Numerical analysis of the impact resistance in aluminium alloy bi-tubular thin-walled structures designs inspired by beetle elytra

Thin-walled tubular structures are commonly used in automotive and aerospace applications because of their high strength and lightweight characteristics. In this paper we propose a new bionic bi-tubular thin-walled structure (BBTS) inspired from the internal structure of the lady beetle elytron. Six types of BBTSs with different geometric parameters and same type of material were simulated under axial dynamic impact loading with a weight of 500 kg and a velocity of 10 m/s using nonlinear finite elements. The comparison between BBTSs with equal mass shows that the thickness of the inner wall and the cross-sectional configurations influence significantly the energy absorption of the structure. BBTSs show an optimized crashworthiness behavior when the inner wall thickness is between 1.6 mm and 2.0 mm. Circular and octagonal BBTSs also show improved absorption characteristics when the inner wall thickness is 2.0 mm. We also evaluate the energy absorption of periodically distributed BBTS against cellular configurations with irregular topology. The energy absorption characteristic of the BBTS with regular distribution is higher than the one of BBTS with irregular distribution, which indicates that the optimized regular structure has a general improved mechanical performance compared to the original bionic topology.