Effect of nano-void position on surface integrity in nanomachining of single crystal copper

In this paper, molecular dynamics simulations were performed to study the effect of nano-size voids in different locations relative to the surface on nanomachining characteristics and surface integrity. Using EAM potential, MD simulations were performed with two approaches: material removal and relaxation of the work material, to find a low defect permanent configuration after the rigid tool has traversed the machined area. Results show that high hydrostatic pressure induced by tool edge diffuses atoms into the void during the machining process. Investigation of residual stress for subsurface void workpiece represents that higher compressive stress remains in the surface due to the tendency of void for spring back. Besides, in the nanomachining process, surface atoms are greatly disordered and dislocation loops glide deep into substrate atoms. After relaxation, if void pitting contains no other atoms, the machined surface is reorganised as FCC lattice similar to a pure workpiece.