Comparison of numerical and analytical cohesive zone length models in the delamination of composite laminates

In recent decades, the use of composite materials in engineering structures has increased dramatically.. Therefore, it is necessary to understand the structure and mechanisms of damage to these materials. Among the most common damages in composite materials, delamination is one of the catastrophic failure modes. Cohesive zone model is one of the appropriate tools for analyzing the phenomenon of delamination in the laminated composites. The cohesive zone model analyzes the delamination by tracking the damage from its onset to its evolution. In the cohesive zone model, the area behind the crack tip, where the cohesive forces are active, is of great importance. This zone is directly affected by loading mode, fracture energy and cohesive strength, active elastic modulus, and structural geometry. Many models have been proposed to estimate the length of the cohesive zone. In this study, the length of the cohesive zone in first and second pure mode was obtained by using finite element analysis in Abaqus software. The results of the simulation were compared with the analytical models for estimating the length of the cohesive zone. It was observed a more accurate estimate of the cohesive zone length in models that consider the material type and effect of structural geometry.