Modeling Compression Failure of laminated Composites Containing Multiple Through-the-Width Delaminations

An analytical and experimental investigation was performed to study the compression response of laminated composites containing multiple delaminations. It was of particular interest to determine the effects of delaminations on the residual stiffness and strength of delaminated composite structures and on the ability of the structures to sustain compression. An analytical model was developed for simulating the compression re sponse, from initial loading to final collapse, of laminated composites containing multiple through-the-width delaminations. The model is comprised of three parts: a stress analysis, a failure analysis, and a contact analysis. The stress analysis was developed for simulating the buckling and post-buckling response of the structures, the failure analysis was pro posed for predicting delamination growth and fiber-matrix failure, and the contact analysis was developed for analyzing delamination interface condition during loading. A nonlinear finite element code based on the updated Lagrangian formulation was developed for the model. Extensive experiments on T300/976 graphite/epoxy composites were also per formed to verify the model. Laminates with one or two delaminations were tested. Good agreements were obtained between the predictions and the test data from the initial loading to the final collapse of the specimens. Numerical simulations were also performed to dem onstrate the effect of size, location, and distribution of multiple delaminations on the com pression response of composites.