Numerical analysis of delamination growth in composite materials using Two Step Extension and Cohesive Zone methods

The simulation of delamination using the Finite Element Method (FEM) is a useful tool to analyze fracture mechanics. In this paper, simulations are performed by means of two different fracture mechanics models: Two Step Extension (TSEM) and Cohesive Zone (CZM) methods, using implicit and explicit solvers, respectively. TSEM is an efficient method to determine the energy release rate components GIc, GIIc and GIIIc using the experimental critical load (Pc) as input, while CZM is the most widely used method to predict crack propagation (Pc) using the critical energy release rate as input. Both methods were compared in terms of convergence performance and accuracy to represent the material behaviour and in order to investigate their validity to predict mode-I interlaminar fracture failure in unidirectional AS4/8552 carbon fibre composite laminates. Numerical simulations are compared with experimental results performed by means of Double Cantilever Beam (DCB) in order to discuss the results and to have a full visualization of this damage. Results showed a good agreement among both FEM models and experimental results