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