Study on the energy absorption of the expanding–splitting circular tube by experimental investigations and numerical simulations

• A new energy absorber combines expansion and splitting of a circular metal tube.
• The new combined absorber gives higher absorption power with compact dimension.
• Bending of the strips in the second phase gives full utilization of tube material.

This paper presents experimental and numerical investigations of a new type of combined energy absorber which working on the principle of expanding and splitting of the circular steel tube. In the first phase of deformation the tube is expanded by the cylinder part of the die. Second phase of deformation characterizes splitting of the expanded part of the tube into strips along the initial sawcuts by the cone part of the die. The strips bend outwards with certain radius to the end of the second phase. Quasi static compression test shows that this type of energy absorber is completely feasible and the combined absorber has 95.34% higher maximal force in compare with absorber which uses only expansion process of deformation. Using this system of deformation, the total energy absorption is obtained by the three mechanisms: elastic–plastic bending of the tube, splitting of the tube wall and friction between the tube and the die. The effect of friction coefficient is studied by simulation, it is found that the effect on friction energy is significant but negligible on splitting energy and plastic energy.