Prediction of failure of strength differential materials by using cohesive zone model

Abstract

Cohesive zone model has been widely used to predict and analyze the behavior on the interface area when load is applied. A constitutive equation for the cohesive zone model describes the relationship between traction and effective separation. The phenomena for crack such as crack initiation, propagation and final fracture can be explained theoretically with the constitutive equation. Due to the limitation of using the default models in a commercial software, ABAQUS UMAT (User MATerial) interface is used to implement Tvergaard’s 1990 debonding model. Hill48 yield model is implemented to describe the behavior of tensile anisotropy. The research was extended to model the strength difference between tensile and compressive behaviors. Various metals generally show the plastically asymmetric behavior, which shows strong strength differential (SD) effect with distortion hardening and it is not able to be predicted by Hill48 yield function. The yield function proposed by Yoon et al. (2014) was implemented to predict the debonding behavior of cohesive layer more exactly for the asymmetric behavior of the metals.