Modelling fracture and delamination in composite laminates: Energy release rate and interface stress

This article presents an approach for modelling fracture and delamination, based on the partition of finite elements and on the energy release rate due to crack propagation in cross-ply laminates. The energy release rate is implemented within an Extended Finite Element Method (XFEM) framework. This approach is enabling the prediction of delamination propagation without pre-allocating damage zones. No element deletion techniques were used either. Mesh refinement was not needed for the propagation of cracks. Virtual testing of transverse cracks - eventually triggering delamination in cross-ply laminates - is presented to show the technique efficiency. Thus, a maximum energy release rate of 0.9kJ/m2 is found for a transverse crack within [00,900]s laminate. When maximum energy release rate is reached, delamination in the {00/900} interface is triggered. Furthermore, delamination in a composite double cantilever beam is simulated and presented in some detail. The results were compared with experimental outputs and/or by other numerical means showing an excellent correlation.