Contents
The Textile Institute and Woodhead Publishing ii
Woodhead Publishing in Textiles ix
Preface xv
Acknowledgements xviii
1.1 assemblies 1
1.2 Two-dimensional structures (two-dimensional fabrics) 2
1.3 Limitations of two-dimensional textile structures 7
1.4 Three-dimensional structures (three-dimensional fabrics) 8
1.5 Conclusions 30
1.6 References 31
2 Applications of three-dimensional textiles 33
2.1 Introduction 33
2.2 Application of three-dimensional fabrics to composites 34
2.3 Application of three-dimensional fabrics to medical textiles 50
2.4 Application of three-dimensional fabrics to sports 53
2.5 Application of three-dimensional fabrics to geotextiles 56
2.6 Application of three-dimensional fabrics to automotives 60
2.7 Application of three-dimensional fabrics to protective
clothing and the aerospace industry 62
2.8 References 66
3 Multiaxial warp-knitted fabrics 70
3.1 Introduction to multiaxial warp-knitted fabrics 70
3.2 Advantages of multiaxial warp-knitted fabrics 72
3.3 Manufacture of multiaxial warp-knitted fabrics 73
Introduction to three-dimensional fibrous assemblies
Introduction: concepts of three-dimensional fibrous
3.4 General structure and behaviour of multiaxial warpknitted fabrics 81
3.5 Applications of multiaxial warp-knitted fabrics 97
3.6 Summary 100
3.7 References 101
4 Multilayer woven fabrics 104
4.1 Introduction to multilayer woven fabrics 104
4.2 Advantages of multilayer woven fabrics 105
4.3 Manufacture of multilayer woven fabrics 106
4.4 General structure and behaviour of multilayer woven fabrics 113
4.5 Applications of multilayer woven fabrics 127
4.6 Summary 129
4.7 References 130
5 Tensile properties of multiaxial warp-knitted fabrics 131
5.1 Introduction 131
5.2 Tensile behaviour of multiaxial warp-knitted fabrics 132
5.3 Modelling tensile properties of multiaxial warp-knitted fabrics 139
5.4 Experimental methods and validation 147
5.5 Conclusions 149
5.6 References 151
6 Bending properties of multiaxial warp-knitted fabrics 153
6.1 Introduction 153
6.2 Bending properties of multiaxial warp-knitted fabrics 155
6.3 Bending hysteresis curves of multiaxial warp-knitted fabrics 159
6.4 Buckling of the bent-inserting yarns 162
6.5 Effect of bending sequence on bending hysteresis curves 162
6.6 Cyclic bending 163
6.7 Modelling bending properties of multiaxial warp-knitted fabrics 164
6.8 Model validation 169
6.9 Conclusions 171
6.10 References 173
7 Formability of multiaxial warp-knitted fabrics 174
7.1 Introduction 174
7.2 Textile composite deformation mechanisms 176
7.3 Structure of multiaxial warp-knitted fabrics 179
7.4 Deformation characteristics of woven fabrics during the forming process 180
7.5 Deformation characteristics of multiaxial warp-knitted fabrics during the forming process 180
7.6 Deformation behaviour of two-bias multiaxial warpknitted fabrics 182
7.7 Modelling the formability of two-bias multiaxial warpknitted fabrics 188
7.8 Summary 190
7.9 References 192
8 Permeability of multilayer woven fabrics 194
8.1 Introduction 194
8.2 Fabric compressibility 200
8.3 Permeability testing 201
8.5 Fractal permeability model 214
8.6 Conclusions 216
8.7 References 217
9 Using multilayer woven fabrics in resin transfer moulding 221
9.1 Introduction 221
9.2 Flow resistance of multilayer woven fabrics 223
9.3 Flow modelling of multilayer woven fabrics 225
9.5 Modelling the effect of stitch size, distribution and position 237
9.6 Conclusions 251
9.7 References 252
Preface
3-D woven, knitted, braided or stitched fibrous assemblies are textile architectures having fibres oriented so that both the in-plane and transverse tows are interlocked to form an integrated structure that might have a unit cell with comparable dimensions in all three orthogonal directions. This integrated architecture provides improved stiffness and strength in the transverse direction and impedes the separation of in-plane layers in comparison to traditional 2-D fabrics. Recent automated manufacturing techniques have substantially reduced costs and significantly improved the potential for large-scale production of such structures.
I always felt that a comprehensive book on 3-D fibrous assemblies would provide a great support for the industry and for research/educational institutions in understanding the concepts of these new fabric architectures to develop new products for specific applications such as in composites, medical, sports, geotechnical and aerospace fields.
Hence, this book is the culmination of research into 3-D textiles and their applications to composites and other related areas and is based on thorough and detailed compilation of various topics related to 3-D fibrous assemblies. The detailed information provided in this book has been the collective compilation of works of various researchers in the field, mainly from our own research studies, especially on modelling of multiaxial warp-knitted and multilayer woven fabrics.
The book consists of nine chapters covering the topics from introduction of 3-D fibrous assemblies such as 3-D woven, knitted, non-woven and braided fabrics to the advanced modelling of these fabrics for various applications.
Chapter 1 introduces the various 3-D fibrous assemblies such as 3-D woven fabrics, multiaxial warp-knitted structures, 3-D braided, stitched and non-woven fabrics and their general structures. The principle of production of these fabrics with their advantages over 2-D fabrics is also discussed.
Chapter 2 is an overview of the various applications of these fabrics in composites, medical, aerospace and other fields. Specific applications of 3-D woven, knitted, braided and non-woven fabrics in composite manufacture are discussed in detail.
In Chapter 3 a detailed discussion of the structures and manufacturing methods of multiaxial warp-knitted fabrics is presented. The advantages of these fabrics over other fabrics are discussed. In addition, detailed information on various mechanical properties such as tearing, shear, compression and flexural behaviour of these fabrics is also presented in this chapter.
Chapter 4 provides in-depth information on structures of various multilayer woven fabrics and their manufacturing methods. Various routes to manufacture these fabrics are discussed in detail with suitable illustrations. At the end, detailed information is available on their mechanical properties such as tensile, shear and compression with a brief section on applications of these fabrics.
Chapters 5 to 9 are devoted to the modelling of various preforms of multiaxial warp knits and multilayer woven fabrics. In Chapter 5 an attempt has been made to discuss in detail some of the modelling techniques used to understand the tensile behaviour of multiaxial warp-knitted fabrics. A macroscopic approach dealing with fabric structure under uniaxial tensile deformation is developed for a greater understanding of the geometry of these fabrics. A model for uniaxial tensile deformation is obtained, which is justified by Instron 4466 tensile testing. In addition, a formula for calculating the tensile modulus of the fabric in any direction is presented.
Chapter 6 describes the modelling methods used to analyze the bending behaviour of MWK fabrics. An elaborate description and interpretation on the bending properties of MWK fabrics are presented, which are based on many bending hysteresis curves obtained on KES-FB-2. Further, a predictive bending model to assess the MWK fabrics based on KES-F experiments in different bending directions is described.
In Chapter 7 a model for the prediction of the formability of a multiaxial warp-knitted (MWK) fabric to a 3-D surface is described. Fibre and yarn movement during fabric forming can cause adverse effects such as wrinkling and thinning, which will lead to a decrease of the mechanical properties of the finished composite. In addition, the high level of waste generated by subsequent trimming operations is unacceptable. Hence there was a need to establish a model to predict the deformation and possible wrinkles of MWK fabrics during the forming process in order to enable waste-free design and defect predictability. For this purpose, a detailed characterization of the forming behaviour of MWK fabrics containing two bias inserting yarns (TBMWK fabric) is discussed in this chapter.
Chapter 8 presents a comprehensive study on the permeability modelling of multilayer woven fabrics. A framework for flow permeability measurement in resin transfer moulding is discussed. The Darcy law is used to model the flow through the reinforcement fibres where permeability is a measure of the resistance of the fibres to the flow. Two types of woven fabrics, one fabricated by the monofilament method so as to eliminate the effects of other factors such as fibre bundle on permeability, and the other by using multifilament yarns, are used for modelling. Two models are developed to explain the permeability of these two different varieties of multilayer woven fabrics.
Finally, in Chapter 9 a detailed theoretical analysis for in-plane impregnation in multilayer woven fabrics is reported in order to understand the mechanism of void formation. Unlike the previous approaches, where the void is formed in the plane of one layer of woven fabric, the void formation in the cross-section of multilayer woven fabrics is presented. Based on two simplified unit cells, which were identified from two typical multiple modes of multilayer woven fabrics, a mathematical model is developed to analyze the formation and size of voids. The flow front and void formation processes are also numerically simulated using the control-volume method.
I sincerely feel that the readers will find the book both interesting and informative as it contains the state of the art information on 3-D fibrous assemblies and their application in various fields.
Professor Jinlian Hu