Superior energy dissipation mechanisms compounded within composite AA6061/H130 foam structures

Abstract

Significant demand exists for sacrificial energy absorbers which can achieve ideal mechanical performance (i.e., near-constant reaction forces) utilizing lightweight, readily available materials to simultaneously improve occupant safety and minimize vehicle mass to address growing calls to further improve efficiency in the transportation sector. A novel energy dissipation system comprised of AA6061 extrusions subjected to hybrid cutting/clamping and axially compressed H130 PVC foam, which could compound the ideal mechanical performance of each lightweight constituent component, was conceptualized and experimentally tested under quasi-static loading conditions. Since the extrusions remained intact above the blades the foam cores experienced uniform compression without in-plane deformation, leading to uniquely negligible extrusion/foam interaction effects. Extrusions with a T4 temper condition further benefited from resistance to circumferential distortion attributed to internal support from the foam cores. This behavior was in stark contrast to complementary structures subjected to a conventional axial crushing mode which experienced unstable combinations of lateral kinking, brittle lobe fracture and highly fluctuating reaction forces due to inconsistent interaction effects. The average TEA and energy absorbing effectiveness factor (EAEF) improved by 13 % and 38 %, respectively, for the composite structures subjected to novel compounded cutting/clamping compared to the traditional crushing mode, quantifying the enhancements over the current state-of-the-art. An analytical modeling procedure which could accurately (> 5 % error) replicate the newly observed, compounded force/displacement responses was derived and utilized in a parametric study identifying maximizing extrusion diameter and minimizing wall thickness and/or foam density as effective approaches to balance load bearing capacity and SEA.