Energy absorption optimisation of an origami-shaped crash box under axial loading

Abstract

The crease line formed in an origami-shaped crash box (OSCB) acts as a geometric imperfection and mode inducer. Such geometric imperfections make it possible to protect occupants by lowering the peak force in the event of a collision. The OSCB also shows desirable performance as a crashworthy structure by inducing a collapsing mode with excellent energy absorption. There are many studies on crash boxes with origami patterns applied, but few studies on performance optimisation. This article describes the structural optimisation of an OSCB to maximise the specific energy absorption (SEA) by setting the corner length c and module length l as design variables. Numerical and experimental investigations of the crashworthiness performance were conducted by comparing the optimised OSCB to a circular crash box (CCB), which is known to have the best SEA among straight tubes. The numerical and experimental results were in good agreement, with the optimised OSCB collapsing into the diamond mode. The results of the numerical comparison showed that the SEA and the crush force efficiency (CFE) of the optimised OSCB were increased by 5.94% and 115.58%, respectively. However, in a quasi-static axial crushing experiment, the SEA of the optimised OSCB was 10% lower than that of the CCB, and the CFE was increased by 88.5%. The optimised OSCB in this study displayed an improvement in the SEA compared to the reference OSCB, as well as a reduction in the difference from the CCB, indicating high maintenance performance of the CFE.