Buckling and postbuckling behavior of composite cross-ply laminates with multiple delaminations

In this study, buckling and postbuckling analysis was conducted for the com posite cross-ply laminates with multiple delaminations under compressive lo ading. The geometries of multiple delaminations are a one-dimensional throu gh-the-width type and a two-dimensional embedded circular type. In a nonlin ear finite element formulation, the updated Lagrangian description and the modified are-length method were adopted. For a finite element modeling of c omposite laminates, the eight-node degenerated shell element was used. To a void overlapping between delaminated areas, the contact node pair was defin ed by virtual beam element. Numerical results showed that multiple delamina tions lower buckling loads and load carrying capacities in the postbuckling region. The buckling load varies with the projected area of the delaminati ons, However, the geometry of multiple delaminations has an influence on th e postbuckling behavior. The load carrying capacity differed with the distr ibution type due to the local reduction of bending stiffness and the contac t behavior of the sublaminates. (C) 1999 Elsevier Science Ltd. All rights r eserved.