Molecular dynamic investigations of the shock pulses interaction with nanostructured free surface of a target

Abstract

We performed the molecular dynamic simulations of the high-velocity impact of thin copper impactor with copper targets with both flat and nanostructured rear surface. It is shown that the spall fracture threshold can be increased due to the presence of nanostructures on the rear surface of target. Presence of protrusions changes the stress state and provokes an intensive plastic deformation. As a result, a part of the compression pulse energy dissipates due to the plastic deformation in this surface layer. It leads to decrease of the tensile wave amplitude and, consequently, an increase of the spallation threshold in terms of the incident shock wave intensity. The threshold increase is essential if the protrusion height is about the compression pulse width, which is controlled by the impactor thickness first of all.