Combining dual domain material point method with molecular dynamics for thermodynamic nonequilibriums

Abstract

The dual domain material point method (DDMP) combined with molecular dynamics (MD) is used to simulate a material undergoing a large deformation with a high strain rate. In the simulation, the continuum scale equation of motion is solved using DDMP, while the stresses required at the material points are obtained by performing MD simulations in small domains surrounding the material points following the entire history of the material deformation without reinitialization of the MD systems; therefore the history dependence, a common feature for thermodynamically nonequilibrium systems, can be tracked accurately.Two algorithms are introduced to avoid distortion of the MD domains and to ensure consistence in the energy density between the MD and macroscopic calculations. As an example, a hyper-velocity impact problem is simulated. The results of the combined DDMP–MD calculations are compared to a pure MD simulation. The method of the combined simulation is applicable to macroscopic systems, although the size of the simulation domain is only a few hundred nanometers in this example because of the limitation of the pure MD simulation.