Molecular dynamics simulation of crack propagation in polycrystalline material

In this paper, we present a classical molecular dynamics algorithm and its implementation on Gray C90 and Fujitsu VPP700. The characters of this algor ithm consist in a grid based on the block division of the atomic system and a neighbor list based on the use of a short range potential. The computer program is used for large scale simulations on a Gray C90 and a 32-node VPP 700, and measurements of computational performance are reported. Then, we e xamine the interaction between a crack propagating and a tilt grain boundar y under uniaxial tension using this computer program. The Johnson potential for alpha -Fe is used in these simulations. A structural transition from b cc to hcp induced by hydrostatic stress and brittle crack propagation are o bserved in a system including a crack whose direction is [010] in the (101) plane. In a system including both the crack and a [110](112) grain boundar y which is symmetric and stable, not only the phase transition but also cra ck propagation is restrained by the grain boundary. In a system including b oth the crack and a [1 1 0](1 1 1) grain boundary which is asymmetric and u nstable, intergranular crack propagation occurs after the crack tip reaches the grain boundary.