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Papers: |
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For flat sheets, the usual ways of making fibre reinforced plastics (FRP) are random short fibre
placements, which have the disadvantage of discontinuities at fibre ends, and multi-layer laminates
of filament prepregs or 2D textile fabrics. For 3D shell structures, filament winding, press-forming
and fabric draping are used. Integral 3D fabrics are an attractive alternative. They can be made in a
variety of ways, but those most relevant to FRP bridges are woven fabrics consisting of (1) thick
multilayers linked by threads in the Z-direction either flat or (2) made in more complicated 3D
shapes, (3) hollow multilayer fabrics containing voids. Braids may also be used.
The advantages of 3D woven fabrics for composites are:
- resistance to delamination and improved through-thickness properties
- ease of handling for assembly of components for impregnation and auto-claveing or for
- thermal bonding
- manufacture on commercial weaving machines with limited modification
- economy of production, especially if large volumes are needed
- competitive with steel, particularly if glass or polyester yarns are used for reinforcement..
The paper will describe the structures that are available, design procedures and manufacturing
methods. The results of a case study for a small footbridge composed of three parts, the travel
surface made from floor beams, stringers and the deck, and two side-structures serving as girders.
The loading capacity of the bridge comes from the strengths of the floor beams, stringers and the
girders.
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The last 65 years have seen a development of modelling of the structural mechanics of textiles at the same time as computation moved from primitive calculations to powerful software and hardware. The development of means of access to computing is described. Early work could only deal with numerical solutions at the end of analyses of simple, general models. Now it is possible to follow individual fibre elements in space and time. The paper reviews topics covered by myself and my associates in the University of Manchester and elsewhere after my retirement: fibre fine structure; yarn mechanics; fabric mechanics; product mechanics; and rope modeling. The final part of the paper discusses modeling for the 21st century, including the problem of the “virtual catwalk” and the development of software for 3D fabrics used in composites. In contrast to aesthetic design where computer aided design (CAD) has become the common mode, the industry has not taken to modeling for technical textiles. This means that there is a lack of creative interchange between academia and industry. CAD is bound to come, but it is not possible to say when and how. |
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3D textile structures provide many unique structural features that are of interest to the creation of advanced textile composite, these including the structural integrity, material continuity, versatility in fibre arrangement, dimensional control of the preforms and economy in manufacturing. Because of these features, 3D textiles as preforms for textile composites have caused much attention and 3D textile structures have been made based on various principles. This paper concentrates on 3D woven preforms, which are capable of being produced using the weaving technology widely available in the textiles sector. Design and manufacturing of 3D woven preforms with solid, hollow, shell and nodal geometries and their derivatives will be explained and their featured properties be examined. Case studies will be given to highlight the application of such 3D woven preforms. |
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The engineering design of textiles continues to follow the traditional empirical methods, and, for technical as distinct from aesthetic design, has not adopted CAD as used in other industries. The reasons for this and the need for change are discussed. The paper reviews the state of the art in the structural mechanics of yarns and fabrics. The major challenge is to develop programs that industry will use and so open up a creative interchange between academic researchers and industrial users. A description of key features of TexEng, which an easy-to-use program aimed at meeting this challenge, is given. |
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TexEng Software Ltd enables you to
design 3D woven fabrics and program
their weaving machines for their
production. For more details, please send email to:
info@texeng.co.uk. |
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With a few years overlap at each end, the second half of the 20th Century has seen the rise of computing, as indicated below, and the study of the structural mechanics of fibres and fibre assemblies ¨C as well as coinciding with the professional career of the presenting author (jwsh). An account of the history is instructive, but more attention will be paid to matters of current concern, particularly the TechniTex core research in the University of Manchester on the modelling of woven fabrics and the work of jwsh with Canesis Network Ltd (formerly Wool Research Organisation of New Zealand) on wool and hair. The paper will progress from the nano-scale of molecular structures, through the micromechanics of fibres, yarns and fabrics, to the macromechanics of overall performance of products. |
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Textiles have developed as high-quality materials on the basis of highly developed but empirical craft skills. The second half of the 20th century resulted in many academic papers on the analysis of the applied mechanics of fibre assemblies. However, although these researches led to useful qualitative insights, there was almost no quantitative application by industry. Several factors cause the time to be now ripe for a change to an engineering design culture. There are major challenges in dealing with assemblies of millions of fibres, with nonlinear, visco-elastic-plastic mechanical properties, in anisotropic structures subject to large deformations and strains. The paper describes two approaches to accessible modeling, fibre rope modeling and TechTextt CAD. The most useful methodology for modeling yarns, woven fabrics and fabric buckling is discussed. The priority is to develop software that industry uses, thus setting up a creative interchange, which will lead to advances. |
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The knowledge of mechanical behaviour of woven performs under uniaxial/biaxial tensile loads is necessary to predict the changes in perform geometry during processing of composites. The aim of this study is to highlight the advantages of energy based approach to solve fabric mechanics problems with out the necessity of complex 3D finite element analysis. A mechanical model to predict the tensile response of plain-woven fabric under in-plane uniaxial/biaxial loads is presented here. The model incorporates non-linear properties of constituent yarns, rather than idealised linear behaviour. All possible mechanisms of deformation including elongation, bending and compression of yarns have been considered. The predictions are compared with experimental data reported in literature and the results are discussed. The computational aspects of implementation of the model are also discussed briefly. |
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Mechanics of textile fabrics by modelling of equilibrium of forces is different to apply broadly in practical applications. An alternative, which offers more promise for industrial utility in computer-aided design, is the energy-based approach described by Hearle and Shanaham (1978a,b). The paper reviews the basic principles and considers the ways of introducing appropriate energy terms to cover yarn extension, yarn bending, yarn flattening, and friction at crossovers. The main discussion is given for the elastic response of simple, plain-weave fabrics, based on several different geometric models, but the ways to deal with other fabrics and conditions are also suggested. The paper provides a protocol for advancing the subject from academic research to commercial use. |
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