A Numerical Study on the Axial Loading and Energy Absorption of Foam-filled Conical Tubes

Foam-filled thin-walled tubes have been considered to be desirable energy absorbers under axial loading due to their relatively high energy absorption and crush force efficiency compared with an empty tube. The combination of a conical tube and foam filler in particular is preferable to an empty conical tube for energy absorption purposes as such tube can withstand axial loading in a stable manner. Despite this, relatively a very few studies have been reported on the energy absorption performance of foam-filled conical tubes. This paper compares the energy absorption response of empty and foam-filled conical tubes under quasi static axial loading, in terms of variation in their wall thickness, semi-apical angle and density of foam filler. A parametric study has been performed using a finite element (FE) model validated using existing theoretical and numerical results. The FE model was developed using explicit finite element code LS-DYNA. From the parametric studies, a factorial study has been carried out to evaluate the relative effect of each appropriate parameter on the crush and energy absorption responses of foam-filled conical tubes. Overall, the results show that energy absorption capacity is significantly enhanced and a more stable crush response can be obtained by filling the conical tube with metallic foam filler. Moreover, the advantages of using a foam-filled conical tube as an energy absorber are highlighted. As a practical outcome of this study, an empirical formula and design information will be developed for the use of foam-filled conical tubes as energy absorbers