On the distribution of delamination in composite structures and compressive strength prediction for laminates with embedded delaminations

In this study, large numbers of aircraft composite structures were inspected, and the distribution of delamination sizes and though thickness positions in the composite laminates are investigated. An experiment is conducted to probe into the influence of delamination sizes and through thickness positions on the compressive strengths of laminates with single embedded circular delamination, with the most dangerous delamination sizes and positions defined from the distribution. Furthermore, a shell model is established for compressive strength prediction, with delamination propagation assessed using a mixed mode criterion. The finite element (FE) prediction comes out to be in good agreement with the experimental measurements, for the predicted compressive strengths stand within 10% error of experimental results. It was observed that the compressive strength was highly influenced by the delamination size, while the through thickness position of delamination did not have significant effect on the compressive strength.