Micro-Stress Analysis of Woven Fabric Composites by Multilevel Decomposition

A new micromechanics model is presented to predict the local stresses within woven fabric composites under three-dimensional mechanical loading. The model accounts for fabric geometry, yam interactions and matrix distribution. First, by constructing a multilevel decomposition scheme, the composite unit-cell is split up into matrix and yam cells. Then, by a multistep homogenization procedure, a link is established between the external loading and the internal stresses. The principle idea lies in the interpretation that the "stress concentration factors" can be computed at each step by applying the complementary variational principle. We achieve a straightforward analytical stress model for woven fabric composites which has not yet been reported. In addition to modeling the stress fields, the three-dimensional stiffness matrix is computed in this paper using the "stress concentration factors." The proposed modeling technique yields numerical stiffness results comparable to those obtained by three-dimensional finite element modeling.