A NONLINEAR-DISCRETE MODEL OF DYNAMIC FRACTURE INSTABILITY

Molecular-dynamics simulations of dynamic fracture show that local she ar deformation at the crack tip increases, and local potential energy builds up, eventually triggering dislocation emission - the instabilit y that leads to crack branching Neither the build-up nor the instabili ty can be predicted by linear-continuum theories. We propose a simple nonlinear-discrete model, which demonstrates that the excitation of no nlinear modes generates this instability. (C) 1997 Published by Elsevi er Science B.V.