A method based on singularity theory to predict edge delamination of laminates

Delamination starting from a stress free edge is the main mode of failure o f cross-ply laminates. The analysis of singularities and resulting stress c oncentrations at interfaces along these edges are not sufficient to provide a satisfying model of onset mechanisms. In particular, the model is by far less sensitive to the layers thickness than observed in traction experimen ts. A refined asymptotic process is proposed which takes into account the e xistence of surface flaws (micro-cracks or notches). Numerical results prov e that this model is much more in agreement with the experiments. Moreover, the knowledge of the interface toughness, in addition with the experiments , allows to estimate a characteristic fracture length, a kind of process zo ne. It is a material property and in a first approximation it arises to be of the same order of magnitude than the characteristic inhomogeneity length of the components, i.e. the fibers diameter.