  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.
