||CMES: Computer Modeling in Engineering & Sciences, Vol. 2, No. 2, pp. 143-154, 2001
||Full length paper in PDF format. Size = 943,698 bytes
||Molecular Dynamics, Brittle Fracture, Crack Propagation, Grain Boundary ,$\alpha$-Fe.
||In this paper, we present a classical molecular dynamics algorithm and its implementation on Cray C90 and Fujitsu VPP700. The characters of this algorithm 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 Cray C90 and a 32-node VPP700, and measurements of computational performance are reported. Then, we examine the interaction between a crack propagating and a tilt grain boundary under uniaxial tension using this computer program. The Johnson potential for$\alpha$-Fe is used in these simulations. A structural transition from bcc to hcp induced by hydrostatic stress and brittle crack propagation are observed in a system including a crack whose direction is  in the (101) plane. In a system including both the crack and a (112) grain boundary which is symmetric and stable, not only the phase transition but also crack propagation is restrained by the grain boundary. In a system including both the crack and a (111) grain boundary which is asymmetric and unstable, intergranular crack propagation occurs after the crack tip reaches the grain boundary.