A mesoscale investigation of strain rate effect on dynamic deformation of single-crystal copper

A combined finite element (FE) simulation and discrete dislocation dynamics (DD) approach has been developed in this paper to investigate the dynamic deformation of single-crystal copper at mesoscale. The DD code yields the plastic strain based on the slip of dislocations and serves as a substitute for the 3D constitutive form used in the usual FE computation, which is implemented into ABAQUS/Standard with a user-defined material subroutine. On the other hand, the FE code computes the displacement and stress field during the dynamic deformation. The loading rate effects on the yield stress and the deformation patterning of single-crystal copper are investigated. With the increasing of strain rate, the yield stress of single-crystal copper increases rapidly. A critical strain rate exists in each single-crystal copper block for the given size and dislocation sources, below which the yield stress is relatively insensitive to the strain rate. The dislocation patterning changes from non-uniform to uniform under high-strain-rate. The shear stresses in the bands are higher than that in the neighboring regions, which are formed shear bands in the crystal. The band width increases with the strain rate, which often take places where the damage occurs.