We investigate, by molecular dynamics simulation, the generic features associated with the dynamic compaction of metallic nano-foams at very high strain rates. A universal feature of the dynamic compaction process is revealed as composed of two distinct regions: a growing crushed region and a leading fluid precursor. The crushed region has a density lower than the solid material and gradually grows thicker in time by {\it snowplowing}. The trapped fluid precursor is created by ablation and/or melting of the foam filaments and the subsequent confinement of the hot atoms in a region comparable to the filament length of the foam. Quantitative characterization of nano-foam compaction dynamics is presented and the compacted form equation-of-state is discussed. We argue that high-energy foam crushing is not a shock phenomenon even though both share the snowplow feature.
@article{arxiv.1102.3718,
title = {Compaction dynamics of metallic nano-foams: A molecular dynamics simulation study},
author = {M. A. Duchaineau and J. B. Elliott and A. V. Hamza and T. Dittrich and T. Diaz de la Rubia and Farid F. Abraham},
journal= {arXiv preprint arXiv:1102.3718},
year = {2011}
}