A multiscale framework for high-velocity impact process with combined material point method and molecular dynamics

The equation of state (EOS) plays an important role in high-velocity impact process since phase transformation, melting, and even vaporization may happen under such extreme loading conditions. It is desired to adopt an accurate EOS covering a large range of points in the phase space. This paper proposes a combined molecular dynamics and material point method approach to simulate the high-velocity impact process. The EOS data are first obtained from a series of molecular dynamics computations, and the parameters are fitted. Then the EOS parameters are adopted in the material point method simulation to model the impact process. Simulation results show that the fitted EOS can be very accurate compared to experimental results. The shape of the debris cloud obtained by our multiscale method agrees well with that of the experiments. An empirical equation is also proposed to predict the fraction of melting material in the high-velocity impact process.