Cohesive zone representation of crack and void growth in single crystal nickel via molecular dynamics simulation

Abstract

Pre-existing center crack and void growth in single crystal nickel under Mode I loading are investigated by introducing a cohesive zone model (CZM) based on molecular dynamics (MD) simulation. The microstructural evolution and stress distribution during crack and void growth are analyzed as are the associated mechanical properties. The results indicate that the crack and void have different fracture mechanisms. Crack-tip blunting occurs due to the [110] super-dislocations emission during crack growth, while for void growth the primary micro-mechanism is the formation of stacking faults, which result in the different growth rates, opening displacements, and stress states. Based on the calculation of the CZM, the crack has a greater growth speed and opening displacement, but a lower tensile stress and fracture strain than the void under the same loading conditions, and the high stress is accompanied by microstructural evolution during crack and void growth.