Compaction Dynamics Of Metallic Nano-Foams

TL;DR

This study uses molecular dynamics simulations to analyze the high strain rate compaction of metallic nano-foams, revealing a universal process involving a crushed region and a fluid precursor, with implications for understanding foam behavior.

Contribution

It introduces a detailed molecular dynamics analysis of nano-foam compaction, highlighting the distinct crushed and fluid regions and challenging shock-based interpretations.

Findings

Identification of a two-region compaction process: crushed and fluid precursor.

Quantitative characterization of nano-foam compaction dynamics.

High-energy foam crushing differs from shock phenomena despite snowplow features.

Abstract

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 "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.