Dynamic performances of thin-walled tubes with star-shaped cross section under axial impact

• For the first time, a mode classification of Aluminum thin-wall tubes with star-shape cross section (S-tube) was proposed, the collapse mode was related to the slenderness of thin-walled tube.
• The deformation mode of S-tube with longer fold length significantly influences the energy absorption ability of multi-corner tube.
• A new design of thin-walled tube is proposed. It was proved that the energy absorbing capability of the new design is 40% higher than that of a common polygon tube.

Under axial loading, the thin-walled structures will experience severe plastic collapse at the corners. The presented paper focuses on the axial dynamic performances of the thin wall tubes with star-shaped cross sections (S-tube). Firstly, the impact tests of the Aluminum S-tube samples are performed to confirm the accuracy of numerical simulation. Then, a mode classification chart is given based on simulations with tubes of various dimensions. It is found that the slenderness of tube plays an important role in the deformation mode. Besides, the relationship between the deformation mode and energy absorbing performance are discussed through FE method. The specific energy absorption (SEA) of S-tube is slightly better than the polygon tube (P-tube) due to the fact that the deformation mode of S-tube with longer fold length hinders the potential capability of multi-corner tube. Finally, a new design combining the characteristics of S-tube and traditional polygon tube (P-tube) is proposed. The numerical result shows that SEA of the new design is 40% higher than that of P-tube.