Numerical investigation of the effects of operating parameters in the vibration assisted nano impact machining of single crystalline silicon by loose abrasive using molecular dynamics simulation

Abstract

In this paper, the large-scale atomic/molecular massively parallel simulator (LAMMPS) is used to perform three-dimensional molecular dynamics simulations (MDS) to model a novel nanomachining process (VANILA), in which an atomic force microscope (AFM) is used as a platform and the nano abrasives are injected in the slurry between the silicon workpiece and the vibrating AFM probe. The vibration of the AFM probe generates kinetic energy for the abrasives to impact the workpiece and consequently results in nanoscale material removal. The range of the impact speed is from 100 m/s to 200 m/s, which is the theoretically calculated impact speed. The diameter of the diamond abrasive is kept constant at 40 Å. Tersoff many-body potential is used to calculate the interatomic forces between the Si-Si atoms and Morse potential is used to compute the Si-diamond interactions. The position and velocity of all atoms are computed using the Velocity-Verlet algorithm. The effects of the operating parameters (impact speed, impact angle, and operating temperature) on the depth and width of generated nanocavities along with the impact-induced phase transformation in the VANILA process are investigated. The open visualization tool (OVITO) is used to postprocess and visualize the 3D MDS results. The simulation results show that the operating parameters have substantial influence on the depth and width of the generated nanocavities and phase transformation is clearly observed. The relations between nanocavity depth and width and operating parameters are established using multilinear regression technique in MATLAB per the simulation results.