Postbuckling Behaviors of Composite Panels with Multiple Delaminations

Abstract

Compressive behaviors of composite panels with through-width, equal- size, equally-spaced multiple delaminations are investigated analytically. An analytical method is formulated on the basis of the Rayleigh-Ritz approximation technique. Contact problem on the delaminated surfaces is considered by the introduction of a constraint, which restricts a relative out-of-plane displacement and a relative slope between the upper and lower portions at a contact point. The postbuckling paths of delaminated panels are solved numerically and the results are compared with the experimental results. If appro priate initial imperfections are assumed, the analytical results can explain well the be haviors of the delaminated panels which are observed in the compressive experiment. The results of the postbuckling analysis indicate that the simplified buckling analysis, where the opening of the delamination is not considered, is sufficient to estimate the buckling load. A method to estimate a total energy release rate is also proposed.