Faculty of Manufacturing Engineering

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Faculty of Manufacturing Engineering

DEFORMATION OF L-SHAPED AEROSPACE COMPOSITE COMPONENTS

Mohammad Hamdan Bin Mohd. Sanusi

Doctor of Philosophy

2017

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DEFORMATION OF L-SHAPED AEROSPACE COMPOSITE COMPONENTS

MOHAMMAD HAMDAN BIN MOHD. SANUSI

A thesis submitted

in fulfillment of the requirements for the degree of Doctor of Philosophy

Faculty of Manufacturing Engineering

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

2017

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DECLARATION

I declare that this thesis entitle “Deformation of L-Shaped Aerospace Composite Components” is the result of my own research except as cited in the references. The thesis has not been accepted for any degree and is not concurrently submitted in the candidature of any other degree.

Signature : ………

Name : ………

Date : ………

Mohammad Hamdan b. Mohd Sanusi

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APPROVAL

I hereby declare that I have read this thesis and in my opinion this thesis is sufficient in terms of scope and quality for the award of Doctor of Philosophy.

Signature : ….……….

Supervisor Name : ………..

Date : …….……….

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DEDICATION

To my beloved parents, wife and family.

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ABSTRACT

Advanced composite materials are increasingly selected to be used in fabricating new generation of aircraft primary structures than traditional materials due to its high strength- to-weight ratio, fatigue and corrosion resistance. Despite the rapid rising of the composite usage in aircraft industry recently, composite structures depict process-induced geometrical and dimensional distortion after processing. The shape deformation is unpredictable and contributes a mismatch between assembled components. Often, a traditional trial-and-error approach is deployed iteratively to ensure manufacturability in the mass production, which is very uneconomical, expensive and time consuming. There is still lacking experimental data and studies on the effect of different weaving styles of plain weave (PW), 5 harness satin (5HS) and 8 harness satin (8HS) in affecting shape deformation of angled composite laminates. The composite material selected was carbon fibre reinforced with epoxy matrix that could be cured at elevated temperature of 180°C with 7 bars pressure in the autoclave.

Using design of experiment (DOE) methodology, two-level fractional factorials of 2^4-1 Resolution IV were performed to investigate the main effects and interactions of different plies orientation, number of layers, sample sizes, tool materials as well as weaving styles in affecting the spring-in angle of composite laminates. From the design of experiments and analyses of variances, the plies orientation, number of layers, sample sizes and weaving styles were successfully determined to be significant when comparing the effect of PW and 8HS woven fabric. PW fabric induced approximately three times spring-in angle than 8HS.

This relationship was determined to be strong with R-squared value of 97.2% and 87.9%

when the aluminium and carbon tool was kept constant, respectively. Meanwhile, the relationship of PW and 5HS, and 5HS and 8HS were moderate with an average of R- squared values of 66%. There were some level two interaction terms affecting shape deformation mainly between plies orientation and tool materials when the weaving material was kept constant. On the other hand, the majority of level two interaction terms were between plies orientation and number of layers, and plies orientation and sample sizes when the tool materials were kept constant. Using the actual testing results of coefficient of thermal expansion and chemical shrinkage, the analytical data was calculated and compared with the actual measured results. The coefficient of thermal expansion and chemical shrinkage strain at the through-thickness direction is larger by 10 to 18 times than the in-plane properties dependent of the types of weaving pattern. Unfortunately, the analytical results were not in agreement with the experimental data possibly due to fibres misalignment and slippage during the lay-up process as well as non-thermoelastic properties not taken into account. Despite that, the effect of weaving styles cannot be ignored because statistically there were some main effects and interaction terms that might affect the shape deformation of L-shaped composite laminates.

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ABSTRAK

Bahan komposit terkini semakin dipilih untuk digunakan dalam rekabentuk generasi baru struktur utama pesawat kapal terbang di bandingkan dengan bahan-bahan tradisional kerana mempunyai keutuhan bahan serta ringan, ketahanan struktur dan tiada pengaratan. Walaupun penggunaan komposit dalam industri pesawat meningkat baru- baru ini, struktur komposit mempunyai masalah kecacatan daripada segi geometri dan dimensi yang disebabkan oleh pemprosesan. Perubahan rupa bentuk tidak dapat diduga dan menyumbang kepada ketidaksepadanan antara komponen yang dipasang. Selalunya, teknik tradisional yakni percubaan berulang-kali digunakan untuk memastikan kesesuaian pengilangan sebelum pengeluaran besar-besaran, yang sangat tidak ekonomi, mahal dan memakan masa. Terdapat kekurangan data eksperimen dan kajian mengenai kesan gaya tenunan yang berbeza seperti tenunan biasa (PW), tenunan 5 satin (5HS) dan tenunan 8 satin (8HS) dalam mempengaruhi bentuk perubahan komposit laminat yang berbentuk sudut tepat. Menggunakan rekabentuk ujikaji dengan faktorial pecahan dua peringkat iaitu 2^4-1 Resolusi IV dilakukan untuk mengkaji kesan utama dan interaksi pelbagai lapisan orientasi, jumlah lapisan, saiz sampel, bahan acuan serta gaya tenunan dalam mempengaruhi perubahan komposit laminat. Bahan komposit yang dipilih adalah serat karbon yang diperkukuhkan dengan resin epoksi yang boleh dipanaskan pada suhu tinggi 180 ° C dengan tekanan 7 bar dalam mesin pendandang. Berdasarkan kepada rekabentuk eksperimen dan analisa variasi, didapati orientasi ply, bilangan lapisan, saiz sampel dan gaya tenunan adalah faktor-faktor yang signifikan di dalam mempengaruhi kesan tenunan PW dan 8HS. Tenunan PW boleh mengakibatkan perubahan sudut komposit laminat sebanyak tiga kali ganda besar berbanding dengan tenunan 8HS. Hubungan ini adalah kuat dengan mempunyai nilai R² sebanyak 97.2% dan 87.9% untuk setiap acuan yang diperbuat daripada aluminium dan karbon. Sementara itu, hubungan tenunan PW dan 5HS, dan 5HS dan 8HS adalah sederhana dengan nilai purata R²sebanyak 66%. Dari segi interaksi, hanya tahap dua dapat menjejaskan rekabentuk yakni di antara orientasi ply dan acuan apabila faktor tenunan adalah kekal. Sebaliknya, majoriti tahap dua dari segi interaksi adalah di antara orientasi ply dan jumlah lapisan, dan orientasi ply dan sampel saiz apabila faktor acuan adalah kekal. Daripada ujian makmal, keputusan kadar pengembangan haba dan pengecutan kimia resin digunakan untuk mengira analisa ramalan dan dibandingkan dengan keputusan eksperimen. Pekali pengembangan haba dan pengecutan kimia pada arah ketebalan lebih besar sebanyak 10 hingga 18 kali ganda daripada dalam-satah yang mana ianya bergantung kepada jenis corak tenunan.

Malangnya, keputusan analisa ramalan dan eksprimen tidak sama berkemungkinan disebabkan oleh serat gentian tidak selari dan tergelincir, serta pengaruh bukan termoelastik yang tidak diambil kira. Walaupun begitu, kesan gaya tenunan tidak boleh diabaikan kerana secara statistik terdapat beberapa faktor-faktor utama dan interaksi yang mungkin dapat memberi kesan kepada perubahan rekabentuk komposit laminat berbentuk ‘L’.

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ACKNOWLEDGEMENTS

First and foremost, I am very grateful and thankful to Allah s.w.t., God Almighty, for giving me the health, energy, strength and perseverance to complete this dissertation. I would like to express my deepest gratitude and appreciation to my supervisor, Dato’

Professor Dr. Abu bin Abdullah from Faculty of Manufacturing Engineering of Universiti Teknikal Malaysia Melaka (UTeM) for his supervision, motivation and encouragement towards the completion of this thesis. Without his guidance and persistent support this thesis would not have been possible. I would also like to express my gratitude and appreciation to Professor Dr. Razali bin Muhammad from Pusat Pengajian Siswazah of UTeM who had been supervising and guiding me during the early days of my research project. I would like to extend my gratitude and appreciation to Professor Madya Dr.

Mohd. Rizal bin Salleh as my co-supervisor in guiding me in completing this thesis. In addition, special thanks to the Senior Management of CTRM who has supported my research project. I would like to thank my colleagues, friends and technicians in CTRM as well as others who had assisted me in completing my experimental works and testing.

Finally, I would like to express my appreciation and sincere thanks to my late father (Mohd. Sanusi), mother (Puteh), mother-in-law (Sena), wife (Jalilah) and children (Husaini, Marsya and Marissa) for their love, patience and encouragement.

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TABLE OF CONTENTS

PAGE DECLARATION

APPROVAL DEDICATION

ABSTRACT i

ABSTRAK ii

ACKNOWLEDGEMENTS iii

TABLE OF CONTENTS iv

LIST OF TABLES vii

LIST OF FIGURES xi

LIST OF ABBREVIATIONS AND SYMBOLS xix

LIST OF PUBLICATIONS xxiii

CHAPTER

1. INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 2

1.3 Research Objectives 7

1.4 Scope of Research Study 8

1.5 Thesis Outline 9

2. LITERATURE REVIEW 11

2.1 Composite Material 11

2.1.1 Fibre Reinforcement in Polymer Matrix Composite (PMC) 16

2.1.2 Polymer Matrix 17

2.2 Composite Processing Technologies for Polymer Matrix Composite 21

2.2.1 Hand Lay-up 21

2.2.2 Vacuum Bag Moulding 22

2.2.3 Oven and Autoclave Moulding 23

2.2.4 Resin Transfer Moulding and Vacuum-Assisted Resin Transfer Moulding 24

2.2.5 Pultrusion 26

2.2.6 Compression Moulding 26

2.2.7 Filament Winding 27

2.3 Part Geometries 28

2.4 Sources of Process Induced Shape Deformation 32

2.4.1 Residual Stresses 32

2.4.2 Thermal Expansion 35

2.4.3 Chemical Resin Cure Shrinkage 37

2.4.4 Curing Processing 39

2.5 Tooling 42

2.5.1 Tooling Material 42

2.5.2 Tooling Geometry 44

2.5.3 Open and Closed Form 45

2.6 Lay-up Configuration 47

2.6.1 Release Coating 47

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2.6.2 Stacking Sequence and Plies Orientation 48

2.7 Woven Fabric 50

2.8 Measurement Method of Shape Deformation 54

2.9 Non-Destructive Testing (NDT) 54

2.10 Material Characterization 56

2.11 Prediction of Shape Deformation in Composite Part 57

2.12 Design of Experiment (DOE) 59

3. RESEARCH METHODOLOGY 61

3.1 Design of Experiment (DOE) 63

3.2 Materials Selection 66

3.3 Tooling 66

3.4 Composite Manufacturing Processes 68

3.4.1 Mould Preparation 68

3.4.2 Cutting Materials 69

3.4.3 Lay-up 72

3.4.4 Autoclave 75

3.4.5 Demould 77

3.5 Measurements 78

3.5.1 Angularity 78

3.5.2 Weight 79

3.5.3 Thickness 79

3.6 Non-Destructive Testing (NDT) 80

3.7 Destructive Testing 81

3.7.1 Coefficient of Thermal Expansion (CTE) and Chemical Shrinkage (CS) 82

3.7.2 Glass Transition Temperature (Tg) 83

3.7.3 Fibre Volume Content 84

3.7.4 Tensile Strength and Modulus 85

3.7.5 Microscopic Analysis 86

4. RESULTS AND DISCUSSIONS 89

4.1 Measurements 89

4.1.1 Angularity 89

4.1.2 Weight 89

4.1.3 Thickness Measurement 91

4.2 Phase I: DOE and ANOVA 92

4.2.1 Effect of PW Fabric on Spring-in Angle with Fractional Factorial of 2^4-1

Resolution IV 92

4.2.2 Effect of 5HS Fabric on Spring-in Angle with Fractional Factorial of 2^4-1

Resolution IV 95

4.2.3 Effect of 8HS Fabric on Spring-in Angle with Fractional Factorial of 2^4-1

Resolution IV 99

4.2.4 Discussion 102

4.3 Phase II: DOE and ANOVA 105

4.3.1 Effect of PW and 5HS on Spring-in Angle with Aluminium Tool 106 4.3.2 Effect of PW and 8HS on Spring-in Angle with Aluminium Tool 108 4.3.3 Effect of 5HS and 8HS on Spring-in Angle with Aluminium Tool 111 4.3.4 Effect of PW and 5HS on Spring-in Angle with Carbon Tool 114

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4.3.5 Effect of PW and 8HS on Spring-in Angle with Carbon Tool 117 4.3.6 Effect of 5HS and 8HS on Spring-in Angle with Carbon Tool 120

4.4 Non-Destructive Testing 126

4.5 Destructive Testing 129

4.5.1 Coefficient of Thermal Expansion (CTE) 129

4.5.2 Chemical ShrinkageStrain 131

4.5.4 Glass Transition Temperature (Tg) 133

4.5.5 Fibre Volume (Vf) and Resin Content (Rc) 138 4.5.6 Tensile Modulus (TM) and Tensile Strength (TS) 141

4.5.7 Micro-Section Analysis 145

4.6 Discussion and Comparisons of Experimental and Analytical Prediction 149 4.6.1 Discussion and Comparison of Analytical Calculations and Experimental

Results 149

4.6.2 Discussion and Comparison of Measured In-plane CTEs with Rules of

Mixture Calculation 151

5. CONCLUSION AND FUTURE WORKS 153

5.1 Future Works 155

REFERENCES 156

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LIST OF TABLES

TABLE TITLE PAGE 1.1 Part geometries and its applications in aerospace composite structures

adapted from Soutis (2005) and Brauner et al. (2015)

3

1.2 Recent studies of composite shape deformation using different part geometries, weaving styles, part configuration, type of materials and processing technology

7

2.1 Summary of matrix phases with is reinforcement and matrices (Callister, 2006, Sinha, 2006, Balasubramanian, 2013)

14

2.2 Summary of matrix phases with its advantages, disadvantages, processing techniques and applications (Callister, 2006, Sinha, 2006, Balasubramanian, 2013)

15

2.3 Material properties of several fibre-reinforcement materials (Callister, 2006)

18

2.4 Typical thermoset resin materials properties (Sinha, 2006) 20 2.5 Typical thermoplastic resin materials properties (Sinha, 2006) 20 2.6 Summary of advantages and disadvantages between thermoset and

thermoplastic resin (Steinbüchel, 1995, Gilleo and Ongley, 1999)

21

2.7 Thermo-mechanical level with its coordinate system and length scale of stress (Johnston, 1997)

33

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2.8 Past research studies using woven fabrics other than unidirectional 52 2.9 Comparison of different weaving styles and properties (Aliabadi, 2015) 53 3.1 Phase I - Fractional factorial of 24-1 Resolution IV with low and high

setting where the weaving style will be kept constant for PW, 5HS and 8HS in the ANOVA analysis

65

3.2 Phase II - Fractional factorial of 24-1 Resolution IV with low and high setting where the tool material (aluminium or carbon) will be kept constant

65

3.3 Experimental design matrix using Minitab software for fractional factorial 24-1 Resolution IV

66

3.4 Materials properties of different weaving styles (Anonymous, 2010) 66

3.5 Magnification Levels for NK Vision Microscope 88

3.6 Magnification Levels for Olympus 88

4.1 Weight calculation and measurement for each composite laminate 90 4.2 Thickness calculation and measurement for each laminate 91 4.3 Spring-in angle measurement for PW composite laminates 93 4.4 ANOVA experimental results for spring-in angle of L-shaped

composite laminates with PW fabric (α = 0.05)

94

4.5 Spring-in angle measurement for 5HS composite laminates 97 4.6 ANOVA experimental results for spring-in angle of L-shaped

composite laminates with 5HS fabric (α = 0.05)

97

4.7 Spring-in angle measurement for 8HS composite laminates 100 4.8 ANOVA experimental results for spring-in angle of L-shaped

composite laminates with 8HS fabric (α = 0.05)

100

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4.9 Comparison of significance factors affecting spring-in angles of PW, 5HS and 8HS composite parts where ‘-’ and ‘X’ denotes insignificant and significant factor respectively

104

4.10 Regression equations with R-squared and standard error for spring-in angle (‘Y’) of PW, 5HS and 8HS fabric where ‘A’, ‘B’, ‘C’ and ‘D’

denotes plies orientation, no. of layers, sample sizes and tool materials respectively

104

4.11 Spring-in angle measurement for PW and 5HS composite laminates 106 4.12 ANOVA experimental results for spring-in angle of L-shaped

composite laminates between PW and 5HS (α = 0.05)

107

110

4.15 Spring-in angle measurement for 5HS and 8HS composite laminates 112 4.16 ANOVA experimental results for spring-in angle of L-shaped

composite laminates between 5HS and 8HS (α = 0.05)

113

115

118

4.21 Spring-in angle measurement for 5HS and 8HS composite laminates 120 4.22 ANOVA experimental results for spring-in angle of L-shaped 121

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composite laminates between 5HS and 8HS (α = 0.05)

4.23 Comparison of significance factors affecting spring-in angles of PW vs. 5HS, PW vs. 8HS and 5HS vs. 8HS composite parts where ‘-’ and

‘X’ denotes insignificant and significant factor respectively

125

4.24 Regression equations with R-squared and standard error for spring-in angle (‘Y’) of PW vs. 5HS, PW vs. 8HS and 5HS vs. 8HS fabric with aluminium tool where ‘A’, ‘B’, ‘C’ and ‘D’ denotes plies orientation, no. of layers, sample sizes and weaving styl

125

4.25 Regression equations with R-squared and standard error for spring-in angle (‘Y’) of PW vs. 5HS, PW vs. 8HS and 5HS vs. 8HS fabric with carbon tool where ‘A’, ‘B’, ‘C’ and ‘D’ denotes plies orientation, no.

of layers, sample sizes and weaving styles

126

4.26 Test samples 127

4.27 Range of ultrasonic level in decibel penetrating various thicknesses made from PW, 5HS and 8HS

128

4.28 Summary of Tg Onset 137

4.29 Experimental data of fibre volume and resin volume for woven fabrics 139 4.30 Calculated residual stress and the measured height of the deflection of

flat laminates

144

4.31 Comparison of predicted spring-in angles with experimental data (standard deviation in parentheses)

151

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LIST OF FIGURES

FIGURE TITLE PAGE 1.1 The materials breakdown for Boeing 787 airframe (Hale, 2006, Nayak,

2014)

2

1.2 Intrinsic and extrinsic variables known to affect geometrical instability of composite structure where score 3, 2, 1 and 0 indicates large, medium, small and least effect respectively (Svanberg, 2002)

6

2.1 Category of natural and synthetic fibres (Jawaid and Abdul Khalil, 2011)

12

2.2 Classification of composite types (Callister, 2006) 13 2.3 Traditional manual lay-up process (Campbell, 2004) 22 2.4 Production process of prepreg with thermoset resin (Callister, 2006) 22 2.5 Bagging sequence for flat composite laminates (Mezeix et al., 2015) 23 2.6 Autoclave forming process for composite parts (Hoa, 2009) 24 2.7 RTM manufacturing process flow (Campbell, 2004) 25 2.8 VARTM processing schematic diagram (Song, 2003) 25

2.9 Pultrusion process flow (Meyer, 1985) 26

2.10 Compression molding schematic diagram (Davis et al., 2003) 27 2.11 Filament winding process (Askeland et al., 2011) 28 2.12 Flat composite laminate, (a) no change in geometrical shape during

curing process and (b) after end of cure the laminate warps out of

30

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plane (Radford, 2010).

2.13 Cured shapes of composite laminates. (a) At the curing temperature, (b) saddle shape, (c) and (d) cylindrical shapes (Ren et al., 2003).

30

2.14 Spring-in angle before and after cure (Radford and Diefendorf, 1993, Radford and Rennick, 2000)

32

2.15 A schematic set-up of the Moiré´ Interferometry for the FBGS technique (Mulle et al., 2007)

36

2.16 Curing of thermoset resin (a) monomer stage, (b) linear growth and branching, (c) formation of gelled but incompletely cross-linked network, and (d) fully cured thermoset (Garstka et al., 2007).

38

2.17 Stresses in fibre and matrix during cure cycle, (a) compressive stress occurs in fibres during volumetric shrinkage and (b) tensile stress during thermal expansion (Russell et al., 2000)

39

2.18 Material properties change of a thermosetting polymer matrix during a typical curing process (Johnston, 1997).

41

2.19 The physical properties of polymer matrix change throughout the curing process are divided into three regions where Vi is the specific volume at gelation, and Vf is the specific volume at 100% cure (Shah and Schubel, 2010).

41

2.20 CTE mismatch between mould tool and composite laminate upon completion of curing process (Fernlund et al., 2002c, Potter et al., 2005)

43

2.21 CTE of different tooling materials (Burden, 1989, Burke, 2003) 44

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2.22 Part-tool interaction reduced shape distortion of composite part when using concave tool instead of convex tool (Radford, 2010).

45

2.23 Schematic representation of open and mould process: (a) before the cure and (b) at the end of the cure (Palardy et al., 2008, Khoun and Hubert, 2010).

46

2.24 The effect of the use of FEP release film against mould release agent (Ersoy et al., 2005b)

48

2.25 Thermal expansion for ply orientation (Hubert and Poursartip, 2001) 49 2.26 Types of weaving styles in a fabric (Anonymous, 2010) 53 2.27 Through-transmission utilizing ultrasonic technique with a transmitter

and a receiver (Kapadia, 2007)

55

2.28 Typical A-scan display of pulse-echo (Kapadia, 2007) 56 2.29 Micrographs of the cross section of (a) plain weave and (b) 8H satin

weave (Rinn, 2014).

57

2.30 SEM micrograph of 8HS composite plaque (Searles et al., 2001) 57 3.1 Activities in determining the effects of input variables to the shape

deformation of angled composite laminates

62

3.2 Overview of the input variables, DOE and output response 63 3.3 Mould tools made from (a) carbon and (b) aluminium material 67 3.4 Flowchart of typical composite manufacturing processes 68

3.5 Flowchart of cutting materials 70

3.6 Gerbercutter DCS3500 machine 71

3.7 Nesting file for cutting purpose 71

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3.8 Coordinate system for fibre direction for L-shaped composite laminate where the longitudinal direction is along the 0° direction and the transverse direction is following the 90° direction (Mohd Sanusi and Abdullah, 2015)

73

3.9 Ancillary materials used in the debulking process and final bagging process

75

3.10 Manufacturer recommended curing cycle for curing composite laminates (Anonymous, 2010)

76

3.11 Autoclave machine 77

3.12 Cured composite laminates 78

3.13 CMM for angular measurement 79

3.14 MIDAS Flatbed Ultrasonic machine 80

3.15 NDT reference standard 100 x 100 ml with artificial defects at the middle of laminate

81

3.16 Test specimens extraction location from L-shaped composite laminate with the required test specification method and dimension

82

3.17 Dilatometer equipment. Courtesy of UniMAP. 83

3.18 Dynamic Mechanical Analyzer. 84

3.19 Measuring equipment as part of acid digestion process 85

3.20 Universal Testing Machine 86

3.21 Grinder and Polisher Machine 87

3.22 High Magnification Microscopes (a) Olympus and (b) NK Vision 87 4.1 Comparison of calculated weight and measured weight for each

laminate

90

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4.2 Comparison of calculated thickness and measured thickness for each laminate

92

4.3 Main effect plots of spring-in angle using PW fabric vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) tool materials

94

4.4 Interaction plots of spring-in angle using PW fabric vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) tool materials

95

4.5 Main effect plots of spring-in angle using 5HS fabric vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) tool materials

98

4.6 Interaction plots of spring-in angle using 5HS fabric vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) tool materials

98

4.7 Main effect plots of spring-in angle using 8HS fabric vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) tool materials

101

4.8 Interaction plots of spring-in angle using 8HS fabric vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) tool materials

101

4.9 Spring-in angle of L-shaped composite laminates with different plies orientation, number of layers, sample sizes, tool materials and woven fabrics.

105

4.10 Main effect plot of spring-in angle of PW and 5HS vs. (a) plies orientation, (b) number of layers, (c) sample sizes and (d) weaving style

107

4.11 Interaction plots of spring-in angle for PW and 5HS vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) weaving styles

108

4.12 Main effect plot of spring-in angle of PW and 8HS vs. (a) plies orientation, (b) number of layers, (c) sample sizes and (d) weaving

110

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style

111

4.14 Main effect plot of spring-in angle of 5HS and 8HS vs. (a) plies orientation, (b) number of layers, (c) sample sizes and (d) weaving style

113

114

116

119

4.20 Main effect plot of spring-in angle of 5HS and 8HS vs. (a) plies orientation, (b) number of layers, (c) sample sizes and (d) weaving style

121

4.21 Interaction plots of spring-in angle for 5HS and 8HS vs. (a) plies orientation, (b) no. of layers, (c) sample sizes and (d) weaving styles

122

4.22 Ultrasonic scanning results for A (PW [0]8), B (PW [0/-45/45/90]s), C 127

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(5HS [0]8), D (5HS [0/-45/45/90]s), E (8HS [0]8) and F (8HS [0/- 45/45/90]s)

4.23 Portable A-scan probe of Epoch 600 scanning corner radius of angled composite laminate

128

4.24 The coefficient of thermal expansion of PW, 5HS and 8HS composite laminates in the in-plane and through-thickness direction with plies orientation of [0]8 and [0/-45/45/90]s

130

4.25 The chemical shrinkage strain of PW, 5HS and 8HS composite laminates in the in-plane and through-thickness direction with plies orientation of [0]8 and [0/-45/45/90]s

132

4.26 Tg result for PW with [0]8 plies orientation 134 4.27 Tg result for PW with [0/-45/45/90]s plies orientation 134 4.28 Tg result for 5HS with [0]8 plies orientation 135 4.29 Tg result for 5HS with [0/-45/45/90]s plies orientation 135 4.30 Tg result for 8HS with [0]8 plies orientation 136 4.31 Tg result for 8HS with [0/-45/45/90]s plies orientation 136 4.32 Dried fibres after acid digestion process during Vf testing 138 4.33 Comparison of fibre volume of different weaving styles and plies

orientation where the recommended value is based on material data (Anonymous, 2010).

139

4.34 Comparison of resin volume of different weaving styles and plies orientation where the recommended value is based on material data (Anonymous, 2010).

140

4.35 Tensile strength for PW, 5HS and 8HS composite laminates 142

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4.36 Tensile modulus for PW, 5HS and 8HS composite laminates 142 4.37 A typical acceptable failure mode of fibre breakout on mould tool’s

side surface

143

4.38 A typical acceptable failure mode of fibre breakout on bagging’s side surface

143

4.39 Microsection analysis of PW [0]8 using (a) NK Vision with 3X magnification and (b) Olympus with 10X magnification

146

4.40 Microsection analysis of PW [0/-45/45/90]s using (a) NK Vision with 3X magnification and (b) Olympus with 10X magnification

146

4.41 Microsection analysis of 5HS [0]8 using (a) NK Vision with 3X magnification and (b) Olympus with 10X magnification

147

4.42 Microsection analysis of 5HS [0/-45/45/90]s using (a) NK Vision with 3X magnification and (b) Olympus with 10X magnification

147

4.43 Microsection analysis of 8HS [0]8 using (a) NK Vision with 3X magnification and (b) Olympus with 10X magnification

148

4.44 Microsection analysis of 8HS [0/-45/45/90]s using (a) NK Vision with 3X magnification and (b) Olympus with 10X magnification

148

4.45 Comparison of predicted spring-in angle with experimental data 151 4.46 Comparison of measured and predicted CTEs using rules of mixture 152

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LIST OF ABBREVIATIONS AND SYMBOLS

ACT Advanced Composite Tool

AITM Airbus Industries Testing Method ASTM American Standard Testing Method ANOVA Analysis of variance approach

BMC Bulk-moulding compound

CMC Ceramic Matrix Composite

∆T Change in temperature

CS Chemical shrinkage

CTE Coefficient of thermal expansion

CTRM Composites Technology Research Malaysia CMM Coordinated Measuring Machine

∆θCS Cure shrinkage

DOF Degree of freedom

DOE Design of experiment

DDM Direct Differentiation Method DMA Dynamic Mechanical Analyser 8HS Eight harness satin

Ef Elastic modulus fibre

Em Elastic modulus matrix