Phase field crystal model simulation of transonic dislocations and mode Ⅱ crack propagation

Abstract

The mobility law of an edge dislocation under high strain rates is studied using the phase field crystal model. The transonic dislocation previously accessible only by molecular dynamics method is observed. It is found that there exists a threshold shear stress associated with the dislocation velocity transition from the subsonic to the transonic one. Upon reaching such threshold, stress at the dislocation rear decreases, emitting a decaying shear wave and establishing a dynamic equilibrium between driving forces and energy dissipation. Further, effects of strain rates and crystallographic orientations on crack propagation are explored. At presence of a void, the void located at a position deviating an angle of 45° from the crack plane is the most likely to merge with the crack. Two mechanisms, i.e., new void or crack mediated growth and attraction through directional growth, contribute to the merging.