Effect of Delamination on Buckling Behavior of Quasi-Isotropic Laminates

A finite element modeling is presented to study the effect of delamination on the buckling behavior of quasi-isotropic laminates. The effects of delamination on the buckling and postbuckling behavior of graphite/epoxy composite laminates are investigated for various delamination sizes, stacking sequence and boundary conditions. Three different possible modes of instability are identified at the critical load, which is global, mixed, and local buckling mode. The buckling load and postbuckling behavior depend on the delamination buckling mode that is determined by the delamination size, stacking sequence and boundary conditions. It is found that the presence of a delamination in composite laminates may induce couplings, which have significant effects on the buckling and postbuckling behavior of composite laminates.