3-D geometric modeling of a draped woven fabric

One of the components required for design and optimisation of fabric reinfo rced products is a realistic and accurate 3-D geometry model for a repeatin g element of the reinforcement. Such a model, which reflects the deformatio ns that result from weaving the fibre bundles and forming (draping) the wov en fabric over a product mould, is proposed in the present paper. A fibre b undle architecture, which exhibits undulation and variable cross-section di mensions, is introduced to this effect. Every bundle is described by its in -plane centreline path, its double curved horizontal midplane and the thick ness distribution of the cross-sections. These parameters are, in turn, def ined by invariant shape functions and variable fibre bundle dimensions. The selected geometry description enables straightforward determination of ind ividual fibre paths. In order to verify the model experimentally, cross-sec tions are cut out from undeformed laminates with plain-weave reinforcements , and laminates of which the plain-weaves have been subjected to stretching or shear deformations during draping. The laminate cross-sections are made along and perpendicular to the mean directions of the impregnated fibre bu ndles (yarns). All yams exhibit out-of-plane undulation and curvature and t wist of the midplane. Correlation between experiment and the proposed model ing scheme is good. Draping results in significant fibre reorientations and variations between the individual fibre paths, which are not reflected by existing modeling schemes. These geometry deviations may significantly affe ct the stress distribution, and should be taken into account in order to pr edict material properties accurately. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.