Nonlinear buckling analysis of damaged laminated composite plates

An updated Lagrangian-based nonlinear finite element method is developed to study the buckling behavior of damaged laminated composite plates under uniaxial compression. In this study, material imperfections are treated as existing static damage and a continuum damage mechanics-based approach is used to model such imperfections. The laminated plate is modeled as a set of elementary layers bonded together by matrix-rich elastic interface. This allows to model different modes of damage present at both elementary ply level and interply interface separately. A layerwise plate model is used to model both elementary ply and interface layers of the laminate. The effect of different forms of existing static damage on the limit point loads and the corresponding displacements of laminated plates are studied. It is observed that for the chosen modes and size of the damaged regions, the limit point load does not change much as compared to the undamaged plate. However, the deformed shapes show significant changes and some very interesting phenomena like local wrinkling behaviour of the damaged region is observed. The effect of ply orientation along with different modes of damage on the limit points and the corresponding deformed shapes of laminated plates are also discussed.