Theory and molecular dynamics modeling of spall fracture in liquids

Abstract

The model of fracture of liquid under tension is developed. It is based on the “nucleation-and-growth” approach introduced initially by D. R. Curran et al. Phys. Rep. 147, 253 1987. The model derives the kinetics of fracture at mesoscale from the kinetics of elementary processes of void nucleation and growth in metastable liquid. The kinetics of nucleation and growth of voids in highly metastable liquid is studied in molecular dynamics MD simulations with the Lennard-Jones interatomic potential. The fracture under dynamic loading is considered, when the homogeneous void nucleation is relevant. The model is applied to the estimation of the spall strength of liquid. The growth of nanometer-size voids is shown to be well described by the Rayleigh-Plesset equation. The calculations of the void size distribution by the proposed kinetic model are in agreement with the distributions obtained in the direct large-scale MD simulations. The spall strength evaluated by the model is in a good agreement with the experimental data the shock wave tests on hexane and the direct MD simulations. The correspondence between our results on nucleation rate and the predictions of the classical nucleation theory is discussed.