Experimental and numerical study on the crashworthiness performance of a hybrid energy absorber with expanding-splitting-bending process

The single deformation mode of splitting tube significantly restricts its energy absorption capability. To address this limitation, in this paper we propose a new hybrid absorber with an external die added to the outside of the expanding-splitting tube, thus the circular tube undergoes sequential expanding, splitting, and bending deformations. We fabricate samples and perform quasi-static compressive experiments on the splitting tube, expanding-splitting tube, and proposed hybrid splitting tube. Experimental results show that the hybrid tube deforms in a controlled and ordered way as designed. Remarkably, the steady crushing force of the hybrid tube is 52.1% and 221.6% higher in comparison to that of the same tube with splitting mode, and expanding- splitting mode, respectively. The crushing force responses and deformation processes are well captured by finite element simulations. The relative errors of the steady crushing forces and energy absorption are within 5.0%. A parametric analysis is performed. We show that the structure parameters play an important role in the crashworthiness performance. In particular, the tube with thicker walls has a larger crushing force and a higher specific energy absorption. The small cracking number and spacing between the inner and outer die can trigger unstable deformation. Our results can advance the engineering application of splitting tubes and the lightweight design of energy absorbers.