Multiscale simulations of nanoindentation and nanoscratch of single crystal copper

In this paper, a three-dimensional multiscale method coupling molecular dynamics (MD) and finite element (FE) analysis has been employed to study nanoindentation and nanoscratch processes of copper thin film. During the nanoindentation process, no discontinuities can be observed in the displacement gradient, which demonstrates a seamless coupling between MD and FE regions. The multiscale model of nanoindentation is further validated by the fact that the load-depth curves obtained from both multiscale and full MD simulations match each other reasonably well. The nanoindentation results using multiscale model are also compared with those using part MD model to elucidate the advantages of multiscale method. The multiscale simulation results of nanoindentation show that the indentation velocity has a great effect on the load-depth curve and hardness of copper. The continuity of displacement field during the nanoscratch also demonstrates a seamless information exchange between MD and FE regions. The deformation of substrate and forces in the nanoscratch process are also investigated using the multiscale method. The multiscale method can greatly expand the system size to be explored without significant increase in computational cost.