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ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED SCIENCES

M.Sc. THESIS

Murat ÖNŞEN

THE USE OF COMPOSITE MATERIALS IN AUTOMOTIVE INDUSTRY

DEPARTMENT OF MECHANICAL ENGINEERING

ADANA, 2010

ÇUKUROVA ÜNİVERSİTESİ

FEN BİLİMLERİ ENSTİTÜSÜ


Murat ÖNŞEN

A THESIS FOR DEGREE OF MASTER OF SCIENCE DEPARTMENT OF MECHANICAL ENGINEERING

We certified that the thesis titled above was reviewed and approved for the award degree of the master of mechanical engineering by the board of jury on 31/05/2010. ……………………………………… ……………………………. …………………………. Prof. Dr. Melih BAYRAMOĞLU Prof. Dr. Necdet GEREN Doç. Dr. Nihat ÇELİK Supervisor Member Member This PhD Thesis is performed in Department of Mechanical Engineering of the Institute of Natural and Applied Sciences of Çukurova University. Registration No:

Prof. Dr. İlhami YEĞİNGİL Director

Institute of Natural and Applied Sciences Note: The use of tables, figures and photographs (original or referenced) from this thesis, without proper

reference, is subject to provisions of Law 5846 concerning Intellectual Property and Artistic Creations.

I

ABSTRACT

M.Sc. THESIS


MURAT ÖNŞEN

UNIVERSITY OF ÇUKUROVA

INSTITUTE OF NATURAL AND APPLIED SCIENCES DEPARTMENT OF MECHANICAL ENGINEERING

Supervisor: Prof.Dr. Melih BAYRAMOĞLU

Year: 2010, Pages: 131 Jury : Prof. Dr. Melih BAYRAMOĞLU Prof. Dr. Necdet GEREN Assoc. Prof. Dr. Nihat ÇELİK

The automotive industry's use of structural composite materials began in the 1950s. Since those early days, it has been demonstrated that composites are lightweight, fatigue resistant and easily moulded to shape in other words, a seemingly attractive alternative to metals. However, there has been no widespread switch from metals to composites in the automotive sector. This is because there are a number of technical issues relating to the use of composite materials that still need to be resolved including accurate material characterization, manufacturing and joining. This paper reports composite materials determining by Ashby’s material selection technique usage in automotive industry. Especially bus exterior and interior components manufacturing by fiber reinforced polymers (FRP) are used in this master thesis.

Keywords: Material selection, composite materials, bus components, Ashby’s

technique, Fiber reinforced polymers

II

ÖZ

YÜKSEK LİSANS TEZİ

OTOMOTİV SANAYİNDE KOMPOZİT MALZEMELERİN KULLANIMI

Murat ÖNŞEN

ÇUKUROVA ÜNİVERSİTESİ FEN BİLİMLERİ ENSTİTÜSÜ

MAKİNE MÜHENDİSLİĞİ ANABİLİM DALI

Danışman: Prof. Dr. Melih BAYRAMOĞLU Yıl: 2010, Sayfa: 131 Jüri : Prof. Dr. Melih BAYRAMOĞLU

Prof. Dr. Necdet GEREN Doç. Dr. Nihat ÇELİK

Otomotiv sanayinde kompozit malzeme kullanımı 1950’li yıllarda başladı. İlk

uygulamalarından itibaren kompozit malzemeler hafif, malzeme yorulmasına karşı dayanıklı ve kolaylıkla şekillendirilebilen, metallerin yerine kullanılabilecek alternatif malzeme olduğu ispatlanmıştır. Birçok özelliğinin iyi bilinmesine rağmen metallerden, kompozit malzeme kullanıma geçiş, malzeme karakteristiğindeki belirsizliklerden, üretim ve malzemelerin birleşimi gibi konulardaki belirsizliklerden dolayı tam anlamıyla yapılamamıştır. Bu projede, Ashby malzeme seçim tekniğiyle belirlenen kompozit malzemelerin otomotiv sanayinde kullanımı üzerine birçok örneklendirme yapılarak, kompozit malzemelerin iyi birer alternatif olduğu gösterilmiştir. Özellikle otobüs dış ve iç giydirme malzemelerinde elyaf destekli plastik malzemeler tez içeriğinde kullanılmıştır. Anahtar Kelimeler: Malzeme seçimi, kompozit malzemeler, otobüs parçaları,

Ashby tekniği, Elyaf destekli plastikler

III

ACKNOWLEDGEMENTS

I express sincere appreciation to Prof. Dr. Melih Bayramoğlu for his

guidance and encouragement throughout the research. The thesis could be much

disorganized, without his analytical thoughts and experience in summing up

conclusions.

I wish to express my special thanks to Mr. İhsan Otabatmaz from TAI

(Turkish Aerospace Industries) for introducing me by composite material world.

I am thankful to my colleague, Mr. Çetin Doğukaya for his helpful critics

and also for providing deeply composite information in his experience.

I want to express my special thanks to my manager, Mr. İbrahim Eserce

from Temsa Global, for his great support and valuable contribution.

Finally, I would like to express my deep gratitude to my family; my mom,

dad, sisters who have always supported and confided in me in with endless trust

through my education. Great thanks.

IV

CONTENT PAGE

ABSTRACT…………………………………………………….………………….....I

ÖZ………………………………………………………………………………….....II

AKNOWLEDGEMENTS…………………………………………………………...III

CONTENT……………………………………………………………….………….IV

LIST OF TABLES……………………………………………….………………...VII

LIST OF FIGURES……………………………………………………………….VIII

1. INTRODUCTION………………………………………………………………..1

2. PREVIOUS STUDIES……………………………………………………………5

2.1. Composite Materials………………………………………………………...5

2.2. Manufacturing Processes of Composite Materials………………………….7

2.2.1. Wet Lay-up/Hand Lay-up…………………………………………….7

2.2.2. Resin Transfer Molding Process (RTM)……………………………...8

2.2.3. Sheet Molding Compound (SMC)……………………………………9

2.2.4. Rotational molding…………………………………………………..10

2.2.5. Infusion Process……………………………………………………..12

2.3. Advantages of Composite Materials……………………………………….13

2.4. Design of Composite Components (Fiber Orientation)……………………15

2.5. Mechanical Properties of Composite Materials……………………………16

2.5.1. Energy Absorption in Various Composite Materials………………..16

2.5.2. Fatigue Resistance…………………………………………………..18

2.5.3. Impact Damage Response in Composite Materials…………………18

2.6. Cost Structure of Composites……………………………………………...19

2.7. Material Selection Methods………………………………………………..21

2.7.1. Ashby’s Method……………………………………………………..21

2.7.2. Dargie’s Method…………………………………………………….21

2.7.3. Decision Matrices…………………………………………………...22

2.7.3.1. The Pugh Method…………………………………………..22

2.7.3.2. The Weighted-Properties Method…..……………………...23

2.7.3.3. The Pahl & Beitz Decision Matrix…………………………23

V

2.8. Material Selection……………………………………………………….....23

2.8.1. Material Selections for Exterior Trimming Parts…………………....26

2.8.1.1. Bumper……………………………………………………..26

2.8.1.2. Fender………………………………………………………29

2.8.1.3. Bus Roof Access Door…………………………………......30

2.8.2. Material Selections for Interior Trimming Parts……………………31

2.8.2.1. Sandwich Floor…………..………………………………...31

2.8.2.2. Pedal Box……………………………………………..……32

3. MATERIAL AND METHOD…………………………………………………..33

3.1. Materials…………………………………………………………………...33

3.1.1. Reinforcements……………………………………………………...33

3.1.1.1. E Glass Fiber……………………………………………….33

3.1.1.2. Fabric Types and Constructions…………………………....33

3.1.1.3. Fiber Orientation…………………………………………...35

3.1.2. Bulk Materials………………………………………………………35

3.1.2.1. Unsaturated Polyester Resin……………………………….35

3.1.3. Thermoplastic Materials…………………………………………….36

3.1.3.1. Acrylonitrile Butadiene Styrene (ABS)……………………36

3.2. Method……………………………………………………………………..37

3.2.1. Composites Based Automotive Components………………………..37

3.2.2. Manufacturing Process Selection Criteria…………………………..39

3.2.3. Design for Excellence (DFX)……………………………………….40

3.2.4. Design for Manufacturing and Assembly (DFMA)…………………41

3.2.5. Test Methods for Composite Materials………...................................43

3.2.5.1. Tension Test………………………………………………..44

3.2.5.2. Three-Point Bending Test………………………………….46

3.2.5.3. Heat Deflection Test……………………………………….47

3.2.5.4. Barcol Test…………………………………………………48

3.2.5.5. Burn off Test……………………………………………….49

3.2.5.6. Burning Behaviour Test……………………………………50

3.2.5.7. Melting Test………………………………………………..51

VI

3.2.5.8. UV Resistance Test………………………………………...52

3.2.5.9. Heat Cycle Test…………………………………………….54

3.2.5.10. Thermal Shock Test………………………………………..55

3.2.5.11. Heat Aging Test……………………………………………55

3.2.5.12. Chemical Resistance Test………………………………….56

3.2.5.13. Abrasion Resistance Test………..…………………………56

3.2.5.14. Drop Impact Test…………………………………………..58

3.2.5.15. Vicat Softening Test……………………………………….58

3.2.6. Ashby Method and Material Selection Software CES………………59

3.2.7. Material Index for Exterior and Interior Trimming Parts…………...63

4. RESULTS AND DISCUSSIONS……………………………………………….65

4.1. Material Selection……………………………..…………………………...65

4.1.1. Material and Process Selection for Exterior Trimming Parts………65

4.1.1.1. CES Selector on Limit Stage for Exterior Trimming Parts...66

4.1.1.2. CES Selector on Graph Stage for Exterior Trimming Parts.70

4.1.1.3. Test Results for Exterior Trimming Parts………………….80

4.1.2. Material and Process Selection for Interior Trimming Parts………..84

4.1.2.1. CES Selector on Limit Stage for Interior Trimming Parts…85

4.1.2.2. CES Selector on Graph Stage for Interior Trimming Parts...92

4.1.2.3. Test Results for Interior Trimming Parts…...……………...97

5. CONCLUSIONS……………………………………………………………….103

REFERENCES………………………………………………………………...107

CURRICULUM VITAE……………………………………………………….113

APPENDIX...…………………………………………………………………..114

VII

LIST OF TABLES PAGE

Table 3.1. Mechanical properties of E glass fibers used……………………............33

Table 3.2. Technical properties of Polipol 344-TA and 336 used in closed

and open mold applications…...………….……………..........................36

Table 3.3. ABS sheet material properties according to test results performed……..36

Table 3.4. Wear Resistance Test conditions………………………………………..57

Table 3.5. Evaluated conditions for wear resistance test…………………………...57

Table 4.1. Defined design requirements for bumper and fender................................65

Table 4.2. Properties of alternative materials for bumper and fender………………66

Table 4.3. Mechanical properties used in limit stage for exterior parts……………..67

Table 4.4. Cost and weight values calculated for bumper by Catia…………………73

Table 4.5. Cost and weight values calculated for fender by Catia…………………..73

Table 4.6. Three-point bending test results and average values for hand lay-up

and RTM………………………………………………………………….80

Table 4.7. HDT test results and average values for the samples produced by

hand lay-up and RTM processes ………………………………………...82

Table 4.8.Tension test results for hand lay-up and RTM samples…………………..83

Table 4.9. Burn off results for hand lay-up and RTM samples……………………..83

Table 4.10. Design requirements of Headlining…………………………………….85

Table 4.11. Properties of alternative materials for Headlining……………………...85

Table 4.12. Mechanical properties used in limit stage for interior parts……………86

Table 4.13. The weight and cost values for headlining with alternative materials….97

Table 4.14. Test results for interior trimming material (ABS) ……………………101

VIII

LIST OF FIGURES PAGE

Figure 2.1. Hand lay-up process………………………………………………….......8

Figure 2.2. RTM process…………………………….……………………………….9

Figure 2.3. SMC process…………………………………………………………….10

Figure 2.4. Rotational molding's four basic stations………………………………...11

Figure 2.5. Infusion Process………………………………………………………....13

Figure 2.6. Fibre orientation- anisotropy…………………………………................16

Figure 2.7. Specific energy absorption of different materials………………………17

Figure 3.1. Bumper with exterior and interior appearance …………………………38

Figure 3.2. Fender on the vehicle and backside …………………………………….38

Figure 3.3. Shimadzu Autography test device...…………………………………….45

Figure 3.4. Dimension of tensile test specimen used in experiment………………...46

Figure 3.5. Shimadzu Autography test apparatus for three-point bending test……...47

Figure 3.6. a. HDT test device, b. Quadrant Engineering Plastic Products test

geometry………………………………………………………………...48

Figure 3.7. Barcol Test device……………………………………………………….49

Figure 3.8. Burn off test oven ……………………………………………………….50

Figure 3.9. The shape and dimensions of the burning behaviour test specimen used in

experiment……………………………………………………………….51

Figure 3.10. Xenon test device used in weathering test……………………………..54

Figure 3.11. Heat cycle test application sketch……………………………………...55

Figure 3.12. Abrasion test device used for interior trimming parts…………………57

Figure 3.13. Apparatus with a direct-contact heating unit…………………………..59

Figure 3.14. Relationship among design requirements, material, and process needs 61

Figure 3.15. Relationship between design flow chart and material…………………61

Figure 3.16. Ashby’s material selection strategy in four steps……………………...62

Figure 3.17. Stiff beam length L and minimum mass………………………………63

Figure 4.1. Alternative materials found after entering minimum and maximum

density and cost values in limit stage of CES………………………...68

IX

Figure 4.2. Alternative materials obtained after entering minimum and maximum

requirements for mechanical properties…………………………………68

Figure 4.3. Thermal and electrical properties of candidate materials……………….69

Figure 4.4. Optical, Processability, Durability values of the candidates……………69

Figure 4.5. Durability values of the candidate materials……………………………70

Figure 4.6. Density vs. Young’ modulus for exterior trimming parts………………71

Figure 4.7.Working area on young’ modulus vs. density graph stage………………71

Figure 4.8. Alternative materials on young’ modulus vs. density graph stage……...72

Figure 4.9. Bumpers’ 3D models drawn by Catia…………………………………..73

Figure 4.10. Bumpers’ 2D drawings drawn by Catia……………………………….74

Figure 4.11. Fender’s 3D drawing drawn by Catia…………………………………74

Figure 4.12. Pre-processes are shown on mass range vs. material class……………76

Figure 4.13. Alternative processes on section thickness vs. shape class……………77

Figure 4.14. Pre-processes on Section thickness vs. shape class……………………78

Figure 4.15. Roughness values of alternative manufacturing methods……………..79

Figure 4.16. Pre-selected manufacturing methods by roughness…………………...79

Figure 4.17. Stress-strain curves plotted by means of hand lay up specimen for three-

point bending test………………………………………………………80

Figure 4.18. Stress-strain curves plotted by means of RTM specimens for three-point

bending test…………………………………………………………….81

Figure 4.19. Limit stage for headlining after entered density and cost……………...86

Figure 4.20. Composition and Mechanical properties of Headlining……………….88

Figure 4.21. Thermal and optical material properties for headlining……………….88

Figure 4.22. Durability results for headlining material selection…………………...89

Figure 4.23. Durability results for candidate materials……………………………..89

Figure 4.24. Physical attributes shown on limit stage………………………………90

Figure 4.25. Economic attributes for headlining process selection…………………91

Figure 4.26. The values of cost modelling, process characteristic and shape factor..91

Figure 4.27. Alternative materials on density vs. young’ modulus for headlining…93

Figure 4.28. Exact area for alternative headlining materials on young’s modulus vs.

density………………………………………………………………….93

X

Figure 4.29. Alternative materials for interior trimming……………………………95

Figure 4.30. Alternative materials for headlining on shape factor vs. elongation…..96

Figure 4.31. Pre-selected materials on shape factor vs. elongation…………………96

Figure 4.32. Headlining’3D drawings as front and rear drawn by Catia……………97

1.INTRODUCTION Murat ÖNŞEN

1

1. INTRODUCTION

The requirement for energy saving in the automotive industry has risen

dramatically over the years. One of the options to reduce energy consumption is

weight reduction. However, the designer should be aware that in order to reduce the

weight, the safety of the car passenger must not be sacrificed. A new invention in

technology material was introduced with polymeric based composite materials,

which offer high specific stiffness, low weight, corrosion free, and ability to produce

complex shapes, high specific strength, and high impact energy absorption.

Substitution of polymeric based composite material in automotive components was

successfully implemented for fuel and weight reduction. (Suddin, Salit, Ismail,

Maleque, Zainuddin, 2004)

In its most basic form a composite material is one which is composed of at

least two elements working together to produce material properties that are different

to the properties of those elements on their own. In practice, most composites consist

of a bulk material (the ‘matrix’), and a reinforcement of some kind, added primarily

to increase the strength and stiffness of the matrix. This reinforcement is usually in

fibre form.

Fiber reinforced composite materials have been widely used in various

transportation vehicle structures because of their high specific strength, modulus and

high damping capability. If composite materials are applied to vehicles, it is expected

that not only the weight of the vehicle is decreased but also that noise and vibration

are reduced. In addition to that, composites have a very high resistance to fatigue and

corrosion (Shin, Lee, 2002)

Composite production techniques utilize various types of composite raw

materials, including fibers, resins, mats, fabrics, and molding compounds, for the

fabrication of composite parts. Each manufacturing technique requires different types

of material systems, different processing conditions, and different tools for part

fabrication. Each technique has its own advantages and disadvantages in terms of

processing, part size, part shapes, part cost, etc. Composite part production success


2

relies on the correct selection of a manufacturing technique as well as judicious

selection of processing parameters (Mazumdar, 2002).

Material selection in the automobile industry is an artful balance among

market, societal, and corporate demands, and is made during a complex and lengthy

product development process. Actual selection of a particular material for a specific

application is primarily driven by the trade-off between the material's cost (purchase

price and processing costs) and its performance attributes (such as strength,

durability, surface finish properties, and flexibility) (Andrea and Brown, 1993)

The selection of the correct materials for a design is a key in the process

because it is the crucial decision that links computer calculations and lines on an

engineering drawing with a working design. Materials, and the manufacturing

processes which convert the material into a useful part, underpin all of engineering

design. The enormity of the decision task in materials selection is given by the fact

that there are well over 100.000 engineering materials to choose from. There is no

method or small number of methods of materials selection that has evolved to a

position of prominence. Partly, this is due to the complexity of the comparisons and

trade-offs that must be made. Often the properties compared cannot be placed on

comparable terms so clear decision can be made. Partly it is due to the fact that little

research and scholarly effort have been devoted to the problem (Farag, 1997)

In this study, material selection is the key issue to evaluate the alternative

materials for automotive industry. Alternative materials for automotive components

have been determined by Ashby’ material and manufacturing selection method that is

called as Cambridge Engineering Selector (CES). CES selector has two important

stages as limit and graph to assist in material and manufacturing method selection.

First of all, in the limit stage, specified material properties obtained from

material universe were used to determine alternative materials and manufacturing

methods. Limit stage inputs were entered to software as arithmetic values while limit

stage outputs were obtained from material and manufacturing list as materials or

manufacturing methods. Secondly, graph stage was used to evaluate and compare

pre-selected materials and manufacturing methods. At the end of the two stages, pre-

selected materials and manufacturing methods were determined by material and


3

manufacturing method properties obtained from material and process universe.

Before the stages, material selections without CES selector have been performed to

define alternative materials and material properties that could be used for exterior

and interior components in automotive industry.

On the other hand, alternative materials for automotive components as

exterior trimming parts; bumper and fender, and as interior trimming part;

headlining, have been selected to carry out required material tests including

mechanical, physical, thermal, burning behaviour and chemical resistance tests. Test

specimens for exterior trimming parts have been obtained from glass fibre reinforced

plastic (GFRP) while test specimens for interior trimming part have been obtained

from ABS thermoplastic materials.

In conclusion, some of comparisons have been performed between materials

selected without the aid of the CES selector and materials determined by CES

selector including limit and graph stages. The best alternative materials and

manufacturing methods were exactly determined by comparisons between limit stage

results and graph stage results. The best alternative materials determined by CES

selector were evaluated according to the results of the tests that have been made for

exterior and interior materials as GFRP and ABS.


4

2.PREVIOUS STUDIES Murat ÖNŞEN

5

2. PREVIOUS STUDIES

2.1. Composite Materials

To fully appreciate the role and application of composite materials to a

structure, an understanding is required of the component materials themselves and of

the ways in which they can be processed. This section looks at basic composite

theory, properties of materials used and then the various processing techniques

commonly found for the conversion of materials into finished structures (Gurit,

2001)

Composite materials are interesting because they have been used for

thousands of years in demanding structural applications, and we can expect them to

be used indefinitely. Historical composites include cellulose-reinforced lignin

(wood), straw reinforced mud (bricks), and steel reinforced concrete. In a general

meaning, composite materials for construction, engineering, and other similar

applications are formed by combining two or more materials in such a way that the

constituents of the composite materials are still distinguishable, and not fully

blended. Composite materials currently refer to materials having strong fibers

surrounded by a weaker matrix material. Today, the most common man-made

composites can be divided into three main groups: Polymer Matrix Composites

(PMC’s), Metal Matrix Composites (MMC’s), Ceramic Matrix Composites (CMC’s)

(Gurit, 2001)

The primary functions of the resin are to transfer stress between the

reinforcing fibers, act as a glue to hold the fibers together, and protect the fibers from

mechanical and environmental damage. Resins are divided into two major groups

known as thermoset and thermoplastic. Thermoset resins are usually liquids or low

melting point solids in their initial form. When used to produce finished goods, these

thermosetting resins are “cured” by the use of a catalyst, heat or a combination of the

two. Once cured, solid thermoset resins cannot be converted back to their original

liquid form. Unlike thermoplastic resins, cured thermosets will not melt and flow but

will soften when heated (and lose hardness) and once formed they cannot be


6

reshaped. The most common thermosetting resins used in the composites industry are

unsaturated polyesters, epoxies, vinyl esters and phenolics. In addition, among the

thermoplastic resins the most often used include polyethylene, polystyrene,

polypropylene, acryonitride-butadiene styrene(ABS), acetel, polycarbonate(PC),

polyvinyl chloride(PVC), polysulfone(PSF), polyphenylene sulphide (PPS) and

nylon(semi-crystalline polymide). Resin systems such as epoxies and polyesters have

limited use for the manufacture of structures on their own, since their mechanical

properties are not very high when compared to, for example, most metals. However,

they have desirable properties, most notably their ability to be easily formed into

complex shapes. It is when the resin systems are combined with reinforcing fibres

such as glass, carbon and aramid, those exceptional properties can be obtained. The

resin matrix spreads the load applied to the composite between each of the individual

fibres and also protects the fibres from damage caused by abrasion and impact. High

strengths and stiffnesses, ease of moulding complex shapes, high environmental

resistance all coupled with low densities, make the resultant composite superior to

metals for many applications (American Composite Manufacturing Association,

2004)

Reinforcements are important constituents of a composite material and give

all the necessary stiffness and strength to the composite. These are thin rod like

structures. Fibers consist of thousands of filaments, each filament having a diameter

of between 5 and 15 micrometers, allowing them to be producible using textile

machines. Fibers for composite materials can come in many forms, from continuous

fibers to discontinuous fibers, long fibers to short fibers, organic fibers to inorganic

fibers. The most widely used fiber materials in fiber-reinforced plastics (FRP) are

glass, carbon, aramid, and boron. In polymeric composite terms, a fabric is defined

as a manufactured assembly of long fibres of carbon, aramid or glass, or a

combination of these, to produce a flat sheet of one or more layers of fibres. These

layers are held together either by mechanical interlocking of the fibres themselves or

with a secondary material to bind these fibres together and hold them in place, giving

the assembly sufficient integrity to be handled. Some of them are Unidirectional,


7

O/90, Multiaxial, and other fabrics such as chop strand mat, tissue, braids and so on

(Camelyaf, 2009)

2.2. Manufacturing Processes of Composite Materials

Taking composite materials as a whole, there are many different material

options to choose from in the areas of resins, fibres and cores, all with their own

unique set of properties such as strength, stiffness, toughness, heat resistance, cost,

production rate etc. However, the end properties of a composite part produced from

these different materials is not only a function of the individual properties of the

resin matrix and fibre (and in sandwich structures, the core as well), but is also a

function of the way in which the materials themselves are designed into the part and

also the way in which they are processed (Cripps, 2001)

This section compares a few of the commonly used composite production

methods and presents some of the factors to be borne in mind with each different

process, including the influence of each process on materials selection.

2.2.1. Wet Lay-up/Hand Lay-up

Resins are impregnated by hand into fibres which are in the form of woven,

knitted, stitched or bonded fabrics. This is usually accomplished by rollers or

brushes, with an increasing use of nip-roller type impregnators for forcing resin into

the fabrics by means of rotating rollers and a bath of resin as shown in Figure 2.1.

Laminates are left to cure under Standard atmospheric conditions. Because of its

process simplicity and little capital investment, this process is widely used for

making prototype parts. Test coupons for performing various tests for the evaluation

of reinforcements as well as resins are made using this process. Simple to complex

shapes can be made using this process (Anderson and Colton, 1989)

Woven fabrics of glass, Kevlar, and carbon fibers are used as reinforcing

material, with E-glass predominating in the commercial sector. Epoxy, polyester, and

vinylester resins are used during the wet lay-up process, depending on the


8

requirements of the part. The mold design for the wet lay-up process is very simple

as compared to other manufacturing processes because the process requires mostly a

room temperature cure environment with low pressures. Steel, wood, GRP, and other

materials are used as mold materials for prototyping purposes (Gurit, 2001)

Figure 2.1. Hand lay-up process (Dorsett, 2004)

2.2.2. Resin Transfer Molding Process (RTM)

Fabrics are laid up as a dry stack of materials. These fabrics are sometimes

pre-pressed to the mould shape, and held together by a binder. These preforms are

then more easily laid into the mould tool. A second mould tool is then clamped over

the first, and resin is injected into the cavity. Vacuum can also be applied to the

mould cavity to assist resin in being drawn into the fabrics. This is known as

Vacuum Assisted Resin Injection Moulding (VARIM). Once all the fabric is wet out,

the resin inlets are closed, and the laminate is allowed to cure. Both injection and

cure can take place at either ambient or elevated temperature.

For the RTM process, shown in Figure 2.2, fiber preforms or fabrics are used

as reinforcements. There are several types of preforms such as Glass, carbon, and

Kevlar (e.g., thermoformable mat, conformal mats, and braided preforms) used in the

RTM process. A wide range of resin systems can be used, including polyester,

vinylester, epoxy, phenolic, and methylmethacrylate, combined with pigments and

fillers including alumina trihydrate and calcium carbonates. The mold for the RTM

process is typically made of aluminum and steel but for prototype purposes plastic

and wood are also used (Fisher, 1997).


9

Figure 2.2. RTM process (Cripps, 2001)

2.2.3. Sheet Molding Compound (SMC)

In compression molding operation, the SMC is cut into rectangular sizes and

placed on the bottom half of the preheated mold as shown in Figure 2.3. These

rectangular plies are called charge. The charge usually covers 30 to 90% of the total

area, and the remaining area is filled by forced flow of the charge. The amount of

charge is determined by calculating the final volume or weight of the part. The mold

is closed by bringing the upper half of the mold to a certain velocity. Typically, the

working speed of the mold is 40 mm/s with SMC and 80 mm/s with GMT.

In compression molding, the molds are usually preheated to about 140°C.

With the movement of mold, the charge starts flowing inside the mold and fills the

cavity. The flow of the molding compound causes removal of entrapped air from the

mold as well as from the charge. After a reasonable amount of cure under heat and

pressure, the mold is opened and the part is removed from the mold. The SMC is

obtained by mixing liquid resin, fillers, and fibers into a sheet product. SMC is stored

in rolled form or in a stack of rectangular or square pieces. Compression molding is a

match mold operation in which male and female molds are prepared (SMC

Automotive Alliance of the Society, 1991).


10

Figure 2.3. SMC process (Mazumdar, 2002)

2.2.4. Rotational Molding (RM)

There are basically two different RM processes. These are three steps

rotational molding (RM) and four steps RM processes. Heating and cooling

operations are performed in the same or separate location respectively in three and

four step RM processes. Four step RM process, shown in Figure 2.4, starts with

charging a measured amount of plastic (basically the weight of the solidified molded

product) into a mold that is rotated at relatively low speeds in usually a gas, electric,

or flame fed oven about two axes perpendicular to each other. The oven's heat

penetrates the mold, causing the plastic that is usually in solid form to become tacky

and adhere to the mold female cavity surface. When using solid pellets they are

required to be rather smaller and more uniform than the type used in other processes

such as injection molding or extrusion. With a liquid plastic the heat forms a gel on

the mold surface. Since the mold continues to rotate while the heating continues, the

plastic will gradually become distributed relatively evenly on the mold female cavity

walls through gravitational, mold rotating, force. Gradually the plastic completely

melts forming a homogeneous layer of molten plastic. Following the heating step is


11

cooling the mold. With the mold continuing its rotation, cooling is usually done by

air from a high-velocity fan and/or by a fine water spray over the mold. After cooling

the plastic melt the mold is opened and the solidified product is removed manually or

automatically (Frederick, 2000).

Figure 2.4. Rotational molding's four basic stations (courtesy of The Queen's University,

Belfast)

Nearly all RM products are made from thermoplastics although thermoset

plastics can be used. Linear low-density polyethylene (LLDPE) is the major plastic

used with 85 wt% of all plastics representing different forms of polyethylenes. Other

plastics include nylon, polycarbonate, thermoplastic (TP) polyester, and

polypropylcne. In addition to the usual solid plastic products, these plastics can also

be foamed. While RM has many advantages such as low mold costs, seamless,

stress-free moldings, controlled wall thickness distribution, etc.

2.2.5. Infusion Process

The Vacuum Infusion Process (VIP) is a technique that uses vacuum pressure

to drive resin into a laminate (fiberglass, carbon fiber, and Kevlar). Materials such as


12

fiberglass, carbon fiber, and Kevlar are laid dry into the mold and the vacuum is

applied before resin is introduced. Once a complete vacuum is achieved, resin is

literally sucked into the laminate via carefully placed tubing. This process is aided by

an assortment of supplies and materials (Marquardt, 2006).

Fabrics are laid up as a dry stack of materials as in RTM. The fibre stack is

then covered with peel ply and a knitted type of non-structural fabric. The

completely dry stack is then vacuum bagged, and once bag leaks have been

eliminated, resin is allowed to flow into the laminate. The resin distribution over the

whole laminate is aided by resin flowing easily through the non-structural fabric, and

wetting the fabric out from below. Moldings material generally applies from

aluminum, steel, polymeric materials (Marquardt, 2006).

In infusion process, shown in Figure 2.5, resins are generally epoxy, polyester,

and vinylester while fibres are any conventional fabrics, stitched materials work well

in this process since the gaps allow rapid resin transport. In other words, core

materials are used in it such as PVC, PU based foams any except honeycombs.

Figure 2.5. Infusion Process (Marquardt, 2006)


13

2.3. Advantages of Composite Materials

Composites offer many advantages compared to traditional materials

(American Composite Manufacturing Association, 2009):

Substantial Weight Reduction: FRP composites are typically 30-40%

lighter than steel parts of equal strength. Composite parts can be designed to carry

the same loads as steel. Parts are generally molded at minimum thickness to reduce

weight and minimize molding cycle time. Structure is achieved through proper

section design to add increased strength and stiffness to localized areas as required.

Automotive closure panels are generally two-piece designs consisting of a Class "A"

cosmetic skin backed by a non-appearance structural reinforcement panel.

Lower Manufacturing Complexity: Finished assemblies with fewer parts

cut manufacturing costs and often accelerate design completion and model

introduction. A single composite molding can take the place of up to 15-20

individual steel components and fasteners. With fewer components to procure,

inventory and assemble the net result is tighter tolerances, better fit & finish and

reduced labor cost.

Reduced tooling cost: Tooling for composite parts can be as much as 80%

less than comparable metal parts. Steel parts often require a series of stamping dies to

produce a desired shape in addition to multiple components that must be

subsequently assembled. In most cases, one or two molds and presses take the place

of entire multi-station stamping lines. Bottom line: lower cost, tighter tolerances and

less assembly required.

Unparalleled damage resistance: Composites' dent and ding resistance is

far superior to that of steel, aluminum and thermoplastic panels. Composites do not

dent nor ding. Their coefficient of linear thermal expansion (CLTE) is very similar to

steel that allows them to maintain excellent fit & finish over a wide range of

temperatures. They do not embrittle when exposed to cold temperatures nor will they

melt in the presence of extreme heat as do thermoplastics.

Unrivalled corrosion resistance: FRP composites are superior in corrosion

resistance for any application. Composites do not rust nor corrode when exposed to


14

moisture and road salt and will literally outlast most of the steel components on a

vehicle. Their inherent chemical resistance and dimensional stability make them well

suited for engine components such as valve covers and oil pans.

Better internal damping: Leads directly to reduced noise, vibration, and

harshness (NVH). Fewer parts mean fewer chances for squeaks and rattles.

Composites are inherently better sound insulators than steel.

Improved design flexibility: Unlike metals, composites offer a limitless

"depth-of-draw" range. Stamped metals get thinner as they are drawn to form vertical

walls; whereas, composites offer the ability to maintain a constant cross-sectional

thickness over the entire part. Many shapes that are impossible or economically

prohibitive to form in steel and aluminum can be produced with relative ease in

composites.

Cost-effective solutions: Lower composite investment costs satisfy

automakers' trends toward reduced builds per model. With the current trend towards

niche marketing and frequent design "freshening" production runs of closure panels

are typically shorter. Thus, it is advantageous to minimize both the number and cost

of the tooling as it will be amortized over fewer units.

Comparable aesthetics: Toughened SMC resin provides "first-time-

through" processing comparable to steel. The surface smoothness of most composites

is equal or better than the steel parts surrounding them. Composite panels are

generally assembled onto the vehicle and painted on-line with their steel counter-

parts. Recent advances in formulation chemistry first run capability is now

considered to be equal or better than steel by some original equipment manufacturers

(OEM). On the finished vehicle, composite parts are visually indistinguishable from

steel and aluminum.

2.4. Design of Composite Components (Fiber Orientation)

The development of high-performance fibres opens up completely new

possibilities in the design and structure of components. The targeted application of

reinforcing measures, i.e. orienting the reinforcing fibres along the direction of


15

loading, has made it possible to adapt a component design optimally to the load

conditions with the minimum of material expenditure.

Orienting the fibres, shown in Figure 2.6, in the various directions of loading

serves to adapt the material precisely to the specific requirements placed on it

(loading conditions) that is exactly adaptation that enables the designer to dimension

the component optimally and to achieve the maximum savings in weight. In face of

the anisotropic properties of fibre composites, designers are forced to take a different

approach from that in handling conventional isotropic materials. The targeted

reinforcement of components with fibres gives rise to a series of mechanical

characteristics that differ when measured along different directions in the component.

In the case of fibre composites, the design applies not only to the component itself,

but also to the laminate (Herbert, 2003).

Figure 2.6. Fiber orientation- anisotropy (Herbert, 2003)

2.5. Mechanical Properties of Composite Materials

2.5.1. Energy Absorption in Various Composite Materials

Composites absorb more energy than steel or aluminum. Steel has higher

young’s modulus, yet fails to absorb higher energy absorption. In composites, there

are different kinds of fibers having different stiffness. For instance, carbon fibers are

stronger than glass, yet glass withstand load for a longer time than carbon fibers. The

energy absorption capability of the composite materials, shown in Figure 2.7, offers a


16

unique combination of reduced and improves crashworthiness of the vehicle

structures (Ramakrishna, Hamada, 1998).

Crushing of tube was the method of testing composite specimens and this was

primarily used to determine the energy absorption performance of composite

materials. Energy absorption depends on fiber, matrix, and combinations of them.

Tests conducted by Farely, 1983, showed that on comparable specimens,

carbon fiber reinforced tubes absorb higher energy than those of glass or aramid

fibers. The reasons for this related to the physical properties of fiber, overall failure

mechanisms, and fiber-matrix bond strengths. He concluded that the static crushing

tests were conducted on graphite reinforced composite tubes to study the effects of

fiber and matrix strain failure on energy absorption. To obtain the maximum energy

absorption from a particular fiber could be obtained when the matrix material in the

composite must have a greater strain at failure than the fiber.

Figure 2.7. Specific energy absorption of different materials (Kalyan, 2009)

The specific energy absorption is a linear function of the tensile strength and

tensile modulus of the resin, and that it increases with the order phenolic<

polyester<epoxy for glass fiber tubes. While this observation may be reasonable, it is

not conclusively verified by direct reference to material property data because of the

spread in reported values (Thornton, 1979)


17

The studies carried out by Mamalis, 1997, tend to relate the energy

absorption capability of an FRP to the individual properties of its constituent fibers

and matrix. It was proposed that energy absorption is substantially dependent on the

relative (rather than the absolute) properties of the fibers and matrix. In particularly,

the relative values of fiber and matrix strain significantly affect energy absorption. It

is suggested that the maximum energy absorption from an FRP, a matrix material

with a higher failure strain than the fiber reinforcement should be used to achieve

maximum energy. The orientation of the fibers in a given layer, and the relative

orientation of successive layers within a laminate, can significantly affect a

component’s mechanical properties (Mamalis, Robinson, Carruthers, 1997).

2.5.2. Fatigue Resistance

Generally, composites show excellent fatigue resistance when compared with

most metals. However, since fatigue failure tends to result from the gradual

accumulation of small amounts of damage, the fatigue behaviour of any composite

will be influenced by the toughness of the resin, its resistance to micro cracking, and

the quantity of voids and other defects, which occur during manufacture. As a result,

epoxy based laminates tend to show very good fatigue resistance when compared

with both polyester and vinyl ester, this being one of the main reasons for their use in

aircraft structures (Honnagangalah, 2001)

2.5.3. Impact Damage Response in Composite Materials

A significant amount of research has focused on investigating the damage,

crashworthiness, and behavior of dynamic loading under impact. Impact damage in

composites occurs when a foreign object causes through the thickness and/or in plane

fracture in the material. The damaged areas can be investigated visually or by using

optical or electron microscopy, ultrasonic C-scanning, and acoustic imaging.

Impact damage in composite plates is associated with these major failure

modes: delamination, matrix cracking, and fiber breakage. The matrix cracking and


18

delamination are properties of the resin matrix, whereas the fiber breakage is more

responsive to the fiber specifications and characteristics and is usually caused by

higher energy impacts (Nguyen, Elder, Bayandor, Thomson, Scott, 1999).

Matrix cracking in an impacted composite is caused by tensile stress and

by stress concentrations at the fiber-matrix interface. A higher tensile stress results in

a longer and denser cracking pattern. The total energy absorbed by matrix cracking is

equal to the product of the surface energy and the small area produced by the crack.

Larger crack areas are normally caused by crack branching, in which case the cracks

run in the direction normal to the general direction of fracture. In many cases, the

surface area created by such cracks is much larger than the area parallel to the

primary cracks, increasing the fracture energy significantly. This, in effect, can

increase the toughness of composites or the total energy of damage absorbed during

impact (Honnagangalah, 2001)

Delamination, different orientation of the plies can promote delamination of

two adjacent plies due to the stiffness mismatch at their interface. The delamination

areas are influenced directly by changes in the energy of impact. The cracks, which

can initiate delamination, can propagate through the plies and may be arrested as the

crack tips reach the fiber-matrix interface in the adjacent plies (Nguyen, 1999)

Fiber breakage can be a direct result of crack propagation in the direction

perpendicular to the fibers. If sustained, the fiber breakage will eventually grow to

form a complete separation of the laminate. When reaching the fracture strain limit in

a composite component, it results in fiber breakage. For the same impact energy,

higher capacity of fibers to absorb energy results in less fiber breakage and a higher

residual tensile strength. Secondary matrix damage, which occurs after initial fiber

failure, is also reduced allowing residual compressive strength to increase (Nguyen,

1999)

2.6. Cost Structure of Composites

The cost is the single most major barrier for the limited application of

polymer composites in automobiles today. Most of the cost studies of polymer


19

composites are for body-in-white (BIW) applications because of the significant

weight reduction potential BIWs offer. On a $/lb basis, the cost of polymer

composites is about 2-3 times higher than steel, but a recent study comparing the

composite monocoque designs indicates that the cost of glass-fiber-reinforced

thermosets and carbon-fiber-reinforced thermoplastics are about 62% and 76%

higher than the conventional steel unibody. However, because of the higher weight

reduction potential of, the value of carbon fiber-reinforced composites’ weight

savings lies in the range of 0.78 euro-3.14 euro/kg. Even on a life cycle basis, the

cost of polymer composites is considerably higher than steel unibodies. The major

cost-contributing life cycle stage is manufacturing, which includes material costs. To

be cost competitive on a part-by-part substitution, cycle time and material utilization

must be improved. The material cost plays a key role, particularly at the higher

production volume and for carbon-fiber-reinforced thermoplastic composites. For the

application in structural components where the weight savings potential is less than

for the body-in-white, even larger reduction in the material cost would be necessary.

The need for a shorter cycle time for a typical composite molding process is a

challenging one. Short cycle times achieved by faster cure times may result in

products with a shorter shelf life and lower quality. Shortening cure times may not be

a feasible option, and strategies to determine the most suitable processing method for

a given application are needed. Multiple, parallel production lines could be used to

improve the viability of polymer composite manufacturing processes for the high-

production-volume applications. Although parallel lines may reduce the capital

advantage of polymer composites, a significant reduction in material cost and further

integration and combination of parts in the design will improve composites’ overall

economic viability (Advanced Materials & Composites News, 1999)

This assessment of the current viability of composites in automotive

applications is based on the very limited cost information currently available. The

specific cost estimate provided for a given manufacturing technology should not be

generalized for that technology. Each cost estimate is based on many underlying

assumptions, both technical and economic; the degree of overall cost sensitivity to

these assumptions will vary across different technologies. The use of different


20

sources of information also poses a problem in the consistency of input assumptions

made for the cost estimation. The information drawn from various sources in the

literature and used in this assessment does not allow one-to-one comparison among

various manufacturing technologies for a part application; it does, however, allow

one to assess general, qualitative trends and to identify major barriers to the

economic viability of composite technologies (Sujit, 2001).

2.7. Material Selection Methods

2.7.1. Ashby’s Method

The performance of an engineering component is limited by the properties of

the material of which it is made, and by the shapes to which this material can be

formed. Under some circumstances, a material can be selected satisfactorily by

specifying ranges for individual properties. More often, however, performance

depends on a combination of properties, and then the best material is selected by

maximizing one or more ‘performance indices’. An example is the specific stiffness

E/ρ (E is Young’s modulus and ρ is the density). Performance indices are governed

by the design objectives. Component shape is also an important consideration.

Hollow tubular beams are lighter than solid ones for the same bending stiffness and

I–section beams may be better still. Information about section shape can be included

in the performance index to enable simultaneous selection of material and shape

(Cebon and Ashby, 1992).

2.7.2. Dargie’s Method

The initial screening of materials and processes can be a tedious task if

performed manually from handbooks and supplier catalogs. This difficulty has been

prompted the introduction of several computer-based systems for materials and/or

process selection. As an illustrative example, the system (MAPS 1) was proposed by

Dargie et al.will be briefly described here. For this system, Dargie et al. proposed a


21

part classification code similar to that used in-group technology. The first five digits

of the MAPS 1 code are related to the elimination of unsuitable manufacturing

processes. The first digit is related to the batch size. The second digit characterizes

the bulk and depends on the major dimensions and whether the part is long, flat, or

compact. The third digit characterizes the shape, which is classified on the basis of

being prismatic, axisymmetric, cup shaped, nonaxisymmetric, and nonprismatic. The

fourth digit is related to tolerance and the fifth digit is related to surface roughness

The next three digits of the MAPS 1 code are related to the elimination of unsuitable

materials. The sixth digit is related to service temperature. The seventh digit is

related to the acceptable corrosion rate. The eighth digit characterizes the type of

environment to which the part is exposed.

2.7.3. Decision Matrices

It is necessary that a selected material satisfy more than one performance

requirement. In other words, compromise is need in material selection. We can

separate the requirements into three groups (1) go-no-go parameters, (2)

nondiscriminating parameters, (3) discriminating parameters. Go-no-go parameters

are those requirements, which must meet a certain fixed minimum value. Any merit

in exceeding in fixed value will not make up for a deficiency in another parameter.

Nondiscriminating parameters are requirements that must be met if the material is to

be used at all. Like the previous category these parameters don’t permit Comparasion

or quantitative discrimination. Discriminating parameters are those requirements to

which quantitative values can be assigned. Some of the decision matrices are as

follows:

2.7.3.1. The Pugh Method

It is useful as an initial screening method in the early stages of design. In this

method, a decision matrix is constructed. Each of the properties of a possible

alternative new material is compared with the corresponding property of the


22

currently used material and the result is recorded in the decision matrix as (+) if more

favorable, (-) if less favorable, and (0) if the same. The decision on whether a new

material is better than the currently used material is based on the analysis of the

result of comparison, i.e., the total number of (+), (-), and (0). New materials with

more favorable properties than drawbacks are selected as serious candidates for

substitution and are used to redesign the component and for detailed analysis.

2.7.3.2. The Weighted-Properties Method

The weighted-properties method that includes each material requirement, or

property, is assigned a certain weight, depending on its importance to the

performance of the part in service. A weighted-property value is obtained by

multiplying the numerical value of the property by the weighting factor (α). The

individual weighted-property values of each material are then summed to give a

comparative materials performance index (γ). Materials with the higher performance

index (γ) are considered more suitable for the application.

2.7.3.3. The Pahl & Beitz Decision Matrix

A systematic design approach to concept evaluation developed in Germany

after World War II. It is a method of evaluation based on use-value analysis. The

overall design of the product is broken down into designs for separate functional

modules. Each module can then be considered independently with interactions

between them being kept to a minimum. The major advantage of this approach is the

simplification of the subsequent design process for the individual modules. The

major disadvantage of this method is that by reducing the scope for functional

sharing, an increase in overall complexity of the product often follows. This can

result in manufacturing problems, such as a higher parts count.


23

2.8. Material Selection

Materials selection (MS) is a multidisciplinary activity, which cuts across a

large number of professional expertises. Therefore, it draws together people with

different backgrounds ranging from the essentially technical to the non-technical,

such as marketing for instance (Ferrante, 2000).

Motivations for MS can be either the realization of a completely new product

or, more frequently, the substitution of an existing material. In the latter case, better

performance and cost reduction can be the main driving forces for the process, but

malfunction, weight reduction, feasibility of recycling and processability, are also

frequent motivations. For instance, taking weight reduction, its importance makes of

it one of the main targets for design improvements and MS, particularly in the

automotive industry (Gjosten, 1995)

Generally, any MS event must consider a large number of materials

candidates and premature exclusions have to be avoided. In addition, when facing a

MS problem, engineers are normally asked to choose a solution, which fulfils more

than one objective, that is, not only lower weight, but also low cost, good fatigue

resistance and better fabricability, as well. From these two aspects, four main

principles have to be followed in order to guarantee the success of the MS task.

§ Adoption of the called compromise philosophy, it will deal with the fact that

there is no ideal material and that properties have to be combined and

optimized. For instance, often-high mechanical strength must side with low

fracture toughness.

§ At the early stages of any selection process a macroscopic approach must be

adopted, mainly in order of not to miss any opportunity. Along the way, new

restrictions and additional criteria will be applied to the initial group of

candidates, restricting it further and further until the final choice is made.

§ Interaction of material selection with process selection (PS)

§ Adoption of some method of formalization procedure in order to tackle

multiple objectives


24

The two last mentioned principles are the themes of the present paper and

will be developed using case studies. Some traditional material selection techniques

about polymeric materials and subjects are as follows:

Xinto Cui, Shunxin Wang, S. Jack Hu (2008), reported a new method for

designing lightweight automotive body assemblies using multi-material construction

with low cost penalty. Current constructions of automotive structures were based on

single types of materials, e.g., steel or aluminum. The principle of the multi-material

construction concept was that proper materials were selected for their intended

functions. The design problem was formulated as a multi-objective nonlinear

mathematical programming problem involving both discrete and continuous

variables. The discrete variables in this study were explained the material types and

continuous variables such as the thicknesses of the panels. This problem was then

solved using a multi-objective genetic algorithm. An artificial neural network was

employed to approximate the constraint functions and reduce the number of finite

element runs.

A. Shanion, O. Savadogo (2006) reported replacing and selecting materials

for different engineering applications is relatively common. It must be noted that in

some cases, there is more than a single definite criterion for selecting the right kind

of material. The designers and engineers have to be taken into account a large

number of material selection criteria. Experts usually apply trial and error methods or

build on previous experimentation. In this paper, a new approach has been carried

out for the use of the ELECTRE: ELimination and Choice Expressing the Reality,

model in material selection. By producing a material selection of decision matrix and

criteria sensitivity analysis, ELECTRE has been applied to obtain a more precise

material selection for a particular application, including logical ranking of considered

materials. A list of all possible choices from the best to the worst suitable materials

can be obtained taking into account all the material selection criteria, including the

cost of production. This work shows that ELECTRE can be used successfully in

selecting a suitable material for the particular application of a loaded thermal

conductor.


25

M.M. Farag (1997) presented two quantitative methods of materials

substitution. The first method, performance/cost, is allowed the designer to either

look for a substitute material of similar performance at a lower cost or for a material

with better performance but at a higher cost. The second method, compound

objective function, is allowed the designer to develop different substitution scenarios

based on the relative weights allocated to the different performance requirements.

Using the two, methods to be examined the case of material substitution for interior

motorcar panels are yielded consistent results. Composites of polypropylene

reinforced with 40% hemp or flax fibres rank highest when cost is important, while

wood and cork rank highest when aesthetics and comfort are emphasized. These

results are consistent with the current trends in industry.

2.8.1. Material Selections for Exterior Trimming Parts

2.8.1.1. Bumper

M.N. Suddin, M.S. Salit, N. Ismail, M.A. Maleque, and S. Zainuddin (2004)

have selected polymeric based composite materials because of low weight, high

specific stiffness, high specific strength, high-energy absorption and easy to produce

in complex shapes to produce bumper fascia for Proton Iswara 1.3s Aeroback. The

bumper fascia was made of conventional polyurethane (88% by weight) and

PRIMGLOS (8% by weight) /K46 glass sphere (4% by weight) materials. In this

design, the fascia consists of many curvatures and it is a one-piece moulded part that

is used to manufacture by SMC. In order to strengthen the bumper fascia, the energy

absorber (foam) made of polyurethane was attached on the backside of the fascia.

The rib was designed to support the removable portion of bumper. The rib has a 3

mm thickness, 40 mm width and it follows the shape of the removed portion on the

fascia. Four conceptual designs of a bumper fascia have been developed with a 3-D

solid model that had been carried out using Pro/Engineer software, the weight of the

bumper fascia was obtained through weight analysis of software as well. To decide

the final design of bumper fascia, the matrix evaluation method was used. The


26

evaluation of the bumper fascia conceptual designs was carried out using the

weighted objective method. For each concept, the utility score for each objective was

multiplied with the weight to give relative values. These values were summed up to

get the total values of each concept. The concept with the highest values was

selected. Some parameters are not measurable in simple, quantified ways, but it is

possible to assign utility scores estimated on a points scale. Finally, the relative

utility value of the concepts are calculated and compared. By multiplying each

parameter score by its weighted value, the ‘best’ alternative that has the highest sum

value is chosen as the ‘best’. The fascia was successfully designed with less weight

compared to the current fascia.

S.M. Sapuan, M.A. Maleque, M. Hameedullah, M.N. Suddin, N. Ismail

(2004) have applied a conceptual design approach to the development of polymeric-

based composite automotive bumper system. Various methods of creativity, such as

mind mapping, product design specifications, brainstorming, morphology chart,

analogy and weighted objective methods employed for the development of

composite bumper fascia and for the selection of materials for bumper system. The

evaluation of conceptual design for bumper fascia is carried out using weighted

objective method and highest utility value is appeared to be the best design concept.

Polymer-based composites are the best materials for bumper fascia, which are

aesthetically pleasant, lighter weight and offer many more advantages that are

substantial

R. Hosseinzadeh, Mahmood M. Shokrieh, Larry B. Lessard (2004) have

designed different types of the bumpers for reducing the weight of passenger cars by

using composite structures. Bumpers have three main parts that includes fascia,

beam, and absorber. Bumper beam have designed using different materials such as

aluminum, steel, different types of fibers, thermoplastic and thermoset resins, plastic

engineered products (PEP) etc. and manufacturing methods such as SMC, press for

metal shaping, glass mat thermoplastic (GMT) and was characterized by FEM

modeling in accordance to low velocity impact standards. Conventional materials

(steel and aluminum) showed inappropriate characteristics such as structural failure

and weight increase at the time their specifications were assigned to the model. GMT


27

as the original material of the bumper was studied and the basic shape factors, such

as strengthening ribs, showed their effects in stabilization and rigidity of the

structure. To offer a more suitable material at lower cost and easier production, high

strength SMC composite was proposed to replace GMT and the ribs of the structure

were all removed. The structure showed very good impact behavior compared with

other structures, which all failed and showed manufacturing difficulties due to

strengthening ribs or weight increase due to use of more dense materials. New

surveys based on use of SMC composite materials prove that GMT materials can be

replaced by suitable SMC. The research tries to draw attention to materials whose

manufacturing costs are lower than currently used materials, depicting that 8% of

today cars are made from plastic and composite material. However, the authors

strongly believe more practical tests should be done to verify the stability and

advantages of the proposed structure.

Ping C. Ge, Nancy Wang, Stephen C, Y. Lu (2002) have developed a

preliminary version of an Evolutionary Modeling Approach (EMA), which targeted

at reducing the cost of surrogate model construction process, for the applications that

involve highly nonlinear underlying mapping relationship over a large design space.

Surrogate modeling method was optimized by orthogonal arrays that are used to

simulate system behavior in Taguchi’s parameter and robust design. The EMA

generated surrogate models for an automotive bumper system validated by the (Finite

Element Analysis) FEA and physical test data, demonstrate better prediction

accuracy than the existing simplified simulation while entailed much lower

computational cost compared to FEA. Ford Taurus bumper was a roll-formed beam

and foam system with a ‘‘B’’ beam cross-section. After a list of important design and

performance parameters for a steel bumper system was generated. Design of

Experiments (DOE) was performed a feasible method for an initial data selection in

overall design space, particularly where a large number of design and performance

parameters are involved and their value ranges are relatively bigger. Several

application cases have been conducted in order to study the interplay between

various DOE strategies and aims. They believe that Applications to various

engineering domains beyond automotive bumper system will have been needed for


28

testing and adapting EMA as an integrated part of industrial design decision support

system.

Yan Zhang (2006) has investigated the shallow shell theory, the expression of

dent resistance stiffness of double curvatures shallow shell was obtained under the

concentrated load condition. Lightweight and crashworthiness are two important

aspects of auto-body design. The critical loads resulting in the local trivial dent in the

center of the shallow shell was regarded as the important index for the lightweight of

the automobile parts. The crashworthiness simulation of the lightweight part proved

the validity of the lightweighting process. The bumper of the passenger car was

studied under different materials but remaining its dent resistance. The deformation

history of bumper using new material was achieved after the car crash is re-simulated

with updated part thickness. By simulation, the deformations of bumper made of two

different kinds of material are similar in that plastic hinge and tensional plastic

deformation appear in the middle part of bumper. This rule was applied to the

lightweight design of bumper system by using high strength steel instead of mild

steel. From the difference of the energy absorption between two materials is small,

about 4.1% for beam of the bumper, from which a conclusion can be drawn that it is

feasible to reduce the thickness of the bumper panel based on the dent resistance

evaluation index studied in this research.

M.M. Davoodi (2008) has applied conceptual design approach to the

development of fiber reinforced epoxy composite bumper system. The study

performed by Davoodi describes the use of the composite in energy absorption in car

bumper as a pedestrian energy absorber. The systematic exploitation of proven ideas

or of experience was used to generate the ideas and the most suitable idea was

followed as a guide for conceptual design. The absorber was analyzed

experimentally and the data from these experiments were used to decide on the

number of energy absorber to be used in the design. Final design of the composite

energy absorber in elliptical shape with two slots at both ends was considered. The

method of fixing the energy absorber to the fascia and bumper was also studied. The

work of Neopolen P and American Iron and Steel Institute (AISI) were followed as

guides with some modification in Neopolen P work. In Neopolen P, a series of


29

absorbers was installed in between fascia and beam with the material used was

expanded polypropylene (EPP).

2.8.1.2. Fender

Inês Ribeiro, Paulo Peças, Elsa Henriques, Arlindo Silvo (2008) have aimed

to confirm the importance of analyzing a product in an early stage of its development

on a life cycle perspective in their study. A case study has been developed to outline

this importance, considering the material selection of an automobile front fender. A

set of candidate materials with different characteristics technologically suitable for

an automobile fender were selected to analyze. The selection varied from mild steel

to ultra strength steel and aluminum alloys. Starting from the most basic decision

criterion, the material specific market cost, additional analysis were performed,

including life cycle cost and environmental assessment, verifying that the “best

material” considering different approaches is not always the same. The most

economic material during production stage may not be the most economic one during

the in-use stage and may also not be the most ecological one. Thus, Life Cycle

Assessment (LCA) analysis was performed to compare alternatives on an

environmental basis. Life cycle approaches integrating the companies’ strategies

allow more conscious and informed decisions during product design stages. Finally,

it should be noted that only metals were considered as alternatives. In fact, the

screening of candidate materials, highly dependent on the expertise and experience

of the design team, is a critical issue for any material selection.

2.8.1.3. Bus Roof Access Door

Haibin Ning, Selvum Pillay, Uday K. Vaidya, (2008) have applied a

thermoplastic composite roof access door that replaced an aluminum access door. It

was successfully designed, analyzed, and manufactured using a form-fit-function

approach for a mass transit bus. An innovative combination of thermoplastic

composite materials and processing technology was demonstrated to form the part.


30

The manufactured composite door possesses (a) paintable and aesthetically appealing

surface, (b) enhanced rigidity with 42% reduced free-standing deflection compared

to the aluminum counterpart, and (c) 39% weight saving over the aluminum baseline.

The vibration damping ratio of the thermoplastic composite materials was an order of

magnitude higher compared to the aluminum counterpart. This increase was expected

to reduce vibration and noise emanating from the roof. A 20% deflection difference

was noticed between the results from the FEA model and the prototype (air

conditioning) AC access roof door. It was mainly attributed to the in-plane and out-

of-plane displacements caused by the adhesive layer added between the inner GMT

liner and outer thermoplastic polyolefin (TPO) skin. It was expected that other

bonding methods such as ultrasonic or resistance welding will provide less

deformation. The component demonstration developed for the bus roof access door is

generic to rail cars, trucks, marine, and aerospace structures.

2.8.2. Material Selections for Interior Trimming Parts

2.8.2.1. Sandwich Floor

Natalia S. Ermolaeva, Maria B.G. Castro, Prabhu V. Kandachar (2004) has

developed the system combining structural optimization and materials selection

within the frame of the project, the purpose of which is to provide a knowledge base

for sustainable product design. A sustainable vehicle means not only the lightweight

car, but also an environmentally friendly, affordable vehicle satisfying all current

and/or future legislations on safety, emissions, recyclability, etc. The developed

system was applied for the selection of foams to be used as a core material for

sandwich panels for the upper and lower floor paneling of a concept car. The entire

structure of the bottom part of environmental friendly car was modeled and

optimized for static loads resistance with respect to minimal mass. The requirements

on safety aspects (stiffness, strength, geometrical stability) of the structure were

considered in the formulation of the constraints. The structural optimization resulted

in the bottom structure of minimum weight for each considered combination of


31

materials, providing a concept of lightweight design. The eco-indicator 99 values,

which considered damage to human health, ecosystem quality, and resources, were

calculated and compared for given structure composed of selected materials. The

environmental damage assessment of the structures employing polymeric foams

resulted in very close to each other eco-indicator values and the environmental

performance of these structures can be considered as similar. The best solution, as

resulted from life cycle assessment (LCA), seems to be referred to the lightest

structure, in order to attain the lowest possible fuel consumption. For considered

structural application, it is the use of very low-density phenolic foam as a core

material, followed closely by polymethacrylimide (PMI) foam of low density. The

compound objective function, consisting of the mass, cost, and environmental

indices, was compared for the designs of the considered materials combinations.

They have concluded based on the developed approach and availability of input data,

which the phenolic foam of a very low density, is the best candidate to be used as a

core material in given structure with respect to all considered indices.

2.8.2.2. Pedal Box

S. M. Sapuan (1999) has developed an expert system for material selection

for design of automotive component with fibre reinforced plastic materials. The

expert-system shell KEE (Knowledge Engineering Environment) provides a tool to

store and process expert knowledge. The system concentrates on selecting suitable

materials for automotive components, in particular for major elements of pedal box

system namely the mounting bracket, the accelerator, the clutch and the brake pedals.

Data about the materials and their properties were stored in the frame-based system.

The expert system enables material data to be accessed through user interface.

Selection of the most suitable material was carried out through experience and expert

knowledge (for instance, about manufacturing method for polymeric based

composite materials) written in rule system. Factors like mechanical, physical, and

chemical properties, economic and manufacturing considerations were used in the


32

material selection process. The material must satisfy all the above requirements in

order to become a suitable candidate for a particular component.

3. MATERIAL AND METHOD Murat ÖNŞEN

33

3. MATERIAL AND METHOD 3.1. Materials

3.1.1. Reinforcements

The role of the reinforcement in a composite material is fundamentally one of

increasing the mechanical properties of the neat resin system. All of the different

fibres used in composites have different properties and so affect the properties of the

composite in different ways. The properties and characteristics of common fibres

used in this study are explained in the following sections.

3.1.1.1. E Glass Fiber

E-glass fibers are very popular as composite material reinforcements on

automotive industry because of low cost, high production rates, high strength, high

stiffness, relatively low density, non-flammable, resistant to heat, good chemical

resistance, relatively insensitive to moisture, able to maintain strength properties over

a wide range of conditions, good electrical insulation. E Glass fibre has been chosen

according to DIN 61853. It is available in different forms such as strand, yarns, and

rowing. The fibre reinforcements are produced by Camelyaf was used in this study.

The mechanical properties of the fibre reinforcements are given in Table 3.1. The

same density but different types of fibers such as mat, roving, etc. are used for

exterior components in open molding application to resist the impact loading effect.

Table 3.1. Mechanical properties of E glass fibers used (Camelyaf, 2009) Materials Density (g/cm3) Tensile Strength (MPa) Young modulus

(GPa) E-Glass fiber 2.55 2400 80

3.1.1.2. Fabric Types and Constructions

In polymeric composite terms, a fabric is defined as a manufactured assembly


34

of long fibres of carbon, glass, or a combination of these, to produce a flat sheet of

one or more layers of fibres. These layers are held together either by mechanical

interlocking of the fibres themselves or with a secondary material to bind these fibres

together and hold them in place, giving the assembly sufficient integrity to be

handled. Fabric types are categorized by the orientation of the fibres used, and by the

various construction methods used to hold the fibres together.

0/90° Fabrics; For applications where more than one fibre orientation is

required, a fabric combining 0° and 90° fibre orientations is useful. The majority of

these are woven products. The interlacing of warp (0°) fibres and weft (90°) fibres in

a regular pattern or weave style produces woven fabrics. The fabric’s integrity is

maintained by the mechanical interlocking of the fibres. Drape that is the ability of a

fabric to conform to a complex surface, surface smoothness and stability of a fabric

are controlled primarily by the weave styles such as Plain, Twill, and Satin.

Chopped strand mat (CSM) is a non-woven material, which, as its name

implies, consists of randomly orientated chopped strands of glass, which are held

together – for automotive applications. Today, chopped strand mat is rarely used in

high performance composite components, as it is impossible to produce a laminate

with high fibre content and, by definition, a high strength-to-weight ratio.

Rovings are a loosely associated bundle of untwisted filaments or strands.

Each filament diameter in a roving is the same, and is usually between 13-24μm.

Rovings also have varying weights and the tex range is usually between 300 and

4800.

In this study, chopped strand mat and roving have been used to produce

specimens that simulate exterior trimming parts for open mould applications.

Chopped strand mat was performed at large areas on the component while roving

was applied on corners and sharp edges to resist polymer build up on the part for

open mould applications. 0/90° fabric as plain style, chopped strand mat was

performed to manufacture exterior trimming parts for closed moulding applications.

0/90° fabric, 600 g/m², that produced by Metyx has been laid up as middle layer on

the parts while chopped strand mat, mat8; 450 g/m², that produced by Camelyaf was

applied as bottom and top layers on the part for closed moulding applications.


35

3.1.1.3. Fiber Orientation

Above explanation for different type of fibers as reinforced materials to be

satisfied the last material properties that include mechanical, physical, thermal must

be organized for a successful results.

In this study, two different types of fiber orientations have been applied for

open and closed mold applications. Fiber orientation as 450(mat8-Camelyaf) / 450 /

450 / 450 has been performed for open mould applications while fiber orientation as

450(mat8-Camelyaf) / 450 / 600(0/90°Metyx) / 450 / 450 were used for closed

moulding applications.

3.1.2. Bulk Materials

3.1.2.1. Unsaturated Polyester Resins

Polipol 344-TA is a special formulation thixotropic unsaturated polyester

resin with high reactivity and medium viscosity, designed for hand lay-up and spray

up applications. Because of high heat resistance, it is has been widely used in

automotive industry on motor cabin and hood which have possibility to be exposed

to the heat. The most characteristic properties of Polipol 344-TA polyester resin is its

high HDT and Tg values. In any case, Polipol 344 gives products which will not be

deformed and which have smooth surface and high mechanical properties. Polipol

336 is an orthophtalic based, low viscosity, GRP type unsaturated polyester resin.

Most common usage areas of Polipol 336 are automotive and construction industries.

Polipol 336 is specially made for two side smooth, serial production with RTM and

cold press systems. Resins used in this work and their technical properties are given

in Table 3.2.


36

Table 3.2. Technical properties of Polipol 344-TA and 336 used in closed and open mold applications (Poliya, 2010)

Property Standard Polipol 344-TA Polipol 336

Color ISO 2211 Max. 200 Hazen Max. 100 Hazen

Viscosity at 25°C ISO 2555 800 mPa.s 300 mPa.s

Density at 25°C ISO 1675 1.15 g/cm ³ 1.10 g/cm ³

Flash Point ISO 2719 34°C 28°C

3.1.3. Thermoplastic Materials

3.1.3.1. Acrylonitrile Butadiene Styrene (ABS)

ABS is a three-component polymer made from Acrylonitrile, Butadiene, and

Styrene. ABS is a tough, rigid thermoplastic, resistive to stress cracking and creep

with a high impact strength which is maintained at low temperatures (-40°C). It is

resistive to moisture and chemicals (inorganic salts, alkalis and many acids). It

possesses excellent electrical properties, is heat resistant and flame retardant. When

exposed to the weather there is a reduction in the surface gloss (a graying in color).

These properties make ABS suitable for thermoforming as interior trimming

material. It can be easily processed through machined, bored turned, milled, sawed,

die cut, routed, filed, sanded, ground buffed and polished. ABS may be pigmented

and though they are usually translucent to opaque, they may be produced in

transparent grades. In this study, ABS was used as RAL 7016 color. ABS test panels

were obtained from Hassas Plastik A.Ş and their properties are given in Table 3.3.

Table 3.3. ABS sheet material properties according to test results performed Test Property Standard Unit Value

Tension Young's modulus

ISO 527 N/mm² 1901.5

Stress N/mm² 36.1 Elongation % 2.6

Bending Modulus

ISO178 N/mm² 1881.3

Fracture load N/mm² 56.0


37

3.2. Method

3.2.1. Composite Based Automotive Components

Composite lightweight parts in automotive industry can be classified

according to their applications such as exterior and interior. Exterior components can

be seen when looking at vehicle and directly opened to environmental effects such as

corrosion, crashworthiness. Furthermore, they cover all of the metal construction to

create aesthetic vision on vehicle. For these reasons, exterior parts need to have

necessary mechanical, physical and chemical properties such as high strength against

collisions, high stiffness for energy absorption, lightweight to reduce fuel

consumption, corrosion resistance for increasing life time, non-softening materials to

be used to resist heat and so on. Some of exterior trimming components

manufactured by composite materials are bumper, spoiler, fender, fuel tank, and side

panel.

On the other hand, vehicle interior components design has driven a

significant increase in interior comfort and functionality in recent years, requiring the

use of an increasingly diverse mix of interior plastics and fabrics. Performance

requirements for interior components have increased, with higher operational

temperature requirements, improved emissions/environmental performance needs

and reduced component cost/cycle time in production. Some of the interior

components include front console, headlining or housing and rail covers. Exterior

and interior components investigated in this work are explained in the following

paragraphs.

Bumpers: An automobile bumper fascia is a component, shown in Figure

3.1, which contributes to vehicle crashworthiness during front or rear collisions.

Polymeric materials are applied in the automotive bumper system to satisfy stringent

weight and performance requirements. Bumper system consists of three parts, such

as fascia, energy absorber, and bumper beam. Fascia is an aesthetic cover, which is

usually flexible and non-structural component. Earlier we thought that the safety

bumper of the bus could protect the bus itself. After some laboratory tests and a full-


38

scale frontal collision test, we concluded that the safety bumper could only be

effective at very low speeds (5–7 km/h). Now we know that the goal of developing

and using safety bumpers on buses is to avoid car underrun and to reduce bus

aggressivity against smaller vehicles (Matolcsy, 1997). Aluminum; glass fiber

reinforced plastics, thermoplastic and sometimes steels can be used as a bumper

material.

Figure 3.1. Bumper with exterior and interior appearance

Fenders: It is a vehicle component that uses side of wheels on vehicle as

shown in Figure 3.2 and protects the wheelhouse from direct effects came from

outside. Its material properties play an important role because of impact loading

effects, corrosion risk and visual component on vehicle. Fiber reinforced materials

are generally applied to be produced fenders because of high impact resistance,

toughness, energy absorption resistance, strength and stiffness.

Figure 3.2. Fender on the vehicle and backside

Headlining: Housing panel satisfies the luggage place requirements of driver

and co driver. The part is generally equipped with a lid and divided into two sections.


39

one of the sections is to locate first aid kit, and the personal goods of the driver, the

other section is reserved for the electronic equipment like control units, cabling of

different kinds of control panels such as, destination signs, intercom, A/C unit,

Radio-CD player, etc. As these explanations are seen that headlining is a very

complex and high functionality component in vehicle. For these reasons, material

selection is so important for headlining and other interior trimming parts. Because of

low Investment cost properties, GFRP are alternative material but the best alternative

materials come from thermoplastic materials such as ABS, PU owing to low cost,

lightweight, easily mountable, suitable for attractive complex shapes. The properties

and features of the headlining were examined before the selection of the optimum

material, which can be used for the manufacturing of headlining. ABS has been

selected to manufacture the headlining with the method of thermoforming because of

the common material using for automotive interior parts

3.2.2. Manufacturing Process Selection Criteria

It is an important challenge for design and manufacturing engineers to select

the right manufacturing process for the production of a part, the reason being that

design and manufacturing engineers have so many choices in terms of raw materials

and processing techniques to fabricate the part. This section briefly discusses the

criteria for selecting a process. Selection of a process depends on the application

need. The criteria for selecting a process depend on the production rate, cost,

strength, size and shape requirements of the part, as described below.

In this study, selection criteria of CES selector have been used to find the best

manufacturing process and compatible material. The best materials to be used for

production are sometimes not applied owing to the selection of non-producible

method, or because of high investment cost, incompatibility between shape and

production method. By means of Ashby’s method (CES selector), alternative

materials have been chosen, and then compatibility between manufacturing method

and material will have been searched. After these processes, alternatives for materials


40

and manufacturing methods have been evaluated by considering the following

parameters.

Production Rate/Speed: Depending on the application and market needs, the

rate of production is different. For example, the automobile market requires a high

rate of production. Similarly, there are composites manufacturing techniques that are

suitable for low-volume and high-volume production environments.

Cost: Most consumer and automobile markets are cost sensitive and cannot

afford higher production costs. Factors influencing cost are tooling, labor, raw

materials, process cycle time, and assembly time. The cost of a product is

significantly affected by production volume needs as well.

Performance: Each composite process utilizes different starting materials

and therefore the final properties of the part are different. The strength of the

composite part strongly depends on fiber type, fiber length, fiber orientation, and

fiber content (60 to 70% is strongest, as a rule).

Size: The size of the structure is also a deciding factor in screening

manufacturing processes. The automobile market typically requires smaller-sized

components compared to the aerospace and marine industries. For small- to medium-

sized components, closed moldings are preferred, whereas for large structures such

as a boat hull, an open molding process is used.

Shape: The shape of a product also plays a deciding role in the selection of a

production technique.

3.2.3. Design for Excellence (DFX)

A key part of any product realization process is the robustness of the design.

Many "Design for" initiatives such as Design for Assembly, Design for Cost, Design

for Manufacturing, Design for Test, Design for Logistics, Design for Performance,

and so on are now being referred to as Design for Excellence (DFX). There is a

strong customer focus at the product-planning phase and in the product evaluation

phase of the product development process. The overall product development process

is rooted Market-in refers to having a clear set of customer-driven requirements as


41

the basis for product development. This is a fundamental requirement for DFX.

Concurrent engineering of product design and development activities provides the

second main step in achieving DFX (KUO, 2001).

A successful DFX process requires carefully managed design of new

products. Numerous activities must be coordinated in order to develop and

implement a successful product realization effort. Information must be gathered and

analyzed from regions of the globe in which products will be introduced, and

products must be market-tested in those specific regions. Technology development

activities must operate in parallel with product technology planning and market

development planning to assure timely development and introduction of new

products.

In DFX, “X” means excellence and shows all of demands about product

required by whole customers. Expectations of customer from “X” can be quality, low

cost, performance, reliability, lightweight for minimum fuel consumption,

maintenance, service life etc.

In this study, the common appearance of bumper has been changed according

to the feedback taken from customers. The main problem was the service cost of

bumpers after crashworthiness, therefore maintenance cost plays a significant role on

customers. Three pieces bumper design has been used to minimize collision

problems. If you have any accident from front or rear, you will change only damaged

parts that are from right, left, or middle bumpers. This provides cost reducing after

accident for customers. Therefore, three-piece bumper instead of one-piece bumper

has been used in the vehicle. For these reasons, shape factor, alternative

manufacturing methods, size, and alternative material numbers have been changed

using the DFX design technique.

3.2.4. Design for Manufacturing and Assembly (DFMA)

Design for Manufacturing (DFM) and design for assembly (DFA) are the

integration of product design and process planning into one common activity. The

goal is to design a product that is easily and economically manufactured. The


42

importance of designing for manufacturing is underlined by the fact that about 70%

of manufacturing costs of a product (cost of materials, processing, and assembly) is

determined by design decisions, with production decisions (such as process planning

or machine tool selection) responsible for only 20%. The heart of any design for

manufacturing system is a group of design principles or guidelines that are structured

to help the designer reduce the cost and difficulty of manufacturing an item.

In this study, first of all, metal parts inside the bumper and fender have been

changed by composite materials and the parts are produced by using composite

manufacturing methods. Furthermore, total number of sub-parts and fabrication time

are decreased by increasing multi-functional part numbers and handling operations.

The same effects have been appeared in headlining design changing. Thermoplastic

materials instead of thermoset materials have been taken in use with new design that

is suitable for thermoplastic material manufacturing method. With this improvement,

part cost decreased, modularity increased, multi-use and multi-functionality have

been improved, by considering the following rules (Chang, Wysk, and Wang, 1998)

Reduce the total number of parts. The reduction of the number of parts in a

product is probably the best opportunity for reducing manufacturing costs. Less parts

implies less purchases, inventory, handling, processing time, development time,

equipment, engineering time, assembly difficulty, service inspection, testing, etc. In

general, it reduces the level of intensity of all activities related to product during its

entire life. A part that does not need to have relative motion with respect to other

parts does not have to be made of a different material, or that would make the

assembly or service of other parts extremely difficult or impossible, is an excellent

target for elimination. Some approaches to part-count reduction are based on the use

of one-piece structures and selection of manufacturing processes such as injection

molding, extrusion, rotational molding, among others.

Develop a modular design. The use of modules in product design simplifies

manufacturing activities such as inspection, testing, assembly, purchasing, redesign,

maintenance, service, and so on. One reason is that modules add versatility to

product update in the redesign process, help run tests before the final assembly is put


43

together, and allow the use of standard components to minimize product variations.

However, the connection can be a limiting factor when applying this rule.

Using of standard components. Standard components are less expensive

than custom-made items. The high availability of these components reduces product

lead times. In addition, their reliability factors are well ascertained. Furthermore, the

use of standard components refers to the production pressure to the supplier,

relieving in part the manufacture’s concern of meeting production schedules.

Design parts to be multi-functional. Multi-functional parts reduce the total

number of parts in a design. In addition, there can be elements that besides their

principal function have guiding, aligning, or self-fixturing features to facilitate

assembly, and/or reflective surfaces to facilitate inspection, etc.

Design parts for multi-use. In a manufacturing firm, different products can

share parts that have been designed for multi-use. These parts can have the same or

different functions when used in different products. In order to do this, it is necessary

to identify the parts that are suitable for multi-use. The goal is to minimize the

number of categories, the variations within the categories, and the number of design

features within each variation. The result is a set of standard part families from which

multi-use parts are created. After organizing all the parts into part families, the

manufacturing processes are standardized for each part family.

Design for ease of fabrication. Select the optimum combination between the

material and fabrication process to minimize the overall manufacturing cost. In

general, final operations such as painting, polishing, finish machining, etc. should be

avoided. Excessive tolerance, surface-finish requirement, and so on is commonly

found problems that result in higher than necessary production cost.

Minimize handling. Handling consists of positioning, orienting, and fixing a

part or component. To facilitate orientation, symmetrical parts should be used when

ever possible. If it is not possible, then the asymmetry must be exaggerated to avoid

failures. Use external guiding features to help the orientation of a part.


44

3.2.5. Test Methods for Composite Materials

Samples of composite materials are subjected to a wide variety of mechanical

tests to measure their strength, elastic constants, and other material properties as well

as their performance under a variety of actual use conditions and environments.

Physical tests have been carried out for samples to measure water absorption and

ignition loss of cured reinforced resins. Vicat softening temperature test and heat

deflection temperature test results have been used to evaluate thermal properties of

selected materials for two primary purposes: 1) engineering design (for example,

failure theories based on strength, or deflections based on elastic constants and

component geometry) and 2) quality control either by the materials producer to

verify the process or by the end user to confirm the material specifications.

If a material is going to be used as part of an engineering structure that will

be subjected to a load, it is important to know that the material is strong enough and

rigid enough to withstand the loads that it will experience in service. As a result,

engineers have developed a number of experimental techniques for mechanical

testing of engineering materials subjected to tension, bending, and torsional loading.

In this study, exterior and interior trimming parts have been exposed different

kind of testing methods. Exterior trimming parts have been tested to check the

various features of materials such as extinguisher properties, chemical properties,

mechanical properties, physical properties, and thermal properties. Burning

Behaviour Test, Wear Resistance Test, Thermal Shock Test, Heat Cycle Test, Heat

Aging Test, Impact Resistance Test, Tension Test, Vicat Softening Test, Melting

Test, UV Resistance Test (Weathering Test ), Chemical Resistance Test have also

been performed to test the behaviour of interior trimming parts under different

service conditions. The testing methods used for interior and exterior trimming parts

have been explained in following sections.


45

3.2.5.1. Tension Test

In this study, tension test results are so important to be evaluated the

mechanical properties of composite based automotive components. Parts

manufactured by composite manufacturing methods were controlled by force,

minimum 110 MPa, carried on specimens. Specimens were placed in the grips of a

Shimadzu Autography test device shown in Figure 3.3 at a specified grip separation

and pulled until failure. Test speed for composite test specimens have been set up as

2 mm/min. The shape and dimensions of the test specimen are shown in Figure 3.4,

have been designed according to ISO/FDIS 527-4.

The most common type of test used to measure the mechanical properties of a

material is tension test. Tension test is widely used to provide basic design

information on the strength of materials and is an acceptance test for the specification

of materials. The major parameters that describe the stress-strain curve obtained

during the tension test are the tensile strength (UTS), yield strength or yield point

(σy), elastic modulus (E), percent elongation (ΔL%) and the reduction in area

(RA%). Toughness, resilience, poison’s ratio (ν) can also be found by the use of this

testing technique. ISO/FDIS 527-1 tensile testing was used to measure the force

required to break a polymer composite specimen and the extent to which the

specimen stretches or elongates to that breaking point. For ISO/FDIS 527-1, the test

speed can be determined by the material specification or time to failure (1 to 10

minutes). An x-y recorder plotted a load elongation curve, so that the tensile behavior

of the material can be obtained. An engineering stress-strain curve can be constructed

from this load-elongation curve by making the required calculations.

Figure 3.3. Shimadzu Autography test device


46

Figure 3.4. Dimension of tensile test specimen used in experiment (ISO/DIS 527-4)

3.2.5.2. Three-Point Bending Test

Composites, selected in this study, have been designed to provide

significantly higher specific stiffness and specific strength (stiffness or strength

divided by material density) - that is, higher structural efficiency- relative to

previously available structural materials. In composite materials, strength and

stiffness are provided by high-strength, high-modulus reinforcements. Three point

bending test has been used to test these type of properties of the selected materials.

Three-point bending test is a well-known mechanical strength test and it

accurately gives properties such as the young’s modulus and the tensile strength of a

material. These properties govern the eventual strength of the tablet and are a

function of amount of compressive force used whilst making the tablet or specimen.

Specimens are placed on the tips of a Shimadzu Autography test device shown in

Figure 3.5 at a specified tips separation and forced until failure. TSE 985 EN ISO

178 bending test standard was used to measure the force required to break a polymer

composite specimen and the deformation to which the specimen bends to that

breaking point. Specimens with 80±2 mm lengths, 10±0.2 mm widths, and 4±0.2 mm

thicknesses have been subjected to three point bending test to check their resistance

against 200 MPa for satisfying results.


47

Figure 3.5. Shimadzu Autography test apparatus for three-point bending test

3.2.5.3. Heat Deflection Temperature (HDT) Test

In this study, HDT test has been used to measure the stress, 10MPa, required

to break a polymer composite specimen under min. 85°C and the deformation to

which the specimen bends to that breaking point. The value obtained for a specific

polymer grade will depend on the base resin and on the presence of reinforcing

agents. Deflection temperatures of glass fiber reinforced engineering polymers often

approach the melting point of the base resin. The heat deflection temperature test

results are a useful measure of relative service temperature for a polymer when used

in load-bearing parts. However, this is a short-term test and should not be used alone

for product design. Other factors such as the time of exposure to elevated

temperature, the rate of temperature increase, and the part geometry all affect the

performance. The deflection temperature is a measure of a polymer's resistance to

distortion under a given pressure at elevated temperatures. The deflection

temperature is also known as the deflection temperature under load (DTUL), 'heat

deflection temperature', or 'heat distortion temperature' (HDT). The two common

loads used are 0.46 MPa and 1.8 MPa, although tests performed at higher stesses

such as 5.0 MPa or 8.0 MPa are occasionally encountered. In this study, safety factor


48

has been increased to keep in safety side to automotive components used. For this

reason, 10 MPa stress was applied to the specimens. The common ASTM test is

ASTM D 648 while the analogous ISO test is ISO 75. The test for 1.8 MPa stress is

performed under ISO 75 Method A while the test using a 0.46 MPa stress is

performed under ISO 75 Method B. HDT test device is shown in Figure 3.6.

Figure 3.6. a. HDT test device, b. Quadrant Engineering Plastic Products test

geometry

3.2.5.4. Barcol Hardness Test

In this study, Barcol hardness test is performed according to TS EN 59

standard. The main goal is to find the gel coat thickness on the automotive

components. Approximately sixty measurements have been made to calculate

standard deviation and average value. The measured the gel coat thickness on the

surface of part has been used to get extra information about curing process time and

using gel coat properties. Generally, gel coat provides the resistance factor on a part

that produced by composite materials. For a good final production, Barcol hardness

must be greater than 50 Barcol

The Barcol hardness test characterizes the indentation hardness of materials

through the depth of penetration of an indentor, loaded on a material sample and

compared to the penetration in a reference material. The method is most often used

for composite materials such as reinforced thermosetting resins or to determine how

much a resin or plastic has cured. The test complements the measurement of glass


49

transition temperature, as an indirect measure of the degree of cure of a composite. It

is inexpensive and quick, and provides information on the cure throughout a part.

The Barcol hardness test is generally used on soft materials such as rigid plastics

(min 1.5 mm thickness). It measures hardness based on indentation of a sharp point

with a flat tip. The test is performed using a similar method and indentation device,

shown in Figure 3.7. It is used to measure Shore D hardness value by using a round

tip indentor. Barcol hardness is not a valid hardness measure for curved surfaces.

During the test, the plastic sampling to be tested is placed just below the steel

indenter of the Barcol Tester and a uniform pressure is applied on it until the dial

indicator touches a stable maximum. The scale giving a direct reading of the depth of

the penetration transforms it into definite Barcol numbers like 934-1. Barcol

hardness is measured on a scale from 0 to 100 with the typical range being between

50B and 90B. A measurement of 50-60B is roughly equivalent to a Shore hardness of

70-80D or a Rockwell hardness M100.

Figure 3.7. Barcol Test device (Barber-Colman)

3.2.5.5. Burn off Test

In this study, FRP specimens were subjected to Burn off Test to determine

information about fiber volume content, resin content, the number of fiber layers, and

orientations. Burn off Test gives physical results about specimen or automotive

component’ including materials. As we know, including material amounts and

material orientation give us information about mechanical properties of specimen.


50

The tests were carried out in general accordance with ASTM D2584. The

specimen contained in a crucible is ignited and allowed to burn until only ash and

carbon remain. The carbonaceous residue is reduced to an ash by heating in a muffle

furnace at 565°C, cooled in desiccators, and weighed. The heat from the oven is used

to burn the resin matrix, leaving the fiber layers exposed. The oven used for burnoff

testing is shown in Figure 3.8. The specimen shall weigh approximately 5 g with a

maximum size of 2.5 by 2.5 cm by thickness.

Figure 3.8. Burn off test oven

3.2.5.6. Burning Behaviour Test

In this study, burning behaviour test have been carried out on ABS test

specimens for interior trimming parts. The result of the burning behaviour test shall

be considered satisfactory if, taking the worst test results into account, the horizontal

rate is not more than 100 mm/min or if the flame extinguishes before reaching the

last measuring point. Burning behaviour of materials used in the interior construction

of certain categories of motor vehicle is according to the 95/28/EC directive. In the

burning behaviour test, some of the preparations have been made; ABS thermoplastic

samples with napped or tufted surfaces have been placed on a flat surface and

combed twice against the nap using the comb. Then the samples were placed in the

sample holder so that the exposed side could be downwards to the flame. On the

other hand, the gas flame has been adjusted to a height of 38 mm using the mark in

the chamber as the air intake of the burner being closed. Before starting the first test,


51

the flame was burned at least for 1 min for stabilization. The sample-holder was

pushed into the combustion chamber so that the end of the sample was exposed to the

flame, and the gas flow was cut off after 15 seconds. The measurement of the

burning time was started at the moment when the foot of the flame passed the first

measuring point. The flame propagation was observed on the side burning faster than

the other; upper, or lower side. Measurement of burning time was completed when

the flame has come to the last measuring point or when the flame extinguished

before coming to the last measuring point. The thickness of the sample as shown in

Figure 3.9 corresponds to the thickness of the product to be tested. It shall not be

more than 13 mm but in this study, 3 mm specimens have been used for simulating

the part thickness.

Figure 3.9. The shape and dimensions of the burning behaviour test specimen used in experiment (95/28/EC, 2007)

3.2.5.7. Melting Test

In this study, ABS thermoplastic specimens were used in the melting test.

The evaluation criterion is the cotton’ status that was placed in the chamber before

the test. This shows us that any material can be used on vehicle but it must be under

control to satisfy the requirements came from regulations. In any burning situation on

vehicle, material can be melted by heat or fire but it does not need to provide directly

or indirectly increasing effect on the burning. This test is used to determine the

melting behaviour of materials according to 95/28/EC directive. In the test, the

sample was placed on the support and the latter was so positioned that the distance


52

between the surface of the radiator and the upper side of the sample was 30 mm. The

receptacle, including the cotton wool, was placed beneath the grill of the support at a

distance of 300 mm. The radiator was put aside, so that it could not radiate on the

sample, and switched on. When it was on full capacity it was positioned above the

sample and timing was started. If the material have been melted or deformed, the

height of the radiator was modified to maintain the distance of 30 mm. If the material

was ignited, the radiator was put aside three seconds afterwards. It was brought back

in position when the flame extinguished and the same procedure was repeated as

frequently as necessary during the first five minutes of the test. After the fifth minute

of the test: (i) if the sample has extinguished (whether or not it has ignited during the

first five minutes of the test) leave the radiator in position even if the sample have

been reignited. (ii) If the material was burning, await extinction before bringing the

radiator into position again. In either case, the test must be continued for an

additional five minutes. The test samples have been prepared as 70 mm x 70 mm

dimensions at 3 mm thickness

3.2.5.8. UV Resistance Test (Weathering Test)

In this study, weathering test has been applied according to JIS D 0205 on

ABS specimens that were prepared the dimensions of 70x70x3 mm. The following

test conditions were applied, which was continual irridation from the light source,

with an intensity of 0.5 W/m² at 340 nm. This corresponded to 550 W/m² in the

frequency range of 290nm to 800 nm, lambda. The black standard temperature,

relative humidity and wetting time was set up 63±3°C, 50 % ± 5%, and 18 min± 0, 5

min. respectively. The test panels have been moved so that they had equal time at

each height in the turntable, to give equal exposure. Exposure time has been adjusted

as 300 hours and the results have been controlled according to JIS L 0207.

It is important to note that correlation between test results from accelerated

aging and outdoor exposure is not exact and is only valid for specific types of

material and for specific properties where such correlation is based on known

experience. The correlation factors for accelerated aging tests could very well be


53

different for different types of plastics materials. Light from the xenon lamp was

filtered to give a spectral distribution that is as close as possible to natural sunlight.

The spectral light intensity between 290 nm and 800 nm is defined as 100%.

A suitable filter is borosilicate glass, used for internal and external filters. The

characteristics of the xenon lamp and filters changed during the aging test. For this

reason, the filters need to be changed at suitable intervals, as recommended by the

manufacturer. The equipment must have a radiometer that measures the light

intensity on the test surface. Light intensity has been checked regularly with a

calibrated xenon lamp and suitable calibration interval is 600-700 hrs.

Since the degradation of polymer material is affected by temperature, it is

important that the temperature should be carefully controlled during testing. The

temperature was controlled by means of a black-standard thermometer mounted on

the rotating specimen holder so that it was exposed in the same way as the test

pieces. The temperature indicated by the black standard thermometer corresponds

with temperature of a dark test surface of thermal conductivity. The surface

temperature of an object with good thermal conductivity will commonly be lower

than for a black-standard thermometer. The black-standard thermometer consists of

stainless steel plate of approximately 1 mm thickness. The plate surface facing the

light surface facing the light source was covered with an even black coating of good

aging resistance. The black painted surface should absorb at least 95 % of all

radiation from the light source up to 2500 nm. The surface temperature was

measured with a platinum resistance sensor. The steel plate was insulated with a 5

mm thick polyvinylidene fluoride (PVDF) backing plate. The paint on a black-

standard thermometer has been checked regularly. The relative humidity of the air in

the test chamber has been measured and controlled at the set value. The sensor,

which measured relative humidity, must be shielded from the light emitted by the

lamp. The chamber must have spray nozzles that permit evenly distributed wetting in

the test pieces shall be wettes inetermittently with distilled or deionised water during

the test cycle. The water must not leave patches or residues on the surface. The water

shall have conductivity not exceeding 5μS/cm and must not have more than 1 ppm of

solid content.


54

Figure 3.10. Xenon test device used in weathering test

3.2.5.9. Heat Cycle Test

In this study, heat cycle test has been performed for interior trimming

samples based on thermoplastic as three cycles as shown in Figure 3.11. Interior

trimming parts always stay in different heating ventilating and air conditioning

behaviour. For this reason, these conditions need to be simulated on specimens

before mounted on the vehicle in the quality laboratory conditions. All of the test and

test conditions were carried out according to ES-X60210 standard and test specimens

have been taken from finished products as 200x70x3 mm Appearance changes on the

specimen after the test such as break, discolor, deformation and function failure were

evaluated after three cycles. Further as reference appearance change during heat and

cold resistance test and the change of dimension and gap have been measured. Three

cycles for heat cycle test are explained in the following:

1. Heat Resistance: Surface temperatures on the specimens, 80±2°C for three hours

2. Cold Resistance: all specimens have been exposed at -30±2°C for three hours

3. Humidity Resistance: all specimens have been stayed at 50±2°C and 90% relative

humidity for seven hours or more


55

Figure 3.11. Heat cycle test application sketch (ES-X60210, 1996)

3.2.5.10. Thermal Shock Test

In this study, Thermal Shock Test has been carried out according to ES-

X83215 standard for interior trimming parts based on thermoplastic. Thermal shock

test specimens had the dimensions of 200x70x3 mm have been placed in an oven for

3 minutes at “heat resistance” temperature specified in material specification

according to ES-X60210 as shown in Figure 3.11. Then the specimens were removal,

and allowed to stay at room temperature for 10 minutes. The explained process was

considered as one cycle and have been repeated as 5 cycles to the same specimens to

be seen the final test results. Thermal shock test were happened to be faced the

temperature differences on the interior trimming parts.

3.2.5.11. Heat Aging Test

In this study, heat aging test has been made on ABS samples specified as

200x70x3 mm. Material behaviors for interior trimming parts have been observed for

various temperatures in different time interval. Finally, visual differences such as

color changing, break and deformation after test have been evaluated by means of


56

ES-X60120. Heat aging test specimens have been placed in an oven under the test

condition specified, at 80±2°C and for 300 hours. Then the test specimens were upon

removal from the oven, applied visual inspection. Instrument panel was tested with

all parts equipped before the heat aging test to be seen the working conditions to be

true or not because of object temperature value is significant. After the heat aging

test, all specimens have been evaluated according to physical appearances by visual

inspection. Specimens, three numbers, have been selected from equivalents made

under the identical conditions with the finished products.

3.2.5.12. Chemical Resistance Test

In this study, chemical resistance test has been used to evaluate the

performance of interior trimming parts by means of working visual examinations

such as deformation, color changing, tear, and break according to ES-X60120

Various chemicals such as grease and luster wax were used in chemical resistance

test. In test, the specimen had the dimensions of 70x70x3 mm have been wiped off

with a cloth soaked a chemical specified by grease and luster wax. Then specimen

was allowed standing 1 hour under the condition specified in laboratory: 23±2°C and

50±5% relative humidity. The specimen was inspected and evaluated by visual.

Because of the any problem seen on the specimen, again specimen have been placed

it further for 3 hrs in an oven at 70°C. Specimen was upon removal from the oven,

inspected, and evaluated. Specimen has been taken from equivalents made under the

identical conditions with the finished products.

3.2.5.13. Abrasion Resistance Test

In this study, abrasion resistance test has been applied on the conditions

specified in ES-X60120 standard for interior trimming material, ABS. Test specimen

made under the same condition with the finished product has been rubbed in

specified conditions, shown in Table 3.4. The specimens have 3 mm thickness, in

disk shape diameter, φ: 100 mm and center hole φ: 8 mm, has been prepared and set


57

it on the chuck rotating, 60 rpm, constantly with stable speed. Specimen was driven

sand wheel rotated, shown in Figure 3.12, to rub the specimen to judge the difference

of weights before and after abrasion, or determine the condition of surface to know

the abrasion quality of specimen. Appearance after wear resistance test on the test

specimen has been evaluated as shown in Table 3.5.

Figure 3.12. Abrasion test device used for interior trimming parts

Table 3.4.Wear Resistance Test conditions (ES-X60120) Items Conditions Weight (g) 500 including a wear head Stroke (mm) 100 Rub rate (cycles/min) 30 Material of canvas 10 Normal canvas # 10 (JIS L 3102(Cotton canvas)) Wear head Refer to Figure 3.11 Cycles 500 (reciprocating)

Table 3.5. Evaluated conditions for wear resistance test (ES-X60120) Grade Appearance

5 Free of wear 4 Slightly wear 3 Wear, but not remarkably 2 Wear 1 Remarkable wear


58

3.2.5.14. Drop Impact Test

In this study, Impact Resistance testing is a way of rating the resistance of the

interior trimming parts to cracking or breakage when struck by an impact force.

Evaluation criteria have been chosen from visual expectations such as deformation,

crack, and no color changing. The impact resistance test was carried out according to

ASTM D 2444 standard. The specimen with dimension of 100x100x3 mm was

placed under the guide tube in the required holder, and the tup was raised to the

height of 1 m above the top surface of the part. The tup was allowed to fall free and

strike the specimen, and was caught by the cable before it can bounce and strike the

specimen again. The specimen was then inspected for any signs of cracking or

failure.

3.2.5.15. Vicat Softening Test

In this study, Vicat softening test have been carried out according to TES EN

ISO 306, for which they give a measure of the temperature at which the

thermoplastics start to soften rapidly. The Vicat softening temperature is the

temperature at which a flat-ended needle penetrates the specimen to the depth of 1

mm under a specific load. The temperature reflects the point of softening to be

expected when a material is used in an elevated temperature application. ABS test

specimen was placed in the testing apparatus so that the penetrating needle rested on

its surface at least 1 mm from the edge. A load of 10N was applied to the specimen,

shown in Figure 3.13 as schematic view of test apparatus. The specimen was then

lowered into an oil bath at 23°C. The bath was raised at a rate of 120°C per hour

until the needle penetrates 1 mm. The test specimen has been obtained from ABS

thermoplastic materials, 3 mm thick with flat surface and 10 mm in width and length.

The Vicat softening test determined the temperature at which the needle penetrated 1

mm. Two test specimens were used to test each sample.


59

Figure 3.13. Apparatus with a direct-contact heating unit (TS EN ISO 306)

3.2.6. Ashby Method and Material Selection Software CES

In this study, CES EduPack 2005 Materials Selection software was used as

the primary tool to provide the technical support for the analysis, conclusions, and

comments. The ‘Cambridge Materials Selector’ (CMS) is a computer package

consisting of a database of material properties, a management system, which

recovers and manipulates the data, and a graphical user interface, which presents the

property data as material selection charts. The approach employs a number of novel

features.

The CES EduPack 2005 materials selection software used to explore several

topics presented in Ashby text and highlighted as follows; general requirements of

the materials universe, use of material selection charts, translation of design

problems into engineering terms (or material properties tabulated in the software),

derivation and use the material indices, exploration of the process universe, advanced

concepts including multiple constraints and objectives, and selection of material and

shape were studied with the CES software.


60

To select a material, the user performs a series of selection stages. On each

stage, a pair of material properties (or user-defined functions of material properties,

like E½ / r) is specified. The program generates a graph with these properties as the

axes. All materials contained in the database with applicable data entries are plotted

on the graph. The user specifies the area of the graph, which satisfies the selection

criterion, and the materials that lie in that area are considered to have ‘passed’ the

selection stage. Up to six independent selection stages can be performed. The

program stores the results of each selection stage and these can be examined at any

time. It is possible to modify any selection stage so that performance criteria can be

tightened or relaxed until suitable materials are found. A summary of the CMS

session can be stored in a disk file and read into the package later. This enables users

to continue/modify a selection where they left-off and to re-evaluate the selection

criteria in the light of other design information. It also documents the selection

process. A number of data manipulation routines are available during each selection

stage. These include zooming-in on an area of the graph, listing the properties of

particular materials, and displaying the materials, which passed all the previous

stages. Facilities are available for plotting hard copies of graphs and listing text

information (Cebon and Ashby, 1992).

Following procedures have been followed for the selection of materials and

compatible manufacturing methods for bumper, fender, and headlining used in buses.

1. The Design Process: The process was to consider what had to be

accomplished and to look for different ways of doing it. In the design of automotive

components, such traditional thinks as the fender, bumper, headlining have been

looked at by considering a different ordering and structuring of components. Design

process and material relationship are shown in Figure 3.14.

2. A strategy for material selection has been developed: At each stage of

design from conceptual to detailed, materials data were needed, but the type of data

was different and was obtained more precise and less broad as the final design was

approached, shown in the Figure 3.15.


61

Figure 3.14. Relationship among design requirements, material, and process needs (Ashby, 2005)

Figure 3.15. Relationship between design flow chart and material (Farag, 1997)

3. Ashby’s material selection strategy includes four steps as shown in Figure

3.16. Design requirements were translated to express function, objectives,

constraints, free variables, screen using constraints; eliminated the materials couldn’t

do job, rank using objective; found the screened materials that went the job best, seek

supporting information and researched the family history of top ranked candidates.


62

Figure 3.16. Ashby’s material selection strategy in four steps (Ashby, 2005)

4. The design table for material and manufacturing method selection has been

developed by describing function, constraints, objective, and free variables.

5. An appropriate material index (M) for exterior and interior components have

been established, that is, the simplified model has been determined to be best for my

work.

6. Material index and the CES software were used for finding candidate materials.

Materials selection charts including limit stages, graph stages have been specified for

exterior and interior components and candidate materials and manufacturing methods

have been explained.

7. As part of the evaluation of material choices has been commented on, the choices

yielded by the CES software, and added any practical insight into minimizing and/or

optimizing the parts. Interaction between function, material, shape, and process was


63

looked at. Manufacturing processes have been commented on for the candidate

materials, i.e., what process and general information from the CES Process universe

record. On the other hand, other considerations found important have been evaluated,

e.g. shape factor (material dependent), elongation, section thickness, roughness etc.

8. Alternative material selection processes and candidate materials were reflected

and written a summary statement on the strategy for materials selection and

conclusions.

3.2.7. Material Index for Exterior and Interior Trimming Parts

Material index is a combination of materials properties that characterizes the

performance of material in a given application.

In this study, cross-section areas determining material index are taken from

bumper, fender and headlining. All of the parts’ cross-section areas have been

observed to resemble to beam as shown in Figure 3.17. Material Indices have been

plotted and used for material selection charts on the graph stage to describe the exact

areas. Material indices have been calculated by means of bending stiffness (3.1).

Objective of material indices (3.2) has been defined as lightweight material, but in

general, it defines as plots of one material property or a combination of material

properties against another. Ranking has been achieved by the use of material indices

derived from the objective. These were grouping of material properties that

characterized performance: The materials with the largest values of an index

maximized some aspect of performance.

Figure 3.17. Stiff beam length L and minimum mass (Ashby, 2005)


64

Function: Beam

Constraints: Length (L) is specified. Bending stiffness must be greater than S*

Equation for constraint on A: (3.1)

Objective: Minimize mass (m) (3.2)

Eliminate A in (2) using (1):

Free Variables: Material choice and section area A.

Performance Metric:

Material index of selected materials:

3

2

3 12LCEA

LCEIS ==

ρ

21

EM =

4.RESULTS AND DISCUSSIONS Murat ÖNŞEN

65

4. RESULTS AND DISCUSSIONS

4.1. Material Selection

Alternative materials and manufacturing processes have been selected with

the aid of the CES selector’ assistant stages of limit and graph stages by following

the steps described below:

1. Define the design requirements

2. Develop the material index (M) and limits

3. Show materials selection charts / tables as limit and graph stage

4. Justify / comment on various aspects of candidate materials

4.1.1. Material and Process Selection for Exterior Trimming Parts

In this study, two different types of exterior trimming parts such as bumper

and fender have been selected. These components are mounted on different side of

the vehicles, but material requirements are the same in service condition. The design

requirements for bumper and fender have been defined as shown in Table 4.1. These

requirements include function, constraints, objective, and free variables. Constraints

used in alternative material selections are obtained from mechanical, physical, and

thermal test results. Values determined as constraints were added to the requirements

table to be evaluated after the selection.

Table 4.1. Defined design requirements for bumper and fender Function Bumper Objective Weight reduction to decrease fuel consumption

Constraints

§ Thickness, max 3 mm § Hardness, min. 50 Barcol § Fiber mixing ratio, min. 30% § HDT, min 85˚C@ under 10N force § Bending test(stiffness), min 200 MPa § Tension test, min.110 MPa § Corrosion resistance § Service temperature -30°C < T < 80°C

Free variables § Material


66

Material index has been found as 2 by following the procedure explained in

previous chapter. Candidate materials and material properties have been shown in

Table 4.2. CFRP, GFRP, aluminum alloy (AA), high carbon steel (HCS), mild

carbon steel (MCS), stainless steel(SS) are selected as alternative materials for

bumper and fender. The properties of these materials are then obtained from

technical documents and material sheets.

Table 4.2. Properties of alternative materials for bumper and fender

MATERIAL CFRP GFRP Al alloy

High Carbon

Steel(4340)

Mild Carbon

Steel(1020) Stainless Steel(304)

Density (kg/m³) 1800 1550 2710 7900 7860 8000

Young Modulus (GPa) 230 80 73 210 210 210

Stiffness (E⅓/ρ) (GPa) 30 73 10 30 210 210

Cost (Euro/kg) 45 9 1.3 0.4 0.4 4

Elongation at break (%) 1.8 3 12 15 25 55

Tensile strength (MPa) 3530 2400 90 190 380 590

4.1.1.1.CES Selector on Limit Stage for Exterior Trimming Parts

CES selector’ limit stage has been used to select alternative materials. Limit

stage works by input and output principle and technical information that are related

to material properties such as physical, electrical, thermal, mechanical, optical, etc.

When material properties for every row and column are added to limit stage,

alternative material numbers are reduced to approaches to the best results.

Information needed for the inputs have been taken from material universe of CES

selector. Material universe are provided the minimum and maximum values for

materials such as CFRP, GFRP, high carbon steel, medium carbon steel, stainless

steel. Some of material properties such as mechanical, physical, optical, etc. related

by bumper and fender are added to Appendix between one and six sections.

Initially, 91 different alternative materials have been determined from level 2

grade of CES selector. Then, the numbers of alternative materials, shown in Figure

4.1, has been reduced to 34 by entering minimum and maximum values of density

(1500 kg/m³ and 8100 kg/m³) and cost (0.3 Euro/kg and 72 Euro/kg) in limit stage.


67

The numbers of alternative materials are still too much. The reduction has been

continued by considering the mechanical properties as shown in Table 4.3. After this

step, the numbers of pre-selected materials have been reduced to 20 as shown in

Figure 4.2.

Table 4.3. Mechanical properties used for exterior parts in limit stage (CES, 2005) Mechanical Properties Unit Min. Value Max. Value Young' Modulus Gpa 15 216 Shear Modulus Gpa 6 85 Bulk Modulus Gpa 15 200 Poisson's Ratio 0,265 0,36 Hardness as Vickers Gpa 0,11 5,5 Elastic Limit Gpa 0,09 9 Tensile Strength Gpa 0,11 2,24 Compressive Strength Gpa 0,09 1,76 Elongation % 0,36 70 Endurance Limit Gpa 0,06 0,75 Fracture Toughness Gpa.m½ 0,006 0,15 Loss Coefficient 0,0001 0,005

When thermal values; service temperatures between-100 and 300°C, optical

property; transparency, processability properties that includes scales between 1 as

impractical and 5 as excellent; mouldability between 4 and 5 and machinability

between 1 and 3, and durability properties such as flammability, fresh water, weak

and strong acid resistance, weak and strong alkalis, organic solvents, UV, oxidation

at 500°C are added to limit stage, two different materials, namely GFRP and CFRP

are obtained. The properties of these two materials are shown in Figure 4.3, Figure

4.4, and Figure 4.5.


68

Figure 4.1. Alternative materials found after entering minimum and maximum density and cost values in limit stage of CES (CES, 2005)

Figure 4.2. Alternative materials obtained after entering minimum and maximum requirements for mechanical properties (CES, 2005)


69

Figure 4.3. Thermal and electrical properties of candidate materials (CES, 2005)

Figure 4.4. Optical, Processability, Durability values of the candidates (CES, 2005)


70

Figure 4.5. Durability values of the candidate materials (CES, 2005)

4.1.1.2.CES Selector on Graph Stage for Exterior Trimming Parts

Inputs required for graph stage are obtained from material universe of CES

selector. Inputs and outputs are used in graph stage too. Nevertheless, unlike the limit

stage, inputs have numeric values while outputs have graphical appearance in graph

stage. Information obtained for candidate materials has been obtained from specified

graphical area. Therefore, numbers of alternative material outputs generally are more

than the results of the limit stage. Material numbers are related to material index and

its working area. Material index are movable to upper and lower according to slope

angle. Every movement reduces or increases the working area and selected

alternative material numbers. Material index on Density vs. Young’s modulus graph

stage and assistance lines that come from upper and lower limits of alternative

material properties are shown in Figure 4.6.

There are about 2882 candidate materials, which could be chosen as

alternative exterior materials. By means of second helping line near material index

related to minimum value of young’s modulus, 15 GPa, specified working area has

been determined by vertical slope lines as shown in Figure 4.7.


71

Figure 4.6. Density vs. Young’ modulus for exterior trimming parts (CES, 2005)

Figure 4.7. Specified working area on young’ modulus vs. density graph stage (CES, 2005)

After the restriction of the specified working area, the numbers of alternative

materials have been reduced to 150 materials as shown in Figure 4.8.


72

Figure 4.8. Alternative materials on young’ modulus vs. density graph stage (CES, 2005)

These alternative materials include polymers; derivative of polymers;

different kind of fibers such as carbon, aramid, etc.; different kinds of metallic

materials like Ti, Mg, etc.; ceramic-based materials; woods such as oak, plywood.

For this reason, alternative materials were searched on the graph stage list and

alternative materials obtained after evaluation as GFRP, CFRP, fiber-reinforced

alumina, and some of thermoplastics with and without reinforcements. CFRP is a

high cost alternative materials for bus industry because of the low production range.

CFRP is generally used as sports group of automotive components, for instance, F1

racing car. Fiber reinforced alumina is a new approach and it has been used in bus

manufacturing company as composite materials for 10 years in USA. GFRP is the

best choose for automotive industry, especially bus industry. It has so many different

kinds of materials and production methods that can be used in automotive industry

because of low investment cost, fast prototyping, lightweight, high strength and

stiffness properties when compared to metal.


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Both of criteria such as cost and weight were evaluated by means of

calculation of weight and cost of parts. The weight of fender and bumpers such as

front, middle, and rear were calculated by Catia V5 R19, shown in Figure 4.9 and

dimensions as shown in Figure 4.10 for bumper, and shown in Figure 4.11 for

fender, because of having asymmetric shapes and approaching exact values. Exterior

trimming components’ cost and weight values are shown in Table 4.4 for bumper

and Table 4.5 for fender. Right bumper volume like left bumper was calculated as

0.0012 m³ while middle bumper volume was calculated as 0.0014 m³. The cost and

weight values for alternative materials have been calculated to compare material

suitability. As shown in Table 4.4, CFRP has higher cost value than others while the

weights of the metals were found as higher than composite materials.

Figure 4.9. Bumpers’ 3D models drawn by Catia


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Figure 4.10. Bumpers’ 2D drawings drawn by Catia

Figure 4.11. Fender’s 3D drawing drawn by Catia


75

Table 4.4. Cost and weight values calculated for bumper by Catia

MATERIAL DENSITY kg/m³

COST Euro/kg

BUMPER WEIGHT

(right-left) kg

BUMPER WEIGHT (middle)

kg

TOTAL BUMPER WEIGHT

kg

TOTAL COST

Euro/kg

GFRP 1550 9 1.9 2.3 6.1 54.9 CFRP 1800 45 2.2 2.6 7 315.0

AA 2710 1.3 3.3 4.0 10.6 13.8 MCS 7860 0.4 9.5 11.5 30.5 12.2 SS 8000 4 9.6 11.7 30.9 123.6

Table 4.5. Cost and weight values calculated for fender by Catia

MATERIAL DENSITY kg/m³

COST Euro/kg

FENDER WEIGHT

kg

FENDER VOLUME

m³

TOTAL COST

Euro/kg

GFRP 1550 9 3.1

0.002

27.9 CFRP 1800 45 3.6 162.0

AA 2710 1.3 5.42 7.0 MCS 7860 0.4 15.72 6.3 SS 8000 4 16 64.0

On the other hand, according to pre-selected specified materials,

manufacturing methods were also determined by CES selector. In this work, some of

the important criteria such as mass range, material class, section thickness, shape,

roughness were used to select the best alternative manufacturing processes. Some of

these topics are related to the manufacturing process selection criteria.

To determine the alternative manufacturing method, first of all, mass range

vs. material class graph stage was used. SMC, BMC, transfer moulding for

composite and hybrids materials; compression moulding, injection moulding for

thermoset materials have been found as alternative manufacturing methods (Figure

4.12). Mass ranges for alternative manufacturing method are obtained from process

universe of CES selector.

Section thickness vs. shape class secondly has been used to describe the

manufacturing methods of interior trimming parts due to strong relationship among

the shape selected, thickness, and manufacturing methods. Selection thickness and

material shape are also important parameters for the thermal resistance of the


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material. Generally, increasing section thickness increases thermal deflection

resistance and strength of the part. Alternative processes obtained for section

thickness vs. shape class are shown in Figure 4.13.

Figure 4.12. Pre-processes are shown on mass range vs. material class (CES, 2005)

The best alternative manufacturing methods for exterior and interior parts

have been determined by means of section thickness intervals including minimum

and maximum values as shown in Figure 4.14. Compression moulding, BMC, SMC,

transverse moulding, and injection moulding have been obtained as alternative

processes. The best material thickness interval is determined between 2 and 5 mm for

automotive components as shown in Figure 4.14. In these intervals, the closed

moulding processes have been found as optimum alternative manufacturing method

related to section thickness vs. shape class according to graph stage. Closed

moulding processes generally are used for production of complex parts in automotive

industry. Investment cost is so high when compared to open mould applications, but

final material quality related to finishing and mechanical properties are higher than

open moulding operations. On the other hand closed mould applications reduce the


77

component numbers, handling operations, increase the modularity, multi-

functionality, and multi-use. Therefore, the composite parts are generally produced

by using closed molding due to the excellent tolerance levels obtained on the parts.

Figure 4.13. Alternative processes on section thickness vs. shape class (CES, 2005)

Roughness is another factor used for the selection criterion. Roughness

information has been obtained from process universe of CES selector for alternative

material manufacturing methods such as compression moulding, SMC, transverse

moulding and injection moulding (Figure 4.15). Roughness is a measure of the

texture of a surface. It is quantified by the vertical deviations of a real surface from

its ideal form. If these deviations are large, the surface is rough; if they are small, the

surface is smooth. Manufacturing method affects the roughness range on the

composite materials. Expectation roughness differences are between 0.05 µm and 0.3

µm as shown in Figure 4.16.


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Figure 4.14. Pre-processes on Section thickness vs. shape class (CES, 2005)

Roughness on every part surface has two important aspects that must be

defined and controlled. The first concerns the geometric irregularities and the second

concerns the metallurgical alterations of the surface and surface layer. Roughness

effects labor time in the lead-time of the parts. Parts that have bad surface quality are

exposed to second applications that include repair after painting operations. For this

reason, raw material amounts increase because of forming arrangements on part.

Type and orientation of the fiber affects the roughness. Generally, in composite

production method, woven fabrics are not used as the first layer of the part under the

gel coat due to the leveling problem on the surface of the part. Closed moulding

applications as determined by graph stage are suitable to decrease the roughness

problem on the surface. Open mould applications can cause the roughness problem

on the surface because of less degree pressure effect on the mould are not happened.

Roughness can be seen on flat surface more than curved surface.

Finally, all of criteria have been evaluated to select the best alternative

materials and manufacturing methods. GFRP, CFRP, Fiber Reinforced Aluminum

composites have been found alternative materials while SMC, Compression

Moulding, RTM, Cold Pres Moulding and RIM have been taken as alternative


79

manufacturing methods by using CES selector’s assistant stages of limit and graph

stages.

Figure 4.15. Roughness values of alternative manufacturing methods (CES, 2005)

Figure 4.16. Pre-selected manufacturing methods by roughness


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4.1.1.3. Test Results for Exterior Trimming Parts

In this work, different testing methods have been used to evaluate the

properties of selected materials. The test results were compared with the spec values.

Spec values were taken from different types of automotive component brochures and

technical sources. This type of test and their results are used for determining the

different properties of the selected materials and their results are given in the

following paragraphs.

Three point bending test specimens have been manufactured by hand lay-up

and RTM processes under the same condition with the finished product. Test results

for each specimen and their average values are given in Table 4.6. Stress-strain

curves plotted according to test results for each specimen produced by hand lay-up

and RTM are shown in Figure 4.17 and Figure 4.18 respectively.

Table 4.6. Three point bending test results and averages for hand lay-up and RTM Process Resins B1 B2 B3 B4 B5 Average(Mpa)

Hand lay up Polipol 344 TA 205.9 206.1 244.2 192.8 204.8 210.8 RTM Polipol 336 288.9 331.3 275.4 274.8 282.2 290.5

Figure 4.17. Stress-strain curves plotted by means of hand lay up specimen for three-point bending test


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Figure 4.18. Stress-strain curves plotted by means of RTM specimens for three-point bending test

The minimum requirement from the bending test should be 200 MPa to

satisfy necessary strength value needed in automotive applications. Average values

obtained specimens were higher than minimum requirement. Average values for

hand lay-up and RTM processes are 210.8 MPa and 290.5 MPa respectively. These

differences are due to different manufacturing methods used. Test results showed

that the closed mould applications generally have high average values than the open

mould applications. Different resins are used in applications. It has been seen that the

type of resin does not affect mechanical properties of the part because of some of the

properties have binds the fibers, distributes the stress, protects the fibers from

damages and prevent the brittle crack propagation fiber to fiber. Mechanical

properties generally depend on type of fibers. Non-woven chopped rowing fibers

were used for open mould while woven fibers were used for closed moulding.

Heat Deflection Temperature Test results are shown in Table 4.7. The heat

deflection temperature test results are useful measure of relative service temperature

for a polymer when used in load-bearing parts. Thermal simulations of a system

show temperatures that are encountered by a specific component of that system.

Knowing what temperature that a specific component will have to endure during use

will allow the determination of the best material for that application. Total six

samples have been used for HDT. Three of them were used to test RTM parts while


82

others were used to test hand lay-up parts. HDT properties depend on the properties

and behaviour the results obtained from different manufacturing methods were close

to each other due to the same resin density. Fibers causes improvement in the

mechanical properties, but their effect on HDT result is found negligible.

Table 4.7. HDT test results and average values for the samples produced by hand lay-up and RTM processes

Process Resins HDT1 HDT2 HDT3 Average(°C) Hand lay up Poliya 344 TA 100.7 99.5 102.7 100.9

RTM Polipol 336 90,0 93.6 91,0 91.5

Average values for Barcol Hardness Test is 54.03 Barcol for hand lay-up

samples while it is 61 for RTM specimens. Deviation on measurements is 6.7 for

hand lay-up specimens while it is 4.6 for RTM samples. Closed mould applications

are resulted higher hardness values than open mould applications. Hardness covers

several properties: resistance to deformation, resistance to friction and abrasion.

There are well-known correlations between hardness with tensile strength, and

between resistance to deformation and modulus of elasticity. The frictional resistance

may be divided in two equally important parts: the chemical affinity of materials in

contact, and the hardness itself. A correlation may be established between hardness

and some other material property such as tensile strength. Then the other property

(such as strength) may be estimated based on hardness test results, which are much

simpler to obtain. On the other hand, gel coat thickness on the outside surface of the

part could be found by hardness test and its results affect the surface quality of the

part after heating in furnace for the painting shop. The results of the two tests are

close to each other because of the same behaviour gel coat and putty used on the

surface.

Tension Test results are shown in Table 4.8. Tension test is a mechanical test

method and affects the materials strength values. Strength values depend on the so

many parameters such as material shape, material thickness, materials used, and

manufacturing methods. By pulling on something, you will very quickly determine

how the material will react to forces being applied in tension. As the material is


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being pulled, you will find its strength along with how much it will elongate. Three

samples are used for tension test manufactured by hand lay-up and three samples

manufactured by RTM. Tension test results are strongly depend on the fibers used.

Result values were determined different values because of fiber orientation and fiber

types differences.

Table 4.8. Tension test results for hand lay-up and RTM samples Process Resins T1 T2 T3 Average(Mpa)

Hand lay up Poliya 344 TA 121.7 117.2 104.5 114.5 RTM Poliya 336 135.4 125.4 136.2 132.3

Burn off test was performed to determine the volume fractions of constituents

in a glass fiber reinforced unsaturated polyester composite. Burn off test results are

given in Table 4.9. The weight and volume fractions of glass fibers and polyester

resin have been calculated. Burn off test resulted different values because of different

fibers and resins used in each process. Fibers that replace the mould soak the resin

inside. After the curing its weight is increased from soaking. For this reason, fiber

and resin amounts can be changed according to manufacturing process. The required

between 30 and 35 % per weight for hand lay up while should be between 35 and 40

% per weight for RTM. Test results showed that the selected materials for fender and

bumper are satisfactory for the expectations.

Table 4.9. Burn off results for hand lay-up and RTM samples

Process No Weight of

Resin Burned (g)

Total Material (g)

Fiber Remained (g)

Fiber per Weight (%)

Fiber per Volume

(%)

Han

d La

y-up

W1 2.3 3.5 1.2 0.34 0.18 W2 2.3 3.5 1.2 0.34 0.18 W3 2.2 3.4 1.2 0.35 0.19

RTM

W1 2.2 3.3 1.1 0.40 0.18 W2 2.2 3.3 1.1 0.41 0.18 W3 2.2 3.4 1.2 0.41 0.19


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4.1.2. Material and Process Selection for Interior Trimming Parts

Interior trimming parts have different kinds of constraints compared to

exterior trimming parts. These parts are not directly exposed to environment effects

in the vehicle. Therefore, many material constraints are not used for exterior

trimming parts considered for the material selection. Instead of them, new constraints

given in Table 4.10 have been added for the selection of the best materials for

interior trimming parts. Design requirements have been defined by means of tests

used for interior trimming parts and enough conditions have been added to

constraints. Headlining is chosen as an interior trimming part in vehicle. Because

part is so big, carries so many components on it like flap, signboards and there are air

channels in the headlining for air conditioning system. Headlining can be deformed

easily due to its large size. It can be made overhang unstable on replaced the vehicle

because of carried components. It is always exposed to the hot and cold weather

condition because of air conditioning system pipes mounted on it. For these reasons,

the best alternative materials and manufacturing method must be determined to be

support the applied loads on it and to resist the weather conditions. Some of the tests

such as burning behaviour test, melting test, thermal shock test, etc have been made

to define the best material and manufacturing method and to evaluate the results for

the selected materials. The test results determined for interior trimming materials

were defined as constraints for headlining in the design requirements. Because of the

test results were not given the arithmetic values, they were not added to design

requirements as shown in Table 4.10.

Alternative materials are shown in Table 4.11. Alternative materials have

been determined from automotive industry and technical brochure. These materials

can be used as internal materials for interior trimming parts. Nevertheless, this is not

a professional way to select alternative materials for automotive industry. For this

reason, the best alternative materials with the aid of the material selection technique,

CES selector, were determined to eliminate or to accept previous selection materials

without CES selector. Material selection in Ashby’ method was started with design

requirements and continued with material indices. Material indices are still interest in


85

weight reduction and lightweight materials. A material index has been calculated for

headlining as two.

Table 4.10. Design requirements of Headlining FUNCTION Headlining OBJECTIVE Lightweight materials to be satisfied the constraints

CONSTRAINTS

§ Burning Behaviour Test § Melting Test § UV Resistance Test § Heat Cycle Test § Thermal Shock Test § Heat Aging Test § Chemical Resistance Test § Wear Resistance Test § Impact Resistance Test § Tensile Test § Vicat Softening Test

Free variables § Material

Table 4.11. Properties of alternative materials for Headlining MATERIAL CFRP GFRP PP PVC ABS PU

Density (g/cm³) 1800 1550 900 1500 1180 1200 Young Modulus (Gpa) 230 80 0.99 1.5 2.3 0.025

Cost (Euro/kg) 45 9 0.95 2.6 2.7 4.2 Elongation at break (%) 1.8 3 90 50 30 500 Tensile strength (MPa) 3530 2400 45 60 48 30

4.1.2.1.CES Selector on Limit Stage for Interior Trimming Parts

Alternative material selections of CES selector have been performed by

Select section of CES 4.5. First, Limit Stage has been used to describe alternative

materials. In the limit stage, so many material properties as arithmetic values were

used. Arithmetic values show the intervals as minimum and maximum. The intervals

were obtained from CES selector’s material universe. After material properties such

as density between 890 and 1580 kg/m³ and cost between 0.93 and 72.37 Euro/kg

were entered into CES, CES selector showed 443 materials as candidates for interior

trimming parts among 2882 materials as shown in Figure 4.19.


86

Figure 4.19. Limit stage for headlining after entered density and cost (CES, 2005)

Some of other properties related with composition (polymer properties

selected) and mechanical properties such as young’ modulus, bulk modulus,

elongation etc., as shown in Table 4.12, have been used to optimize and reduce the

numbers of alternative materials. After these operations, they have been reduced

from 443 to 40 as shown in Figure 4.20.

Table 4.12. Mechanical properties used for interior parts in limit stage

Mechanical Properties Unit Min. Value Max. Value Young' Modulus Gpa 1,31 550 Shear Modulus Gpa 0,32 60 Bulk Modulus Gpa 2,9 80 Poisson's Ratio 0,305 0,426 Hardness as Vickers Gpa 0,006 0,157 Elastic Limit Gpa 0,012 0,055 Tensile Strength Gpa 0,03 1,05 Compressive Strength Gpa 0,025 0,84 Elongation % 0,32 550 Fracture Toughness Gpa.m½ 0,0015 0,023 Loss Coefficient 0,012 0,044 Modulus of Rupture Gpa 0,003 0,012 Shape Factor 4,4 5,9


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Finally, material selection table in CES showed 8 results as ABS, PVC,

ASA, PMMA, SAN and their functions when all of important criteria have been

added to gaps related to material properties such as thermal properties that include

glass temperature values between -25 and 179°C and thermal expansion values

between 1.17e8 and 1.8e8 strain/°C; optical properties that include transparency such

as transparent, opaque and translucent and also durability that includes flammability

resistance, acid resistance, alkali resistance, etc., shown in Figure 4.21 for thermal

and optical properties; Figure 4.22 for durability; Figure 4.23 for other durability

values and have been added to Appendix to show them clearly. The pre-selected

materials were found in thermoplastic material groups without reinforced. ABS has

lower cost as material when the other alternative materials are compared and so

many interior components except headlining such as pillar covers, some parts of

front console, garnish, and so on can be manufactured from ABS. Furthermore, ABS

and PVC produce in different companies as raw materials in Turkey. It provides the

reducing of the materials cost and this is another reason to be selected among the best

alternative materials. ABS has perhaps the best balance of properties when cost is a

factor. It has good chemical and stress-resistance as well as a combination of

toughness with rigidity and creep resistance. The strength of ABS depends on

temperature. As temperature decreases, the impact strength of ABS also decreases.


88

Figure 4.20. Composition and Mechanical properties of Headlining (CES, 2005)

Figure 4.21. Thermal and optical material properties for headlining (CES, 2005)


89

Figure 4.22. Durability results for headlining material selection (CES, 2005)

Figure 4.23. Durability results for candidate materials (CES, 2005)

On the other hand, pre-selected materials affect the material process methods.

According to materials and processes technical information, the best process or

processes will have been chosen from 136 different processes by means of the limit


90

stage on CES. After physical attributes obtained from process universe that include

mass ranges between 0.003 and 6000 kg, section thicknesses between 2,5 and 10

mm, roughness between 0.1 and 3.2 µm and quality factor between 1 and 10 have

been added to the limit stage related to headlining material processes, remained

alternative processes were reduced to 55 as shown in Figure 4.24. After adding

economic attributes to stage, the numbers of alternative remain processes reduced to

50 as those are shown in Figure 4.25.

Figure 4.24. Physical attributes shown on limit stage (CES, 2005)

When other manufacturing properties required that include minimum and

maximum values such as economic attributes as economic batch sizes (units), cost

modeling as capital cost and tooling cost, shape as dished sheet and process

characteristics as primary and discrete have been added to the limit stage of CES

selector, in the final step of pre-selection of processes, twelve alternative

manufacturing processes and four of them related to composite materials have been

remained to evaluate for headlining and related to composite materials such as SMC,

hand lay-up, thermoforming, vacuum pressure bag, etc., as shown in Figure 4.26.


91

Figure 4.25. Economic attributes for headlining process selection (CES, 2005)

Figure 4.26. The values of cost modelling, process characteristic, and shape factor (CES, 2005)

SMC plays an important role as a manufacturing method for exterior

trimming parts, but within some of special interior using area, it can be used as an


92

alternative manufacturing method, for instance, airplane industry. In plane, owing to

expose high pressure, generally materials selected are produced by SMC. Hand lay

up is known as common manufacturing method for thermoset materials in bus

industry because of low investment cost, fast prototyping, and moulding cost is lower

than others are. A simplistic overview of the single-sheet thermoforming process

consists of heating an extruded sheet of plastic and either forming the sheet over a

male mold or into a female mold. Thermoforming is an alternative method to

produce the thermoplastic materials such as ABS, PVC, etc. There are a few

considerations when choosing vacuum forming. The process does not support

variable wall thicknesses, and the part’s geometry must allow a straight pull (no

undercuts or side action). Additionally, vacuum forming cannot manufacture

strengthening ribs or mounting bosses. For large production runs, vacuum forming

tools are machined from aluminum. However, the low pressure and temperature of

the forming operation facilitates the use of tooling constructed from many materials,

including ABS, polycarbonate (PC) and polyphenolsulfone (PPSF/PPSU). The

prototypes of the forming operation facilities the use of the tooling constructed for

the high pressure and temperature from many materials wood; especially plywood,

carbon or stainless steel. Thermoforming is the best alternative manufacturing

method for ABS because of low cost, forming middle complex shapes and easy

moulding material selection. Vacuum pressure bag is generally used with thermoset

materials in boot, yacht industry.

4.1.2.2.CES Selector on Graph Stage for Interior Trimming Parts

Headlining material selection by means of graph stage has been started with

2882 different materials as shown in Figure 4.27. These materials first have been

evaluated in Density vs. Young’s modulus. Minimum values of Density and Young’s

modulus, 890 kg/m³ and 1.31 GPa respectively, and the slope of material indices

have been added to optimize the results (Figure 4.28).


93

Figure 4.27. Alternative materials on density vs. young’ modulus for headlining (CES, 2005)

Figure 4.28. Exact area for alternative materials on young’s modulus vs. density


94

Finally, 53 alternative materials have been remained to be selected (Figure

4.29). These are ABS, PMMA, PU, ASA, and SAN and so on. Approximately the

same materials have been found in pre-selected materials on the graph stage too. This

was a proof showing on the good way. In addition to materials determined on the

graph stage, PU shows itself as a new alternative material. As we know that two

materials are alternative to each other on the automotive industry, ABS and PU. ABS

fills the gaps of the PU for interior trimming parts on the bus industry and vice versa,

it can be acceptable. Polyurethane offers a very wide range in which items can be

produced. They range from 10 Shore to over 80 Shore D. Polyurethane when at their

highest hardness levels, have significantly better impact resistance than almost all

plastics. Such great toughness, combined with the many other outstanding properties

associated with the high hardness polyurethane, leads to many applications in

engineering. Polyurethane is characterized by high elongation, high tensile strength,

and high modulus. This provides a combination of toughness and durability in

fabricated parts. Many Polyurethane Elastomers remain flexible at very low

temperatures and possess outstanding resistance to thermal shock. The low

temperature resistance of Polyurethane has lead to many applications in below 0 °C

conditions. During the initial moulding process and under controlled conditions,

Polyurethane can be bonded to a wide variety of materials. High strength bonds can

be obtained on most metals, wood and many plastics. This bond strength usually

exceeds the bond of rubber to metal substrate by several times. Many rubbers and

plastics have excellent resistance to one or more specific solvents, oil, or chemicals,

for example, polyurethane based adhesives and sealant.

Another evaluation criteria used for the selection of the best alternative

materials is the physical properties of the material. This is the elongation vs. shape

factor. 2882 alternative materials have been used to evaluate and finalize the best

material as shown in Figure 4.30. 163 materials have been obtained for the

evaluation as shown in Figure 4.31. This total number includes 53 materials, which is

evaluated in previous section.

Both of the graph stages have already found the same 53 materials for the

evaluation. For this reason, 53 materials are selected before checked. When


95

unsatisfied materials such as oak, balsa, and epoxy resin and so on within the list of

the pre-selected materials were removed from alternative materials, finally 10 pre-

selected materials stayed to be chosen such as ASA, ABS, EVOH, PA, PC, PU, PP,

PMMA, SAN, and PEEK. The ASA family of resins is a durable, thermally stable,

chemically resistant, and colorfast thermoplastic suitable for demanding, long-term

outdoor use. Generally, ASA uses the outdoor applications in automotive industry,

especially in OEM’s groups. For this reason, it has high cost when we compare with

the interior trimming materials.

In general, the combination of lightweight, high strength, and low processing

costs make thermoplastics such as ABS, PU, PP, etc well suited to many applications

for interior trimming parts in bus industry. The weight and cost values of headlining,

shown in Figure 4.32, were calculated by Catia V5 R19 as given in Table 4.13. The

most common methods of processing thermoplastics are injection molding,

extrusion, and thermoforming.

Figure 4.29. Alternative materials for interior trimming (CES, 2005)


96

Figure 4.30. Alternative materials for headlining on shape factor vs. elongation

Figure 4.31. Pre-selected materials on shape factor vs. elongation (CES, 2005)


97

Figure 4.32. Headlining’3D drawings as front and rear drawn by Catia Table 4.13. The weight and cost values for headlining with alternative materials

(Catia V5 R19) MATERIAL DENSITY

kg/m³ COST Euro/kg

HEADLINING kg

HEADLINING VOLUME m³

TOTAL COST Euro/kg

GFRP 1550 9 5.7

0.0036

51.3 CFRP 1800 45 6.6 297.0 ABS 1180 2.7 4.3 11.6 PP 900 0.95 3.3 3.1 PU 1200 4.2 4.4 18.5

PVC 1500 2.6 5.5 14.3

4.1.2.3. Test Results for Interior Trimming Parts

Burning behaviour, melting, heat cycle, thermal shock, heat aging, UV

resistance, chemical resistance, abrasion resistance, drop impact, tension and vicat


98

softening tests have been performed to check suitability of material; ABS, for

internal part. The results of the tests of headlining are shown in Table 4.14.

Test results are valid only to the specimens of the product in the form in

which they were tested. Small differences in the composition or thickness of the

product may significantly affect the performance during the test and may therefore

invalidate the test results. Care should be taken to ensure that any product, which is

supplied or used, is fully represented by the specimens, which were tested. In tests,

specimen thickness used was determined as the dimension of 3± 0.2 mm and

composition was checked with the aid of test.

Burning behaviour test has been done for determining the burning behaviour

of materials used in the interior component of certain categories of motor vehicles,

and is intended to ensure that they meet fire safety standards. Burning behaviour test

results have been found as satisfactory to use as interior trimming material because

of the burning rate of 46 mm/min. Other materials such as ASA, PP, PU etc.

determined by materials selection method, CES selector, should be performed

satisfactory result to use as automotive interior trimming material.

Melting behaviour test has been performed according to the same directive

with burning behaviour test used for automotive part too. Cotton was not burned

during the test with the aid of the melting ABS. Then the result of the test can be

acceptable.

The result of the chemical resistance test has been controlled according to

required spec value and has been found in satisfactory to use as automotive trimming

part. On the other hand, ABS contains no heavy metal stabilizers such as lead that is

often used in the processing of other thermoplastics; hence, it is safe for carrying

potable water. For many years has been used to carry distilled water for medical use

and renal dialysis fluid. It is considered to be taint free, this makes it very suitable for

packaging food and beverages. ABS is slow burning, but gives off carbon monoxide,

carbon dioxide, and nitrous oxides. Inhaled vapor may be harmful. Dust from

grinding etc can cause irritation to the skin and eyes and is an explosion hazard.

Heat cycle test has been made with three specimens and in the same results

are obtained. All of the specimen’s results have been found in satisfactory. If any


99

differences have been faced on the specimens, alternative tests would have been

needed to perform for a good result. Test results that relate to heat cycle were in good

agreement with directives. No visible distortion, deformation, discolors, tears, cracks,

peeling off, etc. have been observed on test results.

Thermal shock test have been performed to evaluate the behaviour of the

material under the different temperatures, which is, living short-term temperature

difference at the state, for example, desert.

Abrasion on parts is a physical property and this has been simulated on

materials specified by means of abrasion tester. No laboratory abrasion test can

guarantee success in the field. Unfortunately, there are just too many influences to be

modeled in the lab. As a result, the tests that were performed may not accurately

identify potential problems. The ideal solution is to analyze the product in actual use

under the actual intended use conditions. Unfortunately, it often takes many years

before useful data becomes available. Additionally, the cost of conducting a field test

could be prohibitive and the complexity of identifying the influences can be

unwieldy. Laboratory testing provided a uniform way to measure resistance to

abrasion, allowing material tested in the same manner to be compared with CES

selector results. While a lab test may not represent the actual conditions materials are

exposed to, they can duplicate many real world conditions allowing you to have

higher reproducibility with your evaluations. In addition, there was greater flexibility

with the methodology, it was less expensive than field-testing, and you can test more

samples.

The UV resistance test has been made with ABS material. After the test,

visible color changing and fading were not observed on material. The UV resistance

of plastics involves a number of factors that can affect in material choice such as

thickness, opacity, and the use of stabilizers. These three factors are combined to

defend plastics against ultraviolet (UV) light. Light degrades plastics by transferring

its energy into the plastic. This energy can cause damage by creating heat, or this

energy can actually break molecular bonds in a plastic’s structure. Both the heat and

the breaking of bonds can create a loss of physical properties in the plastic. The

higher energy of the UV rays causes almost all UV damage in plastics. Regular


100

visible light causes almost no degradation even over many years of exposure. Plastics

in opaque color are plastics that “light” do not pass through. In an opaque plastic, the

light has to break down the outer layer before it can break down the inner section of

the plastic. The inner layer of plastic can retain its strength much longer the more

opaque the plastic. If a plastic is completely black (or some other opaque color, or

close to opaque color like RAL 7016) then the light only acts on the surface and

much less damage will occur over time. Each material was tested for UV resistance;

however, each location where automotive industry was installed has a different UV

exposure level. No two locations get exactly the same amount of sunshine, and most

locations do not get the same amount of sunshine from year-to-year. UV resistant test

for ABS performed according to Florida test conditions, the worst, may not be

typical of the service life. This makes it difficult to make general statements about

UV resistance of materials.

Vicat softening temperature test is very important for both quality control and

research on plastics because it determines the heat resistance characteristics of

material, and is fundamental to define precisely the thermal behaviour of the

polymers. The result of the test was found above the temperature level determined as

99.2°C and quality control standard was performed with the result.


101

Table 4.14. Test results for interior trimming material (ABS)

Test Test Method Required Spec Value Test Result Burning Behaviour Test 95/28/EC Burning rate,max,100 mm/min 46 mm/min

Melting Test 95/28/EC Cotton not flame No burning

Heat Cycle Test ES-X60210

No visible distortion, deformation, discolor, tears, cracks, peeling off, tack and

so on

No changing

Thermal Shock Test ES-X83215


so on

No changing

Hear Aging Test ES-X60120


so on

No changing

UV Resistance Test ES-X60121 No visible discolor and fading No changing

Chemical Resistance Test ES-X60120


so on

No changing

Abrasion Resistance Test ES-X60120 3 or more 5

Drop Impact Test ASTM 2444-4

No such defects as breaks, tears and deformation to have

considerable effect on appearance

No changing

Tension Test ISO/FDIS 527-1

Tensile force: 32 N/mm²(min) Tensile force: 33 N/mm²

Flexural modulus:1600 N/mm² Flexural modulus:

1522 N/mm²

Vicat Softening Test ISO 306 T min.= 85°C 99.2°C


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5.CONCLUSIONS Murat ÖNŞEN

103

5. CONCLUSIONS

In this study, Ashby’s material selection method has been employed to select

the best materials for exterior and interior trimming parts used in vehicles.

Mechanical, physical, optical, thermal and durability properties have been used as

control factors for material selection criteria. It has been shown that CES selector

provides an efficient methodology for material selection of automotive parts. This

study showed that fender, bumper, and headlining can be improved significantly with

polymer based composite materials used and the following conclusions can be

derived from this work.

1. First of all, alternative material selection process for exterior trimming

parts was done by limit stage on CES selector. Limit stage results showed that pre-

selected materials such as glass fiber reinforced plastics and carbon fiber reinforced

plastic could be used for exterior trimming parts. Secondly, both of alternative

materials have been evaluated in graph stage on CES selector. In graph stage, 150

alternative materials have been determined by means of material index, working area

between minimum and maximum limits of material properties including mechanical,

physical, and so on. 150 materials have been found so much to be evaluated as

alternative materials, so many unusable sub-materials that include resins; epoxy,

polyester; wood, oak, plywood; stone, etc. have been removed from these list. In the

final stage, alternative materials have been obtained after filtration such as GFRP,

CFRP, and fiber reinforced aluminum composites.

2. According to pre-selected materials, alternative manufacturing method

selection processes were evaluated with the aid of these results. Decisions were done

by CES selector. The optimum process were determined with the aid of assistant

criterions such as section thickness, mass range, roughness, economic batch size

(units), material class, shape. Respectively all of the paired constraints such as mass

range vs. material class, section thickness vs. shape class, and roughness vs. primary

were drawn on CES selector and determined alternative processes. In conclusion, the

best alternative manufacturing methods have been found as SMC, RTM,


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compression moulding, injection moulding and hand lay-up for the production of

exterior trimming parts such as fender and bumper.

3. Before the operations such as material and process selection for exterior

trimming parts, alternative materials had been determined such as GFRP, CFRP,

stainless steel, aluminum, high and mild carbon steels because of these materials are

still used in automotive industry. Some of the materials such as glass fibre

composites have been tested for mechanical, physical properties. These results

obtained from the tests are then used as constraints in evaluation stage as design

requirements in this study. Candidate materials found in the final step of the CES

selector except the glass fibre reinforced plastics could be used as alternative

materials for exterior trimming parts and tests have been done. Tension, bending,

heat deflection, barcol hardness, burn off tests could be done for these materials in

order to confirm their suitability.

4. Interior trimming parts, specifically headlining, were evaluated in this

study. On the limit stage of the interior trimming part, eight alternative materials

such as ABS, PVC, ASA, PMMA and the derivative of these materials such as ABS

with heat resistance, ASA with reinforced as PVC were obtained by CES selector.

These alternative materials were compared by using the results of the graph stage. At

the result of the graph stage by means of some assistant sketches such as density vs.

Young’ modulus and shape factor vs. elongation, 53 alternative materials were

obtained. Some of the alternative materials are acrylonitrile butadiene styrene (ABS),

acrylonitrile styrene acrylate (ASA), nylon (PA), ethylene Vinyl Alcohol (EVOH),

polypropylene (PP), polyurethane (PU), polymethyl methacrylate (PMMA) as main

material and ABS reinforced with stainless steel fibres, ASA reinforce with PC, etc.

When both of the stages are combined, main alternative materials are determined as

ABS, ASA, PU, PMMA, PP, PVC, EVOH, and PA.

5. Alternative processes compatible with these materials and required

properties were determined. Alternative materials were determined by CES selector.

First, the limit stage was used to determine alternative processes. As a result of the

limit stage, some of alternative materials have been determined as sheet molding

compound; hand lay up, thermoforming, vacuum pressure bag, spray up, and


105

autoclave forming related to composite materials. These results were checked by

graph stage on CES selector. Manufacturing method such hand lay up,

thermoforming for composite materials and deep drawing, explosive forming for

other engineering materials have been found from graph stage of CES selector.

6. Before determining alternative material for interior trimming parts, some

of the requirements needed for alternative materials in automotive industry have been

tabulated. Then, CFRP, GFRP, PP, PVC, ABS, and PU are selected as candidate

materials for evaluation. Test results have been used to check the suitability of these

alternative materials for automotive components. It has been shown that they can be

used as alternative materials for automotive industry.

7. The weight and cost values for fender and bumper were calculated. GFRP

and CFRP selected as alternative for exterior trimming materials have been used to

compare cost and weight values. CFRP and GFRP’ weights for bumper were

calculated as 7 kg and 6.1 kg respectively while CFRP and GFRP’ cost were

calculated as 315 and 54.9 Euro/kg respectively. In the same way, the weight of

fender was calculated for CFRP and GFRP as 3.6 and 3.1 kg respectively while the

cost of fender was found for CFRP and GFRP as 162 and 27.9 Euro/kg respectively.

8. The weight and cost values for exterior trimming parts, fender and

bumper, were calculated for mild carbon steel, stainless steel and aluminum alloy

evaluated as alternative materials. The weight of mild carbon steel was found as 30.5

kg while the cost was determined as 12.2 Euro/kg. The cost of stainless steel was

found as 123.6 Euro/kg while the weight of stainless steel was calculated as 30.9 kg.

Finally, the weight of aluminum alloy was determined as 10.6 kg while the cost of

aluminum alloy was found as 13.8 Euro/kg.

9. Alternative interior materials have been used to calculate the weight and

cost values of headlining. The weights of alternative materials such as CFRP, GFRP,

ABS, PU, PVC were found as 6.6, 5.7, 4.3, 4.4, 5.5 kg respectively while the cost of

them were calculated as 297, 51.3, 11.6, 18.5, 14.3 Euro/kg respectively.


106

107

REFERENCES

ACMA, 2004, American Composites Manufacturers Association.

ANDREA, D.J., BROWN, W.R., 1993. Material Selection Processes in Automotive

Industry, Michigan Transportation Research Institute, USA, p34.

ANDERSON, B.J., COLTON, J.S., 1989. A study in the lay-up and consolidation of

high performance thermoplastic composites, Sampe Journal, 25(5):22-28.

ASHBY, M.F., CEBON, D, 1992. ‘Computer–based materials selection for

mechanical design’ in ‘Computerization and networking of materials

databases’, ASTM STP 1140, American Society for Testing and Materials,

Philadelphia.

ASHBY, M.F., CEBON, D., 1993. Material Selection in Mechanical Design,

Troisieme Conference Europeenne sur les Materiaux et les Procedes Avances

Euromat ‘93, Paris.

ASHBY, M. SHERCLIFF, H., CEBON, D. 2007. Materials Engineering, Science,

Processing and Design, University of Cambridge, UK.

BEYER M., JAMBOR, A., 1993. New Cars-New Materials. ASME J Eng Mater

Technology, 115:391–7, Mater Des 1997; 18:203–9.

CALLISTER, W.D., 2000. Materials Science and Engineering Materials: An

Introduction, John Wiley & Sons, New York, Fifth Edition.

CAMELYAF, 2009. Camelyaf San. ve Tic. A.Ş.

CHANG, T., WYSK, R.A., WANG, H., 1998. Computer-Aided Manufacturing,

Prentice Hall Sec., p596-598.

CRIPPS, D., 2001. FRP Composite Processing, Gurit, p1-5

CROSS N., 1994. Engineering Design Methods and Strategies for Product Design,

second eds. John Wiley & Sons, Chichester, p33-47.

CUI, X., WANG, S., HU, S.J., 2008. A method for optimal design of automotive

body assembly using multi-material construction, Materials and Design 29:81–

387.

108

DAVOODI, M.M., 2008. Conceptual design of a polymer composite Automotive

bumper energy absorber, University Putra Malaysia, 43400 UPM Serdang,

Selangor, Malaysia, Elsevier Materials and Design 29:1447–1452.

DORSETT, N., 2004. Guide to composites (SP), GTC-1-098-51.

EEC/95/28, 2007. The European Parliament and of the Council, InterRegs Ltd, p40

ENRICO, M., CARRUTHERS, J., GIUSEPPE P., 2007. The future use of structural

composite materials in the automotive industry, international journal of vehicle

design, 44(3/4):211 – 232.

ERMOLAEVA, N.A., CASTRO, M.B.G., KANDACHAR, P.V., 2004. Materials

selection for an automotive structure by integrating structural optimization

with environmental impact assessment, Delft University of Technology,

Elsevier Materials and Design 25:689–698.

FARAG, M.M., 1997. Quantitative methods of materials substitution: Application to

automotive components, Materials and Design 29:374–380

FARELY, G.L., 1983. Energy Absorption of Composite Materials, Journal of

Composite Materials, 17:267-279.

FERRANTE, M., SANTOS, S.F., DE CASTRO, C.F.R., 2000. Materials Selection

as an interdisciplinary technical activity: basic methodology and case studies,

Materials Research, 3(2):1-9.

FREDERICK, C.D., 2000. Rotational Molding. Plastics Solutions International,

Rotoworld magazine, p56.

FISHER, K, 1997. Resin flow control is the key to RTM success, High Performance

Composites, Ray Publishing, p34.

GAY, D., 2002. Composite Materials Design and Applications ISBN 1-58716-084-6

(alk. paper) 1, Composite materials. I. Title. TA418.9.C6 G39.

GJOSTEN, N.A., 1995. The next generation of vehicles - a materials challenge,

American Institute of Physics Corporate meeting, October 1995, p1.

GURIT, 2001. Guide to Composite, Gurit press, UK.

HERBERT, F., 2003. Handbook; Composite Materials “AKZO, GH Paderborn” p14.

109

HONNAGANGAIAH, K.N., 2001. Design and evaluation of composite car-front

sub-frame rails in a sedan and its corresponding occupant crash injury

response. Bachelor of Engineering, Bangalore University, India, p16-17.

HOSSEINZADEH, R., SHOKRIEH, M.M., LESSARD, L.B., 2004. Parametric

study of automotive composite bumper beams subjected to low-velocity

impacts, Composite Structures 68:419–427.

INES, R., PEÇAS, P., HENRIQUES, E., 2008. The Need for a Life Cycle Approach

on the Material Selection: a Case Study of an Automobile Fender, Proceedings

of the World Congress on Engineering Vol II WCE , London, U.K.

INES, R., PEÇAS, P., HENRIQUES, E., SILVO, A., 2008. Life cycle engineering

methodology applied to material selection, a fender case study, Elsevier

Journal of Cleaner Production 16:1887-1899.

ISO 2580-2, 2007. Plastics, Acrylonitrile-butadiene-styrene (ABS) moulding and

extrusion materials, Part 2: Preparation of test specimens and determination of

properties.

KUO, T.C., 2001. Design for manufacture and design for “X”: concepts,

applications, and perspectives, Computer& Industrial Engineering, 41:241-260

MAMALIS, A.G., ROBINSON, M., CARRUTHERS, J., 1997. “The energy

absorption properties of composite materials: A literature survey”. Composite

Structures, 37:109-134.

MARQUARDT, T., 2006. Vacuum Infusion Process technology

MATOLCSY, M., 2004. Scientific Society of Mechanical Engineers (GTE), General

survey of bus frontal collisions: is regulation needed, Proc. Budapest, Hungary

Instn Mech. Engrs, 218 Part D: J. Automobile Engineering.

MAZUMDAR, S.K., 2002. Composites manufacturing; materials, product, and

process engineering. Technology and Engineering, CRC Press, USA, p392

NGUYEN, Q.M., ELDER J.D., BAYANDOR, J., THOMSON, S.R., SCOTT, L.M.,

1999. ”A review of explicit finite software for composite impact analysis”.

Journal of Composite Materials, 39: 375-386.

110

PING, C.G.E., WANG, N., STEPHEN, C., LU, Y., 2002. An Evolutionary Modeling

Approach for Automotive Bumper System Design and Analysis, Journal of

Computing and Information Science in Engineering, 2:141

RAMAKRISHNA, S., HAMADA, H., 1998. Energy Absorption Characteristics of

Crashworthy Structural Composite Materials. Eng. Mat., 141-143:585-620.

SAE J 1685, Classification System for Automotive Acrylonitrile-Butadiene-Styrene

(ABS) and ABS + Polycarbonate Blends (ABS+PC) Based Plastics

SAPUAN, S.M., MALEQUE, M.A., HAMEEDULLAH, M., SUDDIN, M.N,

ISMAIL, N., 2004, A note on the conceptual design of polymeric composite

automotive bumper system Journal of Materials Processing Technology, 159:

145–151

SAPUAN, S.M., 1999. A Computer-Aided Material Selection for Design of

Automotive Safety Critical Components with Novel Materials.

SEDDON, D. & Associates, 2003. ABS Technical Data and Information Sheet, ECN

News “Product Profile”, Europe

SEHANOBISH, K., 2009. A Vision for Carbon Fiber Composites (CFC) in

Automotive, the Dow Chemical Company brochure.

SHANION, O. S., 2006. A material selection model based on the concept of multiple

attribute decision-making. Materials and Design, 27:329–337.

SHIN, K.C., LEE J.J., 2002, Axial crush and bending collapse of an

aluminum/GFRP hybrid square tube and its energy absorption capability.

Elsevier Science, 57(1-4):279-287

SP, 2001. GURIT Composite technology, guide to Composite, p56.

SPI, 1991. SMC Design Manual from SMC Automotive Alliance of the Society of

the Plastics Industry’s, Composites Institute.

SUDDIN, M.N., SALIT, M.S., ISMAIL, N., MALEQUE, M.A., ZAINUDDIN, S.,

2004. Total design of polymer composite Automotive Bumper fascia.

Suranaree J. Sci. Technol. 12(1):39-45

SUJIT D., 2001. The cost of automotive polymer composites: A review, and

assessment of the DOE’s lightweight materials composites research. U.S.

Department of energy under contract, p7-15.

111

THORNTON, P.H., 1979.“Energy Absorption in Composite Structures”, Journal of

Composite Materials, Vol. 13, pp. 247-262.

TS 1398-1 EN ISO 527-1, 1997. Plastics-Determination of tensile properties-Part 1:

General principles Tension test for plastic materials.

WU L, CARNEY, J.F, 1997. Initial collapse of braced elliptical tubes under lateral

compression. Int J Mech Sci; 39(9):1023–36.

ZHANG, Y., 2006. Lightweight design of automobile component using high strength

steel based on dent resistance, Elsevier Materials and Design, PR China,

27:64–68.

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CURRICULUM VITAE

Murat ÖNŞEN was born in Berlin in Germany, in 15 June 1979. He has started

in educational life firstly in 1984 in Germany by kindergarten, then with primary

school in 1986 in Adana, and gone to secondary school in 1990. He has graduated

from Adana Erkek high school in 1996 in Adana. He has registered Gaziantep

University Mechanical Engineering Department in 2000, and graduated in 2005. He

has not completed in his military service. He has been working in R&D department

of TemsaGlobal Adana factory for five years. He is not yet married and living in

Adana still. He has firstly started his Msc degree in Çukurova University Institute of

Social Sciences Marketing Program and gone for half of year in 2005 and then in

2006 in Çukurova University Mechanical Engineering Department. Msc degree is

related with composite materials and still working in TemsaGlobal Adana Factory as

a project engineer in R&D department.

Some of his hobbies are scuba diving, a professional scuba diver, and

swimmer, reading, listening music and tracking in mountains as a green life friend.

114

APPENDIX-1 Technical properties of Carbon fiber reinforced plastic (CES 2005)

115

APPENDIX-2 Technical properties of glass fiber reinforced plastics (CES 2005)

116

APPENDIX-3 the properties of Age-hardening wrought AL alloys (CES 2005)

117

APPENDIX-4 the properties of Stainless steels (CES 2005)

118

APPENDIX-5 the properties of High Carbon Steel (CES 2005)

119

APPENDIX-6 the properties of Medium Carbon Steel (CES 2005)

120

APPENDIX-7 ABS (Acrylonitrile Butadiene Styrene) (CES, 2005)

121

APPENDIX-8 ABS (Acrylonitrile Butadiene Styrene) (CES, 2005)

122

APPENDIX-9 ASA (Acrylate Styrene Acrylonitrile) (CES, 2005)

123

APPENDIX-10 PP (Polypropylène) (CES, 2005)

124

APPENDIX-11 PP (Polyurethane) (CES, 2005)

125

APPENDIX-12 PVC (Poly Vinyl Chloride) (CES, 2005)

126

APPENDIX-13 Thermoforming properties (CES, 2005)

127

APPENDIX-14 Rotational Moulding properties (CES, 2005)

128

APPENDIX-15 Injection Moulding properties (CES, 2005)

129

APPENDIX-16 RTM Process properties (CES, 2005)

130

APPENDIX-17 Hand Lay-up process properties (CES, 2005)

131

APPENDIX-18 SMC properties (CES, 2005)

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