Molecular dynamics simulation of dislocation evolution and surface mechanical properties on polycrystalline copper

During the nanofabrication process of polycrystalline materials, the interactions of dislocations in material determine the evolution of subsurface defects. In this paper, the molecular dynamics simulation models of nanocutting polycrystalline copper, which is used to study the relationship between the crystal structure and the cutting force during the cutting process, were established, and the transformation process between grain boundaries and dislocations was studied to get the effects of grain boundary on dislocation slip and stress conduction. The results show that there are obvious rules between cutting force and cutting process and grain boundaries can prevent dislocation slip and shielding stress conduction. The influence of different cutting parameters on the evolution of subsurface defects of workpiece was further analyzed. Finally, the nanoindentation simulations and experiments were carried out to study the influence of cutting parameters on surface mechanical properties of workpiece. It is found that to some extent, the surface hardening effect of the workpiece is remarkable with the cutting depth increase.