Elastic-plastic analysis of interlaminar stresses in composite laminates due to bending and torsion

Abstract

The elastic-plastic response of interlaminar stresses in composite laminates due to bending and torsion is investigated using the finite element method. The plasticity model used is a general three-dimensional orthotropic yield criterion, which is quadratic in stresses, in conjunction with incremental flow theory. Linear and nonlinear studies are carried out with boron-aluminum metal-matrix composites. The results, including bending moment-curvature relations, growth of plastic zones, and distribution of interlaminar stresses, are presented. It is found that the free edge effect on interlaminar stresses is important in bending, but it is insignificant in torsion. It is also shown that the inclusion of plasticity could alter free edge interlaminar stresses significantly.