Failure analysis of laminated composites by using iterative three-dimensional finite element method

Abstract

In this paper, a failure analysis of laminated composites is accomplished by using an iterative three-dimensional finite element method. Based on Tsai-Wu failure theory, we first propose three different modes of failure, namely, fiber breakage, matrix cracking and delamination. The first-ply failure load is then evaluated. As the applied load exceeds the first-ply failure load, localized structural failure occurs and the global structural stiffness should change. We modify the global stiffness matrix by taking nonlinearity due to partial failures within a laminate into consideration. The first-ply failure load is analyzed by using an iterative mixed field in solving the linear part of the finite element equations. The progressive failure problem is solved numerically by using Newton-Raphson iterative schemes for the solution of nonlinear finite element equations. Numerical examples include a three-layered cross-ply (0/90/0) E-glass-epoxy and an angle-ply four-layer Thornel 300 graphite-934 resin epoxy laminates under uniaxial tension in both cases. First-ply failure loads as well as the final loads are evaluated. Good correlation between analytical results and experimental data are observed. Numerical results also include the investigation of composite specimens with a centered hole, under uniaxial tension. First-ply failure loads and final failure loads are obtained by using the finite element program. Excellent correlation with the experimental data is observed.