Axial buckling modes and crashworthiness of circular tube with external linear gradient grooves

Abstract

Metallic circular tube with external uniform grooves has excellent behaviors on axial crashworthiness during axial compression because it can generate stable responses. In the present research, three novel energy absorbers are proposed based on uniform grooved tube (UGT), namely, depth gradient grooved tube (D-GGT), thickness gradient grooved tube (T-GGT) and coupling gradient grooved tube (C-GGT). A theoretical model considering both the depth and thickness gradients and an efficient numerical model based on axisymmetric assumption are put forward. Meanwhile, some quasi-static compression experiments are performed to validate the theoretical and numerical models. The results conclude that the deformation of gradient grooved tubes (GGTs) under axial buckling can be classified into two modes, namely, random asymptotic buckling (RAB) and sequential asymptotic buckling (SAB). Compared with UGT, the D-GGT has a slight improvement on the axial energy performance even though the sum of depth of thin-walled sections is constant; for T-GGT, a force-displacement curve with upward trend and an obvious improvement of energy absorption are observed; specially, the energy absorption characteristics of D-GGT and T-GGT will occur simultaneously when C-GGT is subjected to axial loading.