Fracture simulations via large-scale nonequilibrium molecular dynamics

We describe the historical development of large-scale nonequilibrium molecular-dynamics (NEMD) computer simulations of fracture at Los Alamos. We have found that dynamic crack propagation leads to energy buildup that seeds instabilities, such as dislocation emission and branching. Recent three-dimensional simulations have shed light on ductile fracture mechanisms, including sequences of dislocation emission in various modes that are strikingly different from anything previously conjectured. The future for constitutive modeling, based on observations of dynamical features in such NEMD simulations is quite bright, and one such example is discussed.