Finite Element-Based Simulations of Damage in Composites

Solid finite element-based techniques are attractive for simulation of the matrix-dominated failure modes in composites. This work shows the ability of such techniques to capture the initiation and growth of matrix ply-cracks and delaminations in carbon/epoxy laminates. Three-dimensional finite element models for open-hole tensile test articles are developed. Such models account for the micro-mechanical damage in the matrix through nonlinear interlaminar stress-strain relations. Stressbased and fracture mechanics-based failure criteria are used to predict the matrix-dominated failures. Material stiffness loss consistent with the failure criteria is implemented in the 3D solid finite element-based failure models for simulation of the matrix-ply cracks. Initial damage and a predefined path are not required. Also, cohesive-zone models are used to capture delamination. Damage initiation and growth simulations for the open-hole tensile articles are accomplished. Damage sequence, surface strains and failure loads are verified with tests.