Low-velocity impact of density-graded foam-filled square columns

In this paper, low-velocity impact of square columns filled with density-graded foam (DGF) is investigated experimentally, numerically and analytically. The low-velocity impact experiments are carried out to study the effect of density gradient on the deformation patterns and energy absorption of the DGF-filled columns. Numerical calculations are performed to study the effects of density distribution mode, density difference, average density of DGF and wall thickness of square column on the energy absorption. According to the energy method and basic folding element theory, the instantaneous dynamic crushing force is predicted analytically. The analytical predications are in good agreement with experimental results. It is found that the DGF-filled columns have excellent energy absorption capacity and low initial peak force compared to the uniform-filled columns with the same weight.