It was recalled that molecular dynamics simulations of dynamic fracture showed that local shear deformation at a crack tip increased, and the local potential energy built up, to trigger dislocation emission; an instability that led to crack branching. Neither the build-up nor the instability could be predicted by linear continuum theories. A simple non-linear discrete model was proposed here which demonstrated that the excitation of non-linear modes generated this instability.

A Non-Linear Discrete Model of Dynamic Fracture Instability. S.J.Zhou, N.Grnbech-Jensen, A.R.Bishop, P.S.Lomdahl, B.L.Holian: Physics Letters A, 1997, 232[3-4], 183-8