Mechanical behavior of nested multi-tubular structures under quasi-static axial load

• Energy absorption of not-annealed cylindrical tubes is more than that of annealed tubes.
• With the same mass, increasing the tubes of a structure leads to more SEA.
• Overlap among the tubes of a multi-tabular structure reduces the length of collapse.
• In multi-tabular structures overlap leads to little increase in absorbed energy.
• By increasing thickness, the maximum and mean forces of the collapse become more.

In this paper, parameters affecting the collapse of nested multi-tubular thin-walled aluminum structures as one of the energy absorbers have been studied experimentally and using simulation techniques. In empirical studies, after annealing and determining the mechanical properties of 6101 aluminum, the properties of four different combinations of nested four-tabular structures located as equi-axed within each other were examined under quasi-static compression. Simulations and parametric investigations were done using finite element LS-Dyna software which had a good consistency with the experimental results. Simulations showed that multi-tabular structures have better performance for absorbing impact energy compared to single-tube structures with the same thickness, height and mass. It was also observed that the increase in the number of tubes from 1 to 2, 3, 4 and 5 leads to an increase in specific energy as 37%, 66%, 105%, and 88%, respectively as well as the increase in the crash force efficiency as 62%, 96%, 154% and 185%, respectively. In this study, the effects of thickness and the mean diameter of tubes on the characteristics of the collapse of structures were also investigated.