Atomic Scale Studies of Spall Behavior in Single Crystal Cu

Abstract

The micromechanisms related to ductile failure during dynamic loading of single crystal Cu are investigated using large-scale molecular dynamics (MD) simulations. Void nucleation, growth, and coalescence is studied for a single-crystal Cu system under conditions of impact of a shock piston with a velocity of 500 m/s. The compressive shock wave generated reflects from the rear surface as a tensile wave and meets with the tail of the shock wave at the spall plane. The interaction results in a triaxial tensile stress state that nucleates a large number of voids at the spall plane. MD simulations suggest that voids nucleate at intersections of stacking faults generated in the spall plane under the triaxial tensile stress conditions. Two stages of void growth are observed during dynamic failure of single-crystal Cu: Stage I corresponds to fast nucleation and growth of the nucleated voids and Stage II corresponds to coalescence and slow growth of the voids.