Mixed-Mode Fracture in Plastically Deforming Materials

Abstract

A finite element method was developed for evaluating an angled crack in a thin plate. In the spirit of the Dugdale and Barenbaltt damage zone models, the method superposes cohesive stresses in a damage zone onto a linear elastic fracture analysis. The method uses incremental changes in the boundary conditions along the damage zone to model loss in stiffness due to yielding and stable crack growth. A crack tip opening displacement criterion is used for predicting stable crack growth and unstable crack growth. The resulting nonlinear analysis is used to predict the applied loads at failure. Numerical results compared favorably with experimental values.