Molecular Dynamics Simulation on Nano-Machining of Single Crystal Copper with a Void

Abstract

Nowadays, the ultra-precision machining with single diamond tools can remove materials at nanometer scale, which has been used to produce surface with high quality finishing. As far as the conventional finite-element method becomes impossible for numerical analysis, as an alternative, molecular dynamics (MD) method is significantly implemented in the field of nano-machining process to investigate cutting mechanism. Although it is well known that even the purest real material contains a large number of defects within its crystal structure, in conventional MD simulation of nano-cutting process the workpiece is assumed as a perfect single crystal. So, there is a need to check the effect of defect inclusion in the workpiece on nano-machining process.

In this chapter molecular dynamics simulations of the nano-metric cutting on single-crystal copper were performed with the embedded atom method (EAM) potential. To investigate the effect of the void on the workpiece machining characteristic, a comparison was done between perfect single crystal and a single crystal with a certain void. The numerical results reveal that the void inclusion can decrease the tool forces and affect the chip formation mechanism. Also, in defected workpiece, the value of pressurized atoms is decreased in front of the tool tip. In addition, the plastic zone becomes larger in a workpiece with a void defect compared to a pure workpiece, which can affect the surface integrity. Finally, results show that the internal surface of a void that is positioned under the machined surface is crumpled due to high compressive hydrostatic pressure.