An investigation was performed to study damage accumulation in multidirectional laminated composite plates subjected to in-plane loads. Matrix cracking-induced accumulated damage in a multi-directional laminate was the primary concern. A progressive damage analysis has been developed for predicting the accumulated damage and its effect on the failure and the response of the composite plates. The development of the analysis was based on the assumption that the accumulated damage would be generated uniformly in composites under uniform in-plane loads. Hence, the free edge effect and the laminates that are prone to delamination were not considered in the analysis.
The analysis consists of three parts: constitutive modeling, damage accumulation prediction, and stress analysis. Based on the two-dimensional elasticity analysis, constitutive equations of a ply containing matrix crack-induced damage in a laminate were developed. In the failure analysis, a set of damage accumulation criteria modifying the existing failure criteria was proposed for predicting the extent of the damage in composites as a function of the applied loads. The stresses and deformations in the laminates were calculated by a nonlinear finite element method that incorporated the constitutive equations and the damage accumulation criteria.
The predictions of the model were compared with the available experimental data for laminates with and without a cutout. Overall, the predictions agreed with the data quite well.