Failure of Delaminated Carbon/Epoxy Composite Plates under Compression

Abstract

The purpose of this work is to study the buckling loads, buckling modes, postbuckling behavior, and critical loads of delamination growth for delaminated unidirectional carbon/epoxy composites. Nonlinear buckling analysis, which is a finite-element method including contact elements to prevent the overlapping situation, was applied to predict the delamination buckling loads. In order to predict the delamination growth loads, the total strain-energy release rate criterion, the strain-energy release rate component criterion, and the inerlaminar stress criterion were used in the postbuckling analysis. Experimental results were also provided to compare with the prediction. The results indicate that nonlinear buckling analysis has very good agreement on the buckling loads with the experiments except for the global buckling case. For global buckling mode, the buckling loads are suggested to represent the failure loads of delaminated composites, and postbuckling analysis may not be necessary. For mixed and local buckling modes, the postbuckling behavior is in the mixed mode, and the failure of the delaminated composite is due to the growth of delamination. The errors of the three different criteria in predicting delamination growth loads are from 10% to 22% for different cases.