An experimental evaluation of crack face energy dissipation

This paper uses Lock-in dissipative thermography to address the question of plasticity induced crack tip closure. Three different specimen configurations were examined and it was found that there were two regions that dissipated energy. A small region directly adjacent to the crack tip, where the dissipated energy is directly related to crack tip plasticity, and a region away from the crack tip where the faces of the crack were rubbing. Between these two regions there was no dissipated energy. It was also found that the stress field behind the crack was out of phase with respect to the global loading.