Hypervelocity-impact phenomena via molecular dynamics

Novel molecular-dynamics calculations have been carried out for a hypervelocity impact of a sphere of 683 atoms (a central atom surrounded by 23 coordination shells) hitting a rectangular plate composed of 8000 atoms (five close-packed planes thick). The ratio of the sphere diameter to the plate thickness was chosen to be approximately 2.4, with the velocity of the sphere chosen such that its kinetic energy was roughly 25 times its binding energy, relative to the bottom of the potential well. Under these conditions, the debris cloud generated by the ball after it penetrates the wall is composed mostly of vaporized material. These microscopic results scale hydrodynamically to macroscopic experiments of a lead sphere hitting a lead plate at $u_p$=6.6 km/s. There are striking similarities between these atomistic calculations and continuum hydrodynamics simulations, as well as notable differences.