Structure-property responses of bio-inspired synthetic foams at low and high strain rates

Abstract Various aluminum foams were fabricated with a structure comparable to the Terrapene carolina (box turtle) shell hierarchy as a synthetic means of attaining the lightweight, yet impact-resistive, nature of the biological counterpart. Each foam was constructed from a single aluminum alloy but with different morphologies and foam densities. By borrowing from the sophistication of biological design, the aluminum foams were shown to exhibit robust mechanical performance. High strain rate experimentation, via split Hopkinson pressure bar, was utilized to reveal the strain rate sensitivity of the foams as well as a metric to compare impact performance. The structure-property relations, necessary for accurate material modeling, were also characterized by way of optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and nanoindentation tests. The robust varying mechanical performance was attributed to the biologically inspired materials design.