Compaction of woven-fabric preforms in liquid composite molding processes: single-layer deformation

A theoretical study of elastic deformation during the compaction of woven-fabric preforms in liquid composite molding processes is presented in this paper. The analysis focuses on the unit cell of an orthogonal plain-weave fibrous preform, which is composed of two sets of mutually orthogonal yarns. A 3D model of the unit cell has been proposed with certain assumptions and been used to predict the compressive behavior of yarns. On the basis of this model and beam theory in the mechanics of materials, analytical expressions for relations among the fiber volume fraction, the applied compressive force and the preform thickness reduction have been established. A prediction of the limiting fiber volume fraction is also obtained. The results of this study also have significant implication in the understanding of preform permeability in liquid composite molding processes. (C) 1999 Elsevier Science Ltd. All rights reserved.