ACHIEVING DESIRED STIFFNESS OF FLEX BEAM USING SHAININ … · 2018-09-01 · ACHIEVING DESIRED STIFFNESS OF FLEX BEAM USING SHAININ METHODOLOGY 1 Shashikumar C B, 2 Amaresh Kumar

ACHIEVING DESIRED STIFFNESS OF FLEX BEAM USING

SHAININ METHODOLOGY

1Shashikumar C B,

2Amaresh Kumar D, 3Shrishail Kakkeri,

4Syed Zain Ahmed

1Assistant Professor, Department of Mechanical Engineering, Sri Venkateshwara College of

Engineering,Bangalore, Karnataka, India

2Assistant Professor, Department of Mechanical Engineering, Sri Venkateshwara College of

Engineering, Bangalore, Karnataka, India

3Professor, Department of Mechanical Engineering, Sri Venkateshwara College of


4Student, Department of Mechanical Engineering, Sri Venkateshwara College of


Abstract

Main purpose of this paper is to observe the intensity of effectiveness of a modest but

not very habitually used method known as the Shainin Methodology for shorten the

implementing Six Sigma.Composite materials are created by combining two or more

constituent materials with a view to improve the properties or to create materials with the

desired properties. Composites due to their light weight, stiffness strength and high specific

thermal properties are widely used for aircrafts and aerospace applications. Recent

developments in this field have led to substantially improved fuel economy and extended

flight range.

The quality of composite parts mainly depends on the following:

1. Fiber volume ratio

2. Fiber resin properties

3. Fiber orientation

4. Curing parameters (Temperature, pressure, vacuum)

5. Processing techniques

International Journal of Pure and Applied MathematicsVolume 119 No. 18 2018, 2853-2868ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

2853

As the performance of the composite is shown to be dependent on the curing parameters

i.e. curing pressure, temperature, and vacuum, it is important to determine the best curing

temperature.

The cure cycle shown above is the standard cure cycle for monolithic components. The

temperatures and pressure shown in the above graph are standard used during the

manufacture of any component. This project studies the variation of the tensile and flexural

strength of parts manufactured by varying the curing temperatures.

In this work, five specimens or laminations have been taken and cured at different

temperatures including the standards curing temperatures (i.e.135°C)and the variation of

tensile and flexural strength of the laminates is studied.

The optimal curing temperature is sought to be determine by conducting these studies:

thereby saving time and energy for each cure cycle

Keywords:Shainin methodology, Composite materials, etc.

1.BASIC INTRODUCTION ON FLEX BEAM

A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This

allows the helicopters to take off and land vertically, to hover, and to fly forward, backward,

and laterally. These attributes allow helicopters to be used in congested or isolated areas

where fixed-wing aircraft and many forms of VTOL (Vertically takeoff and landing) aircraft

cannot perform

The tail rotor blade is a smaller rotor mounted so that it rotates vertically or near

vertically at the end of the tail of a traditional single-rotor helicopter. The tail rotor‟s position

and distance from the center of gravity allow it to develop thrust in the same direction as the

main rotor„s rotation, to counter the torque effect created by the main rotor.

The tail rotor drive system consists of a shaft powered from the main transmission and

a gearbox mounted at the end of the tail boom. The drive shaft may consist of one long shaft

or a series of shorter shafts connected at both ends with flexible couplings that allow the drive

shafts to flex with the tail boom. The gearbox at the end of the tail boom provides an angled

drive for the tail rotor and may also include gearing to adjust the output to the optimum

rotational speed for the tail rotor, measured in rotations per minute (rpm). The tail rotor pylon

International Journal of Pure and Applied Mathematics Special Issue

2854

may also serve as a vertical stabilizing airfoil, to improve the power requirement for the tail

rotor in forward light. The tail rotor pylon may also serve to provide limited anti torque

within certain airspeed ranges, in the event that the tail rotor or the tail rotor flight controls

fail. About 10% of the engine power goes to the tail rotor.

Flex Beam is an integral part of tail rotor blade. The tail rotor blade(TBR) is

essentially is an un-ducted fan with blades that vary in pitch to vary the amount of thrust they

produce. The blade utilizes a composite material construction, such as a carbon and glass

fiber composite. The blades use a symmetrical airfoil and their pitch angle can be adjusted

both positive and negative to produce thrust in either direction.

Fig. 1.1: 3D view of tail rotor drive system

Fig. 1.2: Fiberglass-Epoxy Flex Beam

A fiberglass-epoxy flex beam extends from tip to tip of each opposed blade pair, carrying the

blade centrifugal forces so that none of the centrifugal loading is carried by the hub. Two


2855

pairs of opposed rotor blades are used, and the opposed blades are interconnected by the flex

beams. These flex beams are bolted to the hub. The flex beam is clamped between the hub

plates and the bolts are tightened.

2. LITERATURE REVIEW

Stefan Steiner and Jock MacKay are both Associate Professors in the Statistics and

Actuarial Science Department of the University of Waterloo. They are also active consultants

who have worked with organizations from a wide range of Industriesincluding Automotive,

Telecommunications, Aerospace, govt. and more.

John S. Ramberg, Professor Emeritus, University of Arizona and quality consultant, is

a fellow of ASQ, ASA and IIE. He holds a B Electrical Engineering (Industrial Engineering).

His work experience includes Procter & Gamble, Motorola, and Hughes Space Systems. He

is editor emeritus of The Journal of Quality Technology, and member of the editorial board.

The selected details about constituent materials are shown in table.

Table 2.3 Properties of constituent materials.

Parameter Carbon Fiber

(Fabric) Epoxy Resin

Density 1.65 g/cm3 1.13 g/cm3

Areal weight 240 Grms/m2 ----

Thermal

conductivity

coefficient

15.0 W/mK 0.22W/mK

Carbon fiber reinforced epoxy composites were fabricated by hand lay – up with a

variation of carbon content, the variation of fiber contents was achieved using different

number of carbons layers with the same total thickness of the specimen. The epoxy resin was

cold – cured under ambient conditions (-21degree C) and after curing process was thermally

hardened at 50degC for 24hrs. The specimens were 100mm by 100mm square and ~ 6.2mm

thick.


2856

3. METHODOLOGY FOR QUALITY IMPROVEMENT

3.1 Introduction on Shainin methodology for Quality Improvement.

The Shainin methodology is the name given to a problem solving system, with its

associated strategies and tools, developed by Dorian Shainin, and widely used and promoted

in the manufacturing sector. The Shainin System was developed for and is best suited to

problem solving on operating, medium to high volume processes where data are cheaply

available, statistical methods are widely used.In any problem, there is a dominant cause of

variation in the process output that defines the problem. This presumption is based on an

application of the Pareto principle to the causes of variation. There is a risk that multiple

failure modes contribute to a problem, and hence result in different dominant causes for each

mode Shainin methodology uses a process of elimination called progressive search, to

identify the dominant causes.

FIGURE-3.1.1The Shainin system for quality improvement.

3.2The problem solving algorithm

The Shainin methodology steps for problem solving are given in Figure3.1.1the

algorithm is divided into two parts, the Diagnostic and Remedial Journeys. In the diagnostic

journey, the problem is defined, the measurement system is assessed, and the dominant cause

of variation is identified and verified. In the remedial journey, the effect of the dominant

cause is eliminated or reduced by changing the product design, the process, or the control

plan.


2857

The purpose of the first stage of the algorithm is to quantify the magnitude ofthe

selected problem. To do this, we monitor the output of the process using an appropriate

sampling scheme.

The second stage in the Shainin methodology algorithm (see Figure 3.1.1) involves

the quantification and establishment of an effective measurement system. Without a good

measurement system, it is difficult to learn about and improve the process, and the

measurement system itself may be home to the dominant cause of the problem.

The goal of the third stage of the Shainin algorithm is to generate clues about the dominant

cause. This is the progressive search. At this stage, another key emphasis in Shainin is to

„„talk to the parts‟‟ we use observational rather than experimental plans as much as possible.

Shainin methodology makes heavy use of observational plans such as

a) Multivari investigations

b) Stratification

c) Group comparasion

d) Scatter

e) Isoplot

The basic concept of Shainin Red X can be summarized by 6 statements:

• Variation exists in all processes.

• Understanding and reducing variation are keys to success.

• In the real world nothing happens without a mason.

• There is always a Red X

• Finding and controlling the Red X is the only way to reduce variation.

• Executing a progressive search by “talking to the parts” is the best way to find the Red X.

The Shainin Red X methodology consists of about 30 techniques and tools. They are

known as well as newly developed techniques which create the comprehensive stepwise

system for process improvement.

Shainin problem solving roadmap is called

FACTUAL

F-Focus

A-Approach

C-Converge


2858

T-Test

U-Understand

A-Apply

L-Leverage

No problem can be solved without knowledge of the output and related processes,

symptoms of the failure as well as difference between good and bad parts. This is ensured by

approach which is described as “talking to parts”, set of techniques used to converge the

problem as elimination of suspects, comparison between good and bad parts, finding

extremes.

Focus

Leverage probable events

Project Definition

Estimate the impact

Approach

Green Y Identification and

Description

Developmentof Investigation

Strategy

Measurement System

Verification

Converge

Converging on the Red X

Compare best and worst case

Red X Candidate

Identification

Test

Risk Assessment

Red X Confirmed by Trial

Understand

Green Y to Red X

Relationship Understood

Optimization of interactions

Customer needs translated to

limits

Appropriate Tolerance Limits

Established

Apply Corrective Action


2859

Implemented and Verified

Procedures updated

Green Y monitoring

Project Benefits and Cost

Savings

Leverage

Read Across Red X Control

Savings Calculated

Lessons Learned

3.3selections of Shainin Tools

By tool, both the plan of the investigation and the recommended analysis method.

Shainin system tools are generally statistically simple plans with small sample sizes that

make extensive use of graphical displays and non-parametric tests that can be performed by

hand.However, that the non- parametric analysis methods are weak and non- intuitive. While

we are strongly in favour of graphical approaches, with today‟s widespread availability of

statistical software, ease of calculation is not an issue and we recommend supplementing the

graphs with straightforward standard analyses. For some of the Shainin tools,

a) Isoplot

b) Multivari

c) Component searchand variable search

d) Group comparison

e) B v/s Cand factorial experiments

f) Tolerance parallelogram

g) Precontrol

4. Design, fabrication and testing of the helicopter tail rotor blade from composite

laminated materials

4.1Design and Fabrication

A development of a tail rotor blade is performed in four phases:

(a) The blades design on the working station using designing system


2860

(b) Preparation and cutting of blade components on the cutting system

(c) Blade manufacturing in a two-section metal die

(d) Final verification testing.

In the blade manufacturing procedure, the conventional composite materials with

epoxy resin matrix, a fiberglass filament spar, an eighteen-section skin of laminated fabrics,

some carbon filament embedded along the trailing edge, a core, leading edge protection strips

of polyurethane and stainless steel etc. were used. All the used materials are standard

products

Fig. 4.1.1 Automated composite garment cutting facility.

The trailing edge contour of the airfoil is formed by a continuous structural pocket

which has a polyurethane foam core and a fiberglass skin. The upper and lower skins are

fabricated from woven fiberglass that is laid up with the fibers oriented at ±45° and 0°/90° to

the blade longitudinal axis. On the blades, the in plane blade natural frequency is tuned by

stiffening the trailing edge of lower skin with some carbon filaments In assembly, the first

process is to cut the fiberglass fabrics to the require shape and stacking it to build up the

required shapes

Next stage is woven wrap and placed it in a matched metal tool, together with the

fiberglass filament spar, uncured trailing edge skins, polyurethane foam core and tool

transferred to heated pattern press.


2861

Fig.4.1.2 Matched aluminium die.

The TRB consists of spar, tail section, Anti Icing System,Blade Root, Blade Tipare

the main structure components.

Some of the salient specifications of Tail Rotor Blades (TRB) are –

(a) Blade Length - 1719 mm

(b) Blade weight (single) - 10 KG Appx.

(c) Flex beam weight- 2.7KG Appx.

Fig. 4.1.3 Cross sectional view of a tail rotar blade

4.2 Testing

The verification test program for the helicopter blade encompassed static and dynamic

testing. The static tests of the tail blade involved experimental evaluation of Torsional and

flexional blade stiffness and its elastic axis position.

Dynamic tests involved testing of vibratory characteristics and verification testing of

blade fatigue properties. The purpose of the static tests was to evaluate experimentally

Torsional and flexional stiffness and elastic axis position of the blades. To fit the blade


2862

model, a robust

Facility frame made of steel L and U-profiles was employed. For load application, i.e.

for force and torque, an airfoil clamp and system of wheels and cables mounted on a special

frame made of steel profiles were used. For displacement measurement, comparators with an

accuracy of 0.01 mm were used.

Fig.4.1.4 Load-introduction airfoil clamp in static testing.

5. EXPERIMENTAL RESULTS

With the help of different experimental techniques we found the results which are tabulated

below.

Table 5.1. Resin content in the flex beam

AREA

WT

RESIN

CONTENT

VOLATILE

CONTENT

DSC

TEST

(Ts)

DSC

TEST

(Tp)

ILSS

TEST

402.14

g/m2 31.99% 0.65% 139.68 151.87

99.15

&

1451.87

N/mm2

434.58

g/m2 31.39% 0.29% 139.95 151.31

93.65

&

1390.69

N/mm2

418.56

g/m2 34.15% 0.34% 143.14 153.78

90.28

&

1292.57

N/MM2


2863

Table 5.2. Stiffness vale of each flex beam

Sl.

No.

Mean

Hub

Thickness

Stiffness

Value in

Kg/Mm WT. in kg

1 13.4925 0.67 2.69

2 13.481 0.67 2.698

3 13.495 0.71 2.758

4 13.482 0.67 2.696

5 13.487 0.66 2.694

6 13.494 0.67 2.692

7 13.487 0.68 2.693

8 13.4855 0.67 2.696

9 13.4875 0.66 2.679

10 13.476 0.66 2.69

11 13.4915 0.67 2.701

12 13.488 0.67 2.693

13 13.4885 0.67 2.7

14 13.483 0.67 2.702

15 13.494 0.67 2.701

16 13.4825 0.68 2.746

17 13.489 0.68 2.695

18 13.487 0.67 2.701

19 13.486 0.67 2.698

20 13.489 0.68 2.7

21 13.488 0.7 2.71

22 13.486 0.7 2.696

23 13.4875 0.7 2.708

24 13.486 0.67 2.693

25 13.4 0.68 2.692

26 13.4845 0.68 2.696

27 13.493 0.68 2.69

28 13.487 0.68 2.704

29 13.4855 0.68 2.701

30 13.4445 0.73 2.691

31 13.498 0.67 2.698


2864

32 13.481 0.68 2.69

33 13.487 0.7 2.7

34 13.4625 0.66 2.698

35 13.4695 0.68 2.699

36 13.489 0.68 2.704

37 13.488 0.67 2.712

38 13.4765 0.67 2.712

39 13.476 0.68 2.685

40 13.483 0.67 2.69

41 13.4805 0.68 2.7

42 13.4825 0.68 2.7

43 13.4955 0.68 2.7

44 13.495 0.68 2.705

45 13.4685 0.68 2.697

46 13.478 0.67 2.704

47 13.487 0.66 2.708

48 13.461 0.68 2.701

49 13.4935 0.682 2.702

50 13.4945 0.68 2.701

51 13.466 0.66 2.682

52 13.478 0.66 2.682

53 13.469 0.66 2.68

54 13.4765 0.67 2.68

55 13.476 0.66 2.692

56 13.4745 0.64 2.701

57 13.48 0.68 2.683

58 13.486 0.66 2.686

59 13.478 0.67 2.684

60 13.475 0.65 2.68

Table 5.3 show the data of Bests of best and worst of worst

Sl

No

ARM

THICKNESS

HUB

THICKNESS

WT

IN

KG

1 8.778 8.811 13.498 2.698


2865

2 8.777 8.814 13.48/13.491 2.701

3 8.874 8.814 13.483/13.491 2.704

4 8.832 8.84 13.474/13.491 2.7

5 8.81 8.842 13.475/13.486 2.69

6 8.98 8.989 13.474/13.478 2.712

7 8.705 8.715 13.479/13.487 2.685

8 8.994 8.892 13.484/13.494 2.704

9 8.769 8.812 13.492/13.497 2.701

10 8.832 8.864 13.490/13.497 2.702

11 8.934 8.856 13.456/13.466 2.701

12 8.894 8.872 13.480/13.492 2.698

13 8.848 8.866 13.482/13.492 2.701

14 8.824 8.884 13.486/13.492 2.695

15 8.964 8.832 13.479/13.486 2.746

16 8.843 8.812 13.491/13.497 2.701

17 8.915 8.924 13.480/13.486 2.702

18 8.812 8.82 13.484/13.493 2.7

19 8.842 8.864 13.496/13.493 2.692

20 8.864 8.873 13.478/13.486 2.696

Table 5.4 experimental final results

6. Conclusions

This work has been undertaken, with an objective to explore the stiffness of the flex

beam and hence achieve six sigma through shanin methodology and to study the mechanical

properties of the composite materials used in manufacturing of the flex beam. The present

Expt.

No. Pre.

Cooling

rate

2nd

heating

rate

Precom

paction

temp

1st dwell Resin

content

1 660 1.6 1.1 78 38 Low

2 660 1.6 1.1 80 44 High

3 660 2 1.3 78 38 High

4 660 2 1.3 80 44 Low

5 664 1.6 1.3 78 44 Low

6 664 1.6 1.3 80 38 High

7 664 2 1.1 78 44 High

8 664 2 1.1 80 38 Low


2866

work reports the use of failure of flex beam due to high stiffness. This work focused at

providing knowledge to enhance further research in improving the mechanical properties of

the flex beam and improving the stiffness of the flex beam by undergoing certain procedures.

However, more work is needed to demonstrate the full potential of these techniques. The

present study does not include the possibly major effect of failure of flex beam. This can be

another strong contributor to the unsteady loading fluctuation on a tail rotor blade.

SCOPE OF FUTURE WORK

The present scope in research and development field is to produce flex beams under

the required stiffness criteria. This work provides for exploration in finding out the main

cause of over stiffness of flex beam and finding the problem through root cause analysis

using shanin methodology. Researchers can consider other aspects such as using of fish-bone

diagram, 7 quality control technique, six sigma methodology etc. Also varying the input data

that can contribute to good amount of work in future. One of the other important aspects

would be to develop composites using different grades and making use of new techniques

REFERENCES

1. Guyett, R.P. and Cardrick, A.W., The Certification of Composite Airframe Structures,

Symposium on large scale composite structures, Aeronautical Journal, The Royal

Aeronautical Society, London, July 1980, 84.

2. Rasuo, B., Full-Scale Fatigue Testing of Helicopter Blades from Composite Laminated

Materials, ECCM-9, 4-7 June 2000, Brighton, UK

3. Adams, D. O. and Kearney, H. L., Full-Scale Fatigue Testing of Advanced Fiber

Composite Components, Journal of the American Helicopter Society, Vol. 31, April 1986

4. Rasuo, B., Aircraft Production Technology, Faculty of Mechanical Engineering, University

of Belgrade, Belgrade, 1995

5. Lemanski, S. L. Weaver, P. M. and Hill, G. F. J., Design of Composite Helicopter Rotor

Blades to Meet Given Gross- Sectional Properties, Aeronautical Journal, the Royal

Aeronautical Society, London, Oct. 2005.

6.P.Priyanka,Deivanai Kathiresan,” A Machine Learning Approach To Mainframe Analysis”,

International Journal Of Innovations In Scientific And Engineeringresearch,Vol.4,Issue.1,18-

24,2017.


2867

2868

Documents

ACHIEVING DESIRED STIFFNESS OF FLEX BEAM USING SHAININ … · 2018-09-01 · ACHIEVING DESIRED STIFFNESS OF FLEX BEAM USING SHAININ METHODOLOGY 1 Shashikumar C B, 2 Amaresh Kumar