Crashworthiness of Circular Tubes with Rhombus Star Grooving Pattern

Abstract

Thin-walled structures are widely used as energy absorbers in aircraft and automobiles. They have a high load-bearing capacity despite their small thickness. Due to their lightweight and high energy absorbing capacity, their application is becoming increasingly diverse. In this study, the structural response and crashworthiness performance of circular thin-walled grooved tubes were investigated under axial loading. Rhombus star grooving patterns were introduced to relatively short and thin tubes to enhance crashworthiness performance. The optimum crashworthy performance should provide a proper initial stiffness and a stable crushing force after the initial collapse. Experimental and numerical analyses have been conducted to investigate the influence of various geometrical patterns on crushing behavior and crashworthiness parameters. It was found that several multi-lobe diamond deformation modes can be triggered for a tube with a constant diameter to thickness ratio (D/t = 59.25). An increased number of lobes and folds led to higher specific energy absorption (SEA) and crushing load efficiency (CLE), up to 31% and 34.5% respectively. Parametric studies showed that groove depth can be used to achieve a desirable deformation mode that increases both SEA and CLE simultaneously. The proposed tubes would apply to the crashworthiness design of helicopter subfloor structures and vehicle bodies.