Failure analysis of laminated structures by FEM based on nonlinear constitutive relationship

Nonlinear characteristic of matrix material is considered in the Bridging Model constitutive theory for composite materials. The model is consistent in that the laminate nonlinear constitutive equations automatically deteriorate to those of the isotropic matrix material when the fiber content becomes zero or when the fiber becomes the same as that of the matrix. This model is programmed into UGENS subroutine of the commercial finite element code ABAQUS for analyzing the nonlinear response and ultimate strength of composite laminates readily. In the paper, the influence of different load increments, mesh scales, and stiffness discount schemes on the finite element (FE) analyzed results has been studied. Strength envelopes and stress–strain or load–deflection curves of several laminates subjected to in-plane as well as bending loads are obtained. It is shown that the FE results agree well with analytical and experimental data.