Simulation of stable tearing crack growth events using the cohesive zone model approach

A cohesive zone model (CZM) approach is applied to simulate Mode I and mixed-mode I/II stable tearing crack growth events in Arcan specimens made of 2024-T3 aluminum alloy. The material is treated as elastic–plastic following the J2 flow theory of plasticity, and the triangular cohesive law is employed to describe the traction-separation relation in the cohesive zone ahead of the crack front. Simulations are carried out using the 3D finite element method. CZM parameter values are chosen based on considerations of values suggested in the literature and by matching simulation predictions with experimental data of the load–crack extension curve for a Mode I stable tearing crack growth event. With the same set of CZM parameter values, simulations are performed for mixed-mode I/II stable tearing crack growth events. A good agreement is reached between simulation predictions of the load–crack extension curve and experimental results. To connect with a simulation approach based on the crack tip opening displacement (CTOD) at a fixed distance behind the current crack front, the variation of CTOD with crack extension is examined under both Mode I and Mode I/II conditions. It is found that CZM simulation predictions of the CTOD variation with crack extension agree well with experimental measurements. The results of this study suggest that CZM based simulations can predict the critical CTOD value which, in CTOD based simulations, is used as an input and is conventionally obtained from experimental measurements. The findings of the current study demonstrate the applicability of the CZM approach in mixed-mode stable tearing simulations and establish a connection between the CTOD and CZM based simulation approaches.