Prediction of Cohesive Zone Length and Accurate Numerical Simulation of Delamination under Mixed-mode Loading

This article presents an approach to accurately predict the Length of Cohesive Zone (LCZ) and model delamination under mixed-mode loading. A novel expression for estimating the cohesive zone length for the structure subjected to mixed mode delamination is proposed. The proposed expression of LCZ is validated for various structural configurations like mixed-mode delamination specimen, ply-drop, and L-bend. Besides, the effect of maximum interfacial strength and element size is also investigated. A modified embedded cohesive zone model based on cohesive surface modeling is suggested to predict intralaminar and interlaminar failures in ply-drop and L-bend structures. The cohesive surfaces are inserted in 90o plies to account for the matrix cracking and along the adjacent 0o plies to model interlaminar delamination. The delamination accompanied by matrix cracking, resulting in crack kinking and migration, is predicted. The predicted numerical results are in very good agreement with the experimental results available in the literature. A fine discretization of the mesh is necessary along the cohesive zone length for the precise estimation of various energy dissipation mechanisms. Thus, the present methodology aids in the mesh design by calculating LCZ and accurately predicting the structure's failure response under mixed-mode delamination.