Finite element interface models for the delamination analysis of laminated composites: mechanical and computational issues

The nite element analysis of delamination in laminated composites is addressed using interface elements and an interface damage law. The principles of linear elastic fracture mechanics are indirectly used by equating, in the case of single-mode delamination, the area underneath the traction=relative displacement curve to the critical energy release rate of the mode under examination. For mixed-mode delamination an interaction model is used which can ful l various fracture criteria proposed in the literature. It is then shown that the model can be recast in the framework of a more general damage mechanics theory. Numerical results are presented for the analyses of a double cantilever beam specimen and for a problem involving multiple delamination for which comparisons are made with experimental results. Issues related with the numerical solution of the non-linear problem of the delamination are discussed, such as the in uence of the interface strength on the convergence properties and the nal results, the optimal choice of the iterative matrix in the predictor and the number of integration points in the interface elements