ATOMISTIC SIMULATIONS OF PLASTICITY AND FRACTURE IN NANOCRYSTALLINE COPPER UNDER HIGH STRAIN RATES
3D molecular dynamics calculations of plasticity and fracture in nanocrystalline copper under high strain rate are carried out. Grain boundary sliding and dislocation motion are observed. Flow stress dependence on grain size is obtained. Three general properties of spall process are considered: existences of sites of stress concentration, two step process of microcrack formation and stochastic character of microcrack formation. Spell strength dependences on grain size and on strain rate are obtained.