Unit-cell geometry in plain-weave fabrics during shear deformations

The evolution of microstructure in dry plain-weave fabric during large shear deformation is described. The entire geometry of the unit cell is defined by four sinusoidal curves in terms of the yam width, yarn spacing and fabric thickness. The change in micro-structural throughout shear deformation prior to wrinkling is predicted by using only measured parameters from the undeformed fabric. Comparisons between the predicted and experimental values are included. The microstructure is shown to evolve considerably prior to wrinkling. Expressions relating fiber volume fraction to the level of shear deformation are also presented. The possibility that unit-cell volume fractions may vary by a factor of two in parts with complex curvature is shown to exist. Implications for manufacturing issues such as preform permeability and thermal conduction during forming and for mechanical property prediction of textile composites are discussed. (C) 1997 Elsevier Science Limited.