A systematic molecular dynamics study of the competition between crack growth and dislocation emission from a crack tip was performed. Two types of boundary condition were adopted: planar extension, or boundary displacements according to the anisotropic mode-I asymptotic continuum solution. The effects of temperature, loading rate, crystal orientation, sharpness of crack tip, atomic potential and system size were investigated. Depending upon the crystal orientation, dislocation nucleation could be driven either by the strain or by concerted fluctuations at the crack tip. In the latter case, the crystal orientation and the temperature had the greatest influence upon the process of dislocation nucleation.

Molecular Dynamics Study of Dislocation Nucleation from a Crack Tip. B.Hess, B.J.Thijsse, E.Van der Giessen: Physical Review B, 2005, 71[5], 054111 (10pp)