitting resistance of the passive layers formed under the different conditions. These long-term

mortar tests confirm that traditional austenitic and duplex corrugated stainless steels are an

excellent option to assure the durability of reinforced structures in chloride contaminated media.

S32205 duplex stainless steel shows excellent behavior, even under high anodic polarizations.


148

Figure 1 – Ecorr evolution of the partial immersed mortar samples during the 8-year

exposure. The evaluation of the corrosion risk following ASTM 876 criteria has been included.


149

#110

Fatigue damage evolution and life prediction for metastable austenitic

steels under consideration of martensite phase transformation

Huang Yuan

Institute for Aero Structural Integrity

Tsinghua University, Beijing 100084, PR China

Surface treatment is an important step in manufacturing critical mechanical parts. The

improvement of fatigue behavior of the mechanical part is realized just due to compressive

residual stresses and distortions of the surface material. Quantifying effects of surface treatment

in fatigue life improvement requires detailed understanding of the mechanical behavior of the

material with strong distortion and variation of the residual stresses in the surface layer material.

The stainless steel SS348 is metastable austenite material, its crystallographic structures can

transform to martensite phase under plastic deformations. Due to martensite phase the stainless

steel behaviors significantly differently from the austenitic steel, both in plastic deformation and

failure. Using known models to establish a continuum mechanics model for quantifying effects

of surface treatment needs detailed understanding of evolution of microstructure and meso-

mechanical behavior of the distorted material. Especially, phase transformation under severe

compressive deformation is less investigated in the past.

The present work dedicates to identify a plasticity model for SS348 under severe plastic

deformations, especially under compressive deformations, and to clarify effects of the pre-

strains to material failure under monotonic and cyclic loading. Based on extensive experiments,

the plasticity model under consideration of the martensite transformation should be applied to

predict fatigue life of the compressive deformed specimens and to quantify effects of the

compressive strains to material failure evolution.


150

#162

Biodegradable composite thermoplastics used in interior parts of

aerospace and automobile products

André F.C. Vieira 1, Rui M. Guedes

2, Volnei Tita

1

1Aeronautical Engineering Department, São Carlos School of Engineering, University of São

Paulo, São Carlos, São Paulo, Brazil, [email protected], [email protected]

2INEGI, LABIOMEP, Mechanical Engineering Department, Faculty of Engineering of

University of Porto, Porto, Portugal, [email protected]

Abstract There are many biodegradable polymers commercially available, which combined

with natural fibers (such as sisal, banana, coconut, hemp) or particulates (such as cork, sawdust),

can be used to produce a great variety of composite interior parts for automobiles, trains and

airplanes in order to obtain “green products”, following eco-design philosophies. Reliability of a

product may be defined by its ability to fulfill requirements during time. Biodegradable

composites can present short term performances similar to conventional composites. Although

the performance of a biodegradable composite decreases during time, mainly due to hydrolytic

degradation of the biodegradable polymer matrix, the interior parts should support the design

requirements, during all its life cycle. However, the mechanical behavior of biodegradable

polymers along its degradation time, in the presence of water or humidity and temperature, is still

an unexplored subject. In this work, it is considered a three-dimensional viscoplastic model. It

enables to simulate the monotonic tests of a biodegradable structure loaded under different strain

rates, and also the hysteresis effects during unloading-reloading cycles at different strain levels.

Furthermore, a parametric study is presented, showing the evolution of the material model

parameters during the hydrolytic degradation, and a sensibility study is carried out. The

investigated model was able to predict well the experimental results of a blend of polylactic acid

and polycaprolactone (PLA-PCL) in the full range of strains until rupture during hydrolytic

degradation.


151

Figure 1 - Experimental results of non degraded PLA-PCL fiber,

and prediction via viscoplastic Bergström-Boyce model

a) monotonic tensile test at two displacement rates (500 and 15mm/min),

b) cyclic tensile test


152

Session 9A

WED, 16:00-17:15

Room Lisboa

TOPIC: Testing

Chair: Sérgio Tavares


153

#139

Fatigue Crack Growth Measurement Automation

Paulo J. Tavares1; Nuno Viriato Ramos

2 and P.M.G.P. Moreira

3

1 LOME - Optics and Experimental Mechanics Laboratory

Institute of Mechanical Engineering and Industrial Management, University of Porto, Portugal

- [email protected] [email protected], [email protected]

Abstract This letter describes the ongoing work at our laboratory on the implementation of

an automated vision system for fatigue crack growth measurement. The system is based on a

dedicated illumination system with grazing incidence and optimized feature extraction by

morphological image processing and continuous calculation of the da/dN parameter for

adaptation of the optimal time interval for image registration.

Measurement of fatigue crack growth [1] has been a fastidious but necessary activity for the

Mechanical Engineering experimentalist. The experimentalist’s experience and sensitivity on

fatigue tests is essential for determination of the reading time intervals, in particular towards the

end of the experiment, when failure to perform the necessary readings may irrevocably jeopardize

the entire trial. Furthermore, an important source of variability is, reportedly, the evaluation of

the crack length [2]. The progression of automatic vision algorithms and morphological image

processing as well as the constant improvement on CCD technology and camera price plunge, no

longer justify holding back the development of automated systems that are competent in

performing optical measurements [3].

Figure 1 - Camera and lighting device in operation.

[1] Florent Mathieu, François Hild, Stéphane Roux: “Image-based identification procedure of

a crack propagation law”, Engineering Fracture Mechanics (2012), in press;

[2] Clark W. G., Hudack Jr. S. J.: “Variability in fatigue crack growth testing”, Journal of

Testing and Evaluation 3 (1975), p. 454–76;


154

[3] P. M. G. P. Moreira, A. M. P. de Jesus, A. S. Ribeiro, P. M. S. T. de Castro: “Fatigue crack growth in friction stir welds of 6082-T6 and 6061-T6 aluminium alloys: A comparison”,

Theoretical and Applied Fracture Mechanics 50 (2008), p. 81-91.


155

#140

Contactless defect detection using two emerging Optical Methods for

NDT of composite structures - Thermography and Shearography

Jaime M. Monteiro, H. Lopes, Mário A.P. Vaz

1Instituto de Engenharia Mecânica e Gestão Industrial - INEGI, [email protected]

2Instituto Superior de Engenharia do Porto - ISEP, [email protected]

3Faculdade de Engenharia da Universidade do Porto - FEUP, [email protected]

Abstract Optical techniques for nondestructive testing & evaluation (NDT&E) are used to

access the presence of defects within the material, without affecting its physical integrity. Among

the main optical methods of NDT&E, Shearography and Thermography either passive or active,

have shown great potential in the detection and evaluation of defects. These techniques have

received considerable industrial acceptance and they can be applied to most materials. When

compared, they present advantages and disadvantages and can complement each other and thus

constitute NDT&E tools with high capacities. In this article, the principles and the methods of

testing of these two techniques are reviewed. A comparative analysis of both techniques and their

application in the inspection of composite structures with defects is done by addressing the

strengths and limitations of each other.


156

Figure 1 - Inspection results on a composite plate with several defects obtained with

Shearography and lock-in-Thermography.


157

#144

Novel Non-Destructive Testing techniques for structural integrity

F. Nascimento1, T. Santos

2, C.C.C.R. de Carvalho

3,4, R. Miranda

2, L. Quintino

3

1 Instituto Superior Técnico, Universidade Técnica de Lisboa, Avenida Rovisco Pais 1, 1049-

001 Lisboa, Portugal, email: [email protected]

2 Faculdade de Ciências e Tecnologia da universidade Nova de Lisboa, Monte da Caparica,

Portugal

3 Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal

4 Institute of Biotechnology and Bioengineering, Centre for Biological and Chemical

Engineering, Department of Bioengineering, IST

Abstract The present paper outlines recent developments and respective validation of

innovative non-destructive testing (NDT) techniques aimed at different types of applications and

defect detection. NDT techniques allow for an analysis of the structural integrity of the different

mechanical parts. These methods are very efficient in the identification of different defects that

can compromise the structural integrity in the different applications. The growing demands of

industry lead to a need for faster and more precise methods for the identification of these defects.

Recent developments have allowed the development of a new NDT technique that can be used

for the detection of microdefects. This technique uses a bacterial suspension where the fluorescent

bacteria will adhere to the surface defects when an electrical or magnetic field is applied. This

process has the potential to detect defects of 2.9 μm depth in steel. Eddy currents can be

complemented or even substituted by electrical conductivity measurements to detect changes in

the microstructure of metal with higher precision. Ultrasonic techniques have been in the forefront

of NDT developments for more than a decade and the Phased Array techniques have proven its

capabilities to detect defects in different circumstances, as plastic pipelines and composite

structures.

This work will focus on the basis of these technologies and its potential for industrial

application. A comparison study has been made with existing technologies and validation in

laboratory tests and industry cases is presented.


158

#149

Structural monitoring of wind turbine blades

Silvina Guimarães1, Mário A.P. Vaz

1,2, Jaime M. Monteiro

1, Nuno Viriato Ramos

1, José

Carlos Matos1, Miguel Marques

1

1 INEGI –Institute of Mechanical Engineering an Industrial Management,

[email protected], Rua Dr. Roberto Frias, nr. 400, 4200-465, Porto, Portugal

2Department of Mechanical of the Faculty of Engineering of University of Porto

Abstract

Wind turbine blades inherently subjected to loads with provenience in the atmospheric flow

and are, in fact, one of the elements with a shorter life-cycle. Their monitoring with the purpose

of anticipating damage and potentially correct is, although not that often, hence a key aspect in

the successful operation of a wind turbine.

In this work a structural monitoring system for wind turbine blades is described. Using Bragg

sensors in optical fibers to obtain the strain on the blades and GSM delivering signal, this device

allows controlling the structural integrity in real time. With attained data it is possible to access

or even anticipate damages, as well as, to perform a life cycle assessment of this component in a

more reliable way.

Figure 1 – Installation of the system and sensors in the wind turbine



159

Session 9B

WED, 16:00-17:15

Room Berlin

TOPIC: Materials

Chair: Daniel Kujawski


160

#170

Fire resistant coatings for polymeric matrix composites

F. Velasco, S. Guzmán, A. Bautista, M.A. Martínez


Carlos III de Madrid. Av. Universidad, 30. 28911 Leganés, Spain

Abstract Fibre reinforced polymer composite materials are being used for different structural

applications. However, composites are vulnerable to fire in two key aspects: their resin content

may ignite and the flames spread over the surface and the degradation of the resin due to the heat

of a local fire exposure that is weakening the composite structure. Until a few years ago, the

inflammability could be reduced with halogenated compounds, now prohibited in many countries

due to the release of toxic gases during the fire. Some solutions can be found in intumescent

paints.

Coatings with thermal barrier properties seem very suitable for fire protection of composite

materials, which is the main barrier preventing composites from the construction market, in spite

of their excellent mechanical properties. In this work, tailored coatings with hollow particles have

been developed and applied to glass fibre reinforced epoxy composites to improve the behaviour

against to fire. Their effect on thermal conductivity has been measured, and the manufactured

coatings reduce heat transmission to the substrate.


161

Moreover, and due to their good fire reaction, the fire resistance under loads has also been

evaluated. Figure 1 shows an example of the loads measure with time when fire is applied to

uncoated and coated composite materials. Coated samples were able to keep the material good

conditions for at least 15 min.

Figure 1 – fire effect on loaded (0.2 kN) composites both uncoated and coated: change of

force with time.

0

20

40

60

80

100

120

0 100 200 300 400 500 600 700 800 900 1000

Time (s)

F (

%)

COATED 1

COATED 2

PMC 1

PMC 2


162

#177

Evaluation of Advanced Materials in Aircraft Structure

Martin Bugaj, Andrej Cíger

1Martin Bugaj, assoc. prof., University of Žilina, Air Transport Department, Slovakia,

[email protected]

2Andrej Cíger, PhD. Student, University of Žilina, Slovakia

Abstract The main goal in almost all daily activities is safety. Many kinds of researches and

development try to find out how to produce things easily with appropriate amount of safety. We

have to take into account that every construction used is potentially in some conditions damaged

and could collapse. This situation is in some cases dangerous and could be fatal. Researchers have

to produce constructions which are still safe even during failure and could resist minor damage

and equipment is still usable in operation or will not suffer any damage until their determined

lifetime. Especially in aviation new trends push materials development and technologies forward

and it is absolutely normal when half of aircraft construction is made by composite material. This

kind of material is used in extreme conditions and can resist heavy loads. It is very light which is

in aviation very important and needed. Main problem appears in setting save lifetime for this

material or how to deal with damages during operations.

This paper shows some kinds of degradation processes in materials such as delamination in

composites used in construction aiming to special types of fibers. Increasing of costs in aircraft

production despite efficiency improvements in technologies and manufacturing operations, can

be attributed primarily to the increased use of more expensive materials and structural parts and

assemblies. The tendency in aircraft production has been a growing use of high-cost composites,

titanium parts and advanced materials to maximize weight efficiency.

Aircraft composite material is in expanding usage continuously. Fiber reinforced composites

find their utilization in the rapidly broadening field of applications. Some composite types can be

considered as structural materials for usage at elevated temperatures. Ideally they should be

lightweight, chemically and thermally stable, possessing good mechanical properties and cheap.

Next the paper presents the possibility of using basalt fibers in composite structure, its

techniques of production, physical and mechanical characteristics and analysis of mechanical

capabilities. Basalt, a natural mineral material, environmentally-friendly, gradually becomes a

new substitute in the composite group. There is a lack of research on basalt fibers; in fact, few

studies on basalt fiber as reinforcement material in resin have been published.


163

#179

Electromagnetic shielding enclosure built on metallic lightweight

structure for aerospace EMI protection applications - Experimental

tests and numerical simulation -

Mihai Enache1, Dan Fostea

2, Adina Otilia Boteanu

2, Cristian Puică2

1Military Equipment and Technologies Research Agency – METRA, Information Systems &

Communications Test Evaluation Scientific Research Center, Aeroportului Street no. 16,

Bucharest, Romania, [email protected]

2Military Equipment and Technologies Research Agency – METRA, Information Systems &

Communications Test Evaluation Scientific Research Center, Bucharest, Romania,

[email protected], [email protected],[email protected]

Abstract Two of the major issues of the aerospace applications, where sensitive electronic

equipments must be safely operated with respect to aircrafts building design and

installation restraints, are the density of the electromagnetic interferences (EMI) and the total

weigh of the electrical and electronic equipments. Our first concern was to address the problem

of EMI and emission security (EMSEC). The classical protection solutions consist of standard

electromagnetic shielded enclosures, designed as the product chassis, which do not met the

requirements for aerospace applications because implies several disadvantages like: ergonomics,

transportability, maintenance, interoperability and versatility. In order to find an applicative

solution for these problems we carried our work to design and develop a special experimental

model (ExpM) for EMI/EMSEC protection. ExpM consists of a modular lightweight materials

shielding enclosure that can be adapted to all and each equipments maintaining their

performances and functionalities. After the process of testing and optimizing some materials,

conductive coatings and fabrics applied to different types of dielectric substratum by deposition

and multi-layer techniques, we selected the optimal ones and we defined requirements for the

Electromagnetic Shielding Enclosure (ESE) built on metallic lightweight structure. In this paper

we present the numerical simulation and analysis of the structure behavior concerning different

dropping impacts and collisions. The impact performance of Faraday enclosure is a major concern

of a new design.

The analysis procedure helped us to comply with minimum mechanical requirements,

evaluates yield stress and deformation characteristics of products and will provide the necessary

data for ExpM design and execution process. After the execution phase, using all intermediate

numerical simulation and experimental test results, ExpM will be tested as a product, both for

complying with electromagnetic shielding and mechanical requirements according to

EMI/EMSEC national, European and NATO standards.



mailto:[email protected],[email protected]


164

#183

Influence of Titanium, Niobium and Aluminium addition on

microstructure and mechanical properties of Ferritic Stainless Steel

welds

1Nabil Bensaid,

1Mohamed Farid Benlamnouar,

1 Amar Boutagane

1 Welding and NDT Research Centre (CSC), BP 64, Road of Dely Brahim, Chéraga, Algiers,

Algeria

E-mail :[email protected]

Abstract ferritic stainless steel steels are associated with many problems during the welding

process. These problems are the martensite formation and grain growth, causing a reduction of

ductility and toughness. For these reasons, until recently, the application of this group steels is

limited in welded structures. The aim of the present study is to investigate the influence of the Ti,

Nb and Al on the microstructure and mechanical properties of welds of 1,2 mm thick AISI 430

ferritic stainless steel sheets produced by GTA welding. The microstructures of the welded joints

were investigated by the optical microscopy (OM), the mechanical properties included hardness

and tensile strength was investigated, the fracture surfaces of the tensile specimen were examined

by scanning electron microscopy (SEM). From this investigation, it is observed that the grain

growth in fusion zone is limited when the titanium content above 0.2%, and lead to a fine grain

structure, equiaxed grains morphology and superior tensile of weld metal, when compared with

conventional welding.

Figure 1 - Martensite formation and grain growth in fusion zone of AISI 430 ferritic

stainless steel weld

http://www.google.dz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCwQFjAA&url=http%3A%2F%2Fwww.csc.dz%2F&ei=5ar_UounK9HS4QTPi4CACA&usg=AFQjCNEw2g3kMdBz-krnysD5J0U8M70SCA&sig2=NOFaz2CQKGLKcZylv2uCAg&bvm=bv.61535280,d.bGE



165

#161

Designing and optimization of new composite pallet

Alexander Janushevskis1, Anatolijs Melnikovs

2

1Prof. Dr.sc.ing., Riga Technical University, 6, Ezermalas, Riga, Latvia, [email protected]

2Dr.sc.ing., Riga Technical University, [email protected]

Abstract Metamodeling is generally recognized efficient approach for the optimization problems. In our case it is used for shape optimization. Due to development of CAD/CAE software and

advanced metamodeling techniques such approach has become highly effective and popular in

recent years. The references to the non parametric approximation methods are commonly given to solve deterministic problems. For non-deterministic optimization problems, such as in

proposed case of composite pallet structure (Figure 1) that must account for uncertainties, the

optimization should be based on double loop approaches where the uncertainty propagation is

recursively performed inside the optimization iterations. Often the uncertainty estimation for the given point is based on metamodel, thus allowing reduction of computational time but introducing

additional bias in the estimates. In such approach a single loop kriging based method for

minimizing the mean of an objective function is proposed: the simulation points are calculated in order to simultaneously propagate uncertainties, i.e., estimate the mean of objective function, and

optimize this mean. This approach is realized in the original code KEDRO for design of

experiments, analysis and multiobjective robust optimization.

The FE-model of the composite pallet is considered and solved accurately as multi-ply

shell structure. The fiber-reinforced polymer material mechanical properties and two

main operation cases of the loaded pallet are taken into account during deterministic

structural optimization procedure. Next the same problem is considered as non-

deterministic taking into account possible uncertainties of the pallet supporting

conditions. In both cases shape is defined using CAD based NURBS curves (Figure 1).

Appropriate shapes of the stiffness ribs are found for best performance of the structure.

Sensitivity analyses for probabilistic performances are given. As a result of optimization,

the competitive design of composite pallet is developed, that could meet requirements of

the modern automated distribution systems, including superior strength and weight ratio,

nestable design concept, increased service life, better corrosion and impact resistance.


166

Figure 1 - 3D model of composite pallet with obtained optimal shapes of stiffness ribs (left)

and NURBS parameterization (right)


167

Index

A. Barbini, 91 A. Bautista, 83, 148, 161 A. Carvalho, 45 A. Karanika, 45 A. Öchsner, 146 A. Ravisankar, 87, 98, 114 A.A. Fernandes, 125 A.H.P. de Andrade, 145 A.L.L. Silva, 125 A.M.P. Jesus, 125 A.Q. Barbosa, 146 Aaron Warren, 70 Adina Otilia Boteanu, 164 Agnieszka Boto-Probierz, 80 Alexander Georgiev, 127 Alexander Janushevskis, 166 Amar Boutagane, 165 Amir Zacarias Mesquita, 131 Ana C.F. Silva, 43, 78 Ana L.S. Souza, 140 Anatolijs Melnikovs, 166 André Correia, 62 André F.C. Vieira, 151 André Pinto, 106 Andrej Cíger, 163 António Bettencourt Ribeiro, 89 António Silva, 100 Artur Szewieczek, 126 B. Beaussir, 85 B.M. Ananda rao, 114 B.M. Ananda Rao, 98 B.M. Anandarao, 87 B.S.V. Prasad Patnaik, 114 Bruno Henriques, 66 C. Barile, 93 C. Casavola, 93 C. Correa, 73 C. Dong, 85 C. González, 120 C. Leitão, 47 C. Pappalettere, 93 C.C.C.R. de Carvalho, 158 C.S. Lopes, 120

Carlos Mota, 81 Christian Willberg, 126 Cláudia Carneiro, 60 Cristian Puică, 164 Cristina Castejón S., 102 D. Faustino, 135 D. Peral, 73 D.M. Rodrigues, 47 Dan Fostea, 164 Daniel F.O. Braga, 43, 78 Daniel Gómez del Pulgar, 136 Daniel Michalik, 80 Diogo Carvalho, 125 Donka Angelova, 53, 127 E. Sarlin, 111 E.C. Paredes, 148 Edgard M. Silva, 140 Emma Moliner, 136 Eugen Avrigean, 119 F. Nascimento, 158 F. Naya, 120 F. Pierron, 96 F. Velasco, 83, 148, 161 F.F. Duarte, 44 Farej Ahmed Emhmmed, 139 Fernando Cunha, 81 Fernando Melício, 122 Filipe Silva, 66 Francisco Góis, 66, 67 Francisco Q. de Melo, 103 Frederico Silva Gomes, 78, 143 G. Pappalettera, 93 Gaurav Rajput, 87 Gerben Sinnema, 117 Giosuè Boscato, 113 Graça Almeida, 122 H. Lopes, 156 Huang Yuan, 150 Humberto Varum, 133 Igor Varfolomeev, 117 Ivo Lopes, 62 J. Abenojar, 146 J. Bitenieks, 51


168

J. Carstensen, 91 J. Ferreira, 69 J. Lu, 77 J. M. A. César de Sá, 106 J. Morais, 96 J. Vatavuk, 57 J. Xavier, 96, 125 J. Zicans, 51, 55 J.A. Porro, 73 J.C. Reis Campos, 62, 64 J.F. dos Santos, 91 J.L. Ocaña, 73 Jaime M. Monteiro, 103, 156, 159 Janusz Jaglarz, 129 Janusz Majta, 76 Jerzy Myalski, 80 João Custódio, 89 João Sampaio-Fernandes, 66 Joaquim Gabriel, 100 John W. Labadie, 71 Jorge H.R. Silva, 140 José Carlos Matos, 159 José Manuel Fonseca, 122 Josinaldo P. Leite, 140 Juan Carlos P., 102 K.Velusamy, 114 Kim C. Long, 71 Krzysztof Muszka, 76 L. Neves, 135 L. Quintino, 158 L. Ruiz de Lara, 73 L.B. Cavalcanti, 64 L.C.E. Silva, 145 L.V. Silva, 145 Lucas F.M. da Silva, 43, 146 Lucie Nováková, 46 M Portela, 67 M Sampaio-Fernandes, 67 M. de Freitas, 44 M. Díaz, 73 M. Kanerva, 111 M. Laulajainen, 111 M. Nurgaliev, 45 M. Pantoja, 83 M. Parente, 69 M. Seabra, 69

M. Wallin, 111 M.A. Martínez, 161 M.A. Sampaio-Fernandes, 64 M.I. Costa, 47 M.J. Ponces, 64 Malgorzata Sopicka-Lizer, 80 Manabu Nohara, 109 Manuel Cuadrado, 136 Manuel Ferreira, 81 Marcin Kwiecien, 76 Margarida Sampaio-Fernandes, 66 Maria Helena Fernandes, 66 Maria Helena Figueiral, 66 María Jesús G., 102 Mário A.P. Vaz, 59, 60, 62, 64, 100, 103,

156, 159 Martin Bugaj, 163 Martin Kadlec, 46 MH Figueiral, 67 Michael Sinapius, 126 Michael Windisch, 117 Michal Krzyzanowski, 50 Mickael M. Rodrigues, 140 Miguel A.V. de Figueiredo, 78, 146 Miguel Marques, 159 Mihai Enache, 164 Mohamed Farid Benlamnouar, 165 N. D. Alexopoulos, 45 N. Huber, 77 N. Kashaev, 45, 77 Nabil Bensaid, 165 Naoya Tada, 109 Nathalie Valle, 80 Neilor C. Santos, 140 Nelson Silva, 81 Nuno Neves, 60 Nuno Viriato Ramos, 59, 60, 62, 154, 159 O. Saarela, 111 P Fonseca, 67 P.Kuzhir, 51 P.M.G.P. Moreira, 43, 44, 48, 78, 100,

143, 154 P.M.S.T. de Castro, 44, 104, 106 P.P. Camanho, 120 Paulina Graca, 76 Paulo André, 133


169

Paulo Antunes, 133 Paulo J. Tavares, 48, 143, 154 Pedro Couto Viana, 62 Pedro Gomes, 66 Przemysław Szulim, 142 R. Berzina, 55 R. Maksimov, 55 R. Merijs Meri, 51, 55 R. Miranda, 158 R. Natal, 69 Ralitsa Pavlova, 53 Raul Fangueiro, 81 Rogerio Rivail Rodrigues, 131 Roman Růžek, 46 Rozina Yordanova, 53, 127 Rui M. Guedes, 151 S. Guzmán, 83, 161 S. Maksimenko, 51 S. Riekehr, 45 S.A.L. Pereira, 57 S.L.V. Silva, 145 S.M. Alvarez, 148 S.M.O. Tavares, 104, 106 S.Z. Hao, 85 Salvatore Russo, 113 Sanatana Maharana, 98 Satish Kumar Velaga, 87

Shayan Eslami, 48 Silvina Guimarães, 159 Stanisław Radkowski, 142 Sunil Kumar Gupta, 98 Svetla Yankova, 53, 127 Szymon Bajda, 50 Szymon Gontarz, 142 T. Brander, 111 T. Czerwiec, 85 T. Grosdidier, 85 T. Ivanova, 51 T. Santos, 158 T. Selvaraj, 87, 98, 114 Tomasz Pawlik, 80 V. Infante, 44, 135 V. Kalkis, 55 V.C. Pinto, 64 V.S. Sanapala, 114 Volnei Tita, 151 W. Cruz, 96 W. Mark Rainforth, 50 W.A. Monteiro, 57, 145 William S. Duff, 71 Xianyan Zhou, 95 Xin Feng, 95 Y. Samih, 85 Zoser Kalengayi T., 102

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