This grant is to provide 50 CRAY hours Supercomputer time on Class VI computer to conduct modelling studies of the process of crack initiaiton and rapid crack propagation in semiductile and ductile materials where the inelastic material response and material inertia affect the load transfer characteristics. The studies are intended to provide detailed quantitative descriptions of the stress and deformation fields in the near-tip region and to relate these near-tip descriptions to the overall structural behavior. The computational simulation study requires the computing power of a Class VI computer. The computational results will help to establish criteria for crack initiation, propagation, and arrest under dynamic conditions.