Deformation and energy absorption of a cubic box under body-diagonal compression

This paper investigates the crashworthiness of thin-walled cubic boxes subjected to body-diagonal compression. Compared with conventional axial loading, the proposed strategy achieves more uniform collapse, reduces the initial peak crushing force, and enhances the plateau force. Experiments and numerical simulations were conducted to compare compressive responses under both loading conditions. Results show that, with the same wall thickness and mass, body-diagonal compression triggers more complex plastic deformation. In addition to fixed plastic hinges, traveling plastic hinges are generated, which dissipate significantly more energy and engage more material in plastic flow. Owing to the point contact with the loading plate, the initial peak force is markedly reduced, producing a force–displacement curve closer to the ideal rectangular profile. Under quasi-static compression, the cubic box compressed along the body-diagonal exhibits a 49% increase in specific energy absorption (SEA), a 157% improvement in crushing force efficiency (CFE), and a reduction of the undulation of load-carrying capacity (ULC) from 0.50 to 0.21, relative to axial loading. Dynamic impact tests further confirm its superior performance, with a lower initial peak force and greater energy absorption capacity. Based on the observed deformation mechanisms and energy dissipation of traveling hinges, a simplified theoretical model is proposed to predict the mean crushing force. The findings demonstrate the advantages of body-diagonal compression and provide a promising design strategy for high-performance energy-absorbing structures.