Enhancing energy absorption of circular tubes under oblique loads through introducing grooves of non-uniform depths

Compared with the excellent energy absorption performance under axial loading, thin-walled tubes are vulnerable to instable global bending under oblique loading condition. In this paper, a novel design was developed to improve the energy absorption performance of the thin-walled circular tubes under oblique loading by introducing multiple circumferential grooves with non-uniform depths. Quasi-static experiments and finite element simulations were carried out for tube specimens with different groove configurations. Theoretical models were developed to explain the different energy absorption performance of different tubes. The effects of the loading angle and the friction condition on the energy absorption were also investigated. The results highlight the advantages of the gradiently grooved tubes with groove depth decreasing from loading end to fixed end over the uniformly grooved tubes and the original tubes under the oblique loading condition. The work in this paper can provide a guide for the design of advanced energy absorbing devices for arbitrary loading condition.