Energy-absorbing properties of thin-walled square tubes filled with hollow spheres

The smooth thin shell structure has exhibited significant advantages in light weight and high energy absorption and been widely applied in transportation, aerospace fields. This study proposed the thin-walled square tube filled with hollow aluminum metal spheres (TST-HS) to improve the crashworthiness. In this structure, hollow aluminum spheres were filled into thin-walled square tubes in different stacking modes, such as simple cubic (SC), body-centered cubic(BCC), and face-centered cubic (FCC). A series of quasi-static compression experiments and numerical simulations were conducted to investigate the deformation mechanism and crashworthiness of TST-HS. The results indicated that filled hollow spheres lead to the change in the deformation mode and an increase in the number of plastic hinges of TST-HS. The mean load of TST-HS was increased by 68.98% and 15.6%, respectively, compared to the square tubes and the foam-filled tube of same mass. Parametric studies show that the wall thickness, size and stacking modes of the hollow spheres have major impacts on the crashworthiness of the TST-HS. Energy analysis reveals the contribution of the interaction between hollow sphere and square tube to the total energy absorption of TST-HS.