Abstract: The effects of relative density of magnesium alloy foams on their dynamic mechanical properties and energy absorption characteristics are investigated. Split Hopkinson pressure bar (SHPB) is used to evaluate the dynamic compressive behaviors of magnesium alloy foams with different densities. The experimental results show that, with the increase in relative density, the yield stress and platform stress increase significantly while the densification strain decreases. Based on the experimental results, the fitting equations of yield stress and relative density are obtained. The energy absorption properties of metal foams are characterized by energy absorption per unit volume, energy absorption efficiency and ideal energy absorption efficiency. The higher the relative density of magnesium alloy foams is within a certain range, the higher the energy absorption capacity per unit volume is. The energy absorption efficiency decreases slightly, but it is steady at about 0. 3, while the stress corresponding to the highest absorption efficiency increases. Magnesium foam is a kind of material with better protective performance, with the ideal energy absorbing efficiency reaching 0. 9.

Key words: metallic material, magnesium alloy foam, relative density, dynamic mechanical property, energy absorption characteristic