Compaction dynamics of metallic nano-foams: A molecular dynamics simulation study

TL;DR

This study uses molecular dynamics simulations to analyze the high-strain-rate compaction process of metallic nano-foams, revealing universal features like a crushed region and fluid precursor, and discussing the equation-of-state of the compacted material.

Contribution

It provides a detailed molecular dynamics analysis of nano-foam compaction, identifying universal features and distinguishing it from shock phenomena.

Findings

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

Quantitative characterization of nano-foam compaction dynamics.

Discussion of the equation-of-state for the compacted nano-foam.

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 {\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.