Remarks on dynamic cohesive fracture under static pre-stress — with a comparison to finite fracture mechanics

Abstract

The role of inertia effects during crack formation under non-singular static pre-stress is investigated by utilizing a linear softening cohesive zone model. In case of a 1D tensile bar, the closed-form solution shows that during the finite time of decohesion about one third of the released strain energy is converted into kinetic energy. In case of crack initiation from a circular hole in a 2D plate under remote tension or compression, results from dynamic finite element analyses utilizing the same cohesive zone model are compared with predictions from finite fracture mechanics which assumes the spontaneous formation of a finite crack increment. While both methods capture the overall critical load for crack initiation at the hole well, the highly transient process of crack nucleation (not accounted for by finite fracture mechanics) is resolved by the numerical cohesive zone model analyses and displays a complex dependence on the hole radius.