An analytical and experimental investigation was performed to study the damage in laminated composites containing an open hole and subjected to compressive loading. A progressive damage model was developed during the investigation to predict the extent and the failure modes of the internal damage in the laminates as a function of the applied load and to simulate the in-plane response of the laminates from initial loading to final collapse. The model consists of a stress analysis and a failure analysis. Stresses and strains inside the laminates were calculated by a nonlinear finite element analysis which is based on finite deformation theory with consideration of material and geometric nonlinearities. The types and extent of damage in the material were predicted by a failure analysis which includes a set of proposed failure criteria and material degradation models.

Extensive experiments were also conducted to study the compression-induced failure mechanisms of notched laminates and to generate data for verifying the proposed model. T300/976 graphite/epoxy material was selected for the tests. X-radiographs were used to examine internal damage of the composites, and an extensometer was used to record the deformation of the laminates during loading. Excellent agreement was found between the test results and predictions based on the model.

A computer code was developed based on the model. The code was used to make parametric studies which help to explain some of the physical phenomena observed.