Portrait of a crack: Rapid fracture mechanics using parallel molecular dynamics

Simulations of up to 100 million and more atoms were used for the fracture analysis of two- and three-dimensional notched solids. In parallel simulations of the rapid brittle fracture of rare-gas films and solid slabs, dynamic instability of the crack tip was an intriguing phenomenon as it approaches a certain fraction of the Rayleigh speed. For 2D fracture simulation, crack surface roughening was identified as the onset of an intrinsic dynamic instability of the brittle fracture process. For 3D simulation, the roughening extends in depth as a one-dimensional step which is a few atom diameters wide and occurs when the crack-tip velocity equals about 0.33 of the Rayleigh sound speed for the rare-gas solid.