Compaction and plasticity in nanofoams induced by shock waves: A molecular dynamics study

Abstract

Shock waves are produced in Al nanofoams by a piston moving with velocity Up. They induce plastic activity in the ligaments before eventually the foam structure is crushed and a compact material results. We demonstrate dislocation formation in the foams and correlate it with the velocity and stress profiles in the shock wave. The profiles exhibit a 3-wave structure indicating 3 wave regimes: elastic precursor, plastic activity in the ligaments, and foam crushing. The shock wave velocity V follows well macroscopic predictions, V ∞ Up. The length of the non-collapsed part of the foam is well described by an analytical compaction model.