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Title: Structural mechanics of woven preforms and textile composites
Author: Thammandra, Vidya Sagar
ISNI:       0000 0001 3516 5946
Awarding Body: Manchester
Current Institution: University of Manchester
Date of Award: 2005
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The present work deals with the development of comprehensive mechanical models to predict the mechanical properties of woven fabric structures, namely the tensile, bending and compression behaviour. All the models are based on the Rayleigh-Ritz energy method, which allows handling non-linear mechanical properties of constituent yarns while producing computationally efficient algorithms. The models incorporate all modes of deformation, i.e., yarn elongation, yarn bending and yarn compression. An effort has been made to make the models more general by considering generalised geometry with adequate degrees of freedom to represent the yarn path under all deformed configurations. A new geometric model based on polynomial geometry has been developed and it has been shown that the mechanical models based on the new geometry closely simulate fabric tensile behaviour. The model developed for plain woven fabric has been generalised to predict the tensile behaviour of regular non-plain woven fabrics by specifying the number of crossovers and number of floats in a weave repeat and it was shown to give consistent predictions for different fabric structures. The pure bending behaviour of plain woven fabrics has been studied considering both a single 5th degree polynomial and a piecewise Hermite polynomial geometry. The deformed state is obtained using the principle of stationary potential energy without invoking work-energy theorem and hence they predict the complete moment-curvature relationship of fabric. The compression behaviour of single fabric has been studied by characterising the yam compression behaviour using an inverse method and the compression behaviour of double fabrics has also been modelled. The solution of models using non-linear programming constrained minimisation techniques has been demonstrated using readily available optimisation software. The models have been validated against the data reported in the literature along with the experimental results of glass fabrics. The predictions of models have also been compared against the results of Finite Element Analysis (FEA) using the general purpose FEA software ABAQUS. The compaction of fabric between two rigid plates has been simulated using 3D FEA. The geometry of yarn path derived from the mechanical models has been used to construct 3D FEA models for studying the micro-mechanical behaviour of plain woven fabric composites.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available