Abstract
The author proposed a new criterion of micro-crack nucleation, which was deduced theoretically by shock wave theory, based on a new concept whereby micro-crack nucleation is caused by a jump in the wave velocity along the intersection line between two different stationary discontinuity bands characterized by the vanishing velocity of an acceleration wave. Successively, in order to consider the crystal orientation dependence of the ductile fracture progress, algorithm of the proposed criterion was incorporated into the finite element crystal plasticity model. In the present paper, the new micro-crack evolution equations are derived based on the previously proposed evolution equation. The new evolution equation deduces the strain jump being infinite within finite time which corresponds occurrence of the displacement jump: macro-crack/void. Simulations of ductile fracture progress of FCC single crystal notched plates with different crystal orientations to the loading direction and also qualitative comparisons of simulated results with experimental observations are performed. Based on the simulations and the new evolution equations it is concluded that the strain gradient dominates the ductile fracture progress from micro-crack nucleation to macro-crack growth and fracture/collapse.
