IMPERFECTION SENSITIVITY AT DELAMINATION BUCKLING AND GROWTH

The influence of initial geometric imperfections is analysed at buckling and crack growth in compressed composite plates with delaminations present. First, initial buckling based on bifurcation theory and postbuckling is considered for initially flat laminates with appropriate crack parameters determined. For initially deflected plates, Marguerre shallow shell theory is drawn upon and by a scaling procedure pertinent results in the case of imperfections may be generated directly from those of perfect plates. The method is based on the assumption of affinity between initial and postbuckling transverse deflections. In particular for inextensible buckling states, the method is exact while in more general cases estimates are obtained. Illustrations of the method and procedures are given for several representative cases and especially the associated accuracy of the method is delineated.