Three-dimensional fracture via large-scale molecular dynamics

A series of massively parallel molecular dynamics simulations with up to 35 million atoms is performed to investigate dislocation emission from a three-dimensional crack. We observe dislocation loops emitted from the crack front, both in the bulk and near the free surfaces. The sequence of dislocation emission in the process of crack blunting strongly depends on the crystallographic orientation of the crack front and differs strikingly from anything previously conjectured. This finding is essential to establish a precise dislocation emission criterion (i.e: intrinsic ductility criterion). We also find that boundary conditions and interatomic force laws have a significant effect on jogging or blunting dislocation emission modes. (C) 1998 Elsevier Science Ltd. All rights reserved.