A molecular dynamics investigation of rapid fracture mechanics

Abstract

Dynamic fracture is investigated for two-dimensional notched solids under tension using million atom systems. Brittle material and ductile material are modeled through the choice of interatomic potential functions which are Lennard-Jones and embedded-atom potentials, respectively. Numerical calculations are carried out on the IBN SP parallel computer and molecular dynamics is implemented using a spatial-decomposition algorithm. Many recent laboratory findings occur in our simulation experiments. A detailed comparison between laboratory and computer experiments is presented, and microscopic processes are identified. For rapid brittle fracture, the dynamic instability of the crack growth is observed as the crack velocity approaches one-third of the Rayleigh wave speed. At higher crack velocity, the crack either follows a wavy path or branches and the anisotropy due to the large deformation at the crack tip plays the governing role in determining the crack path. Limited comparison of rapid brittle fracture process with the rapid ductile fracture process is made. © 1997 Elsevier Science Ltd.