Effect of cell size on the energy absorption of closed-cell aluminum foam

Abstract

Abstract Aluminum foam could be used as a defense against explosion and shock wave. Its energy absorption capability is an important indicator to evaluate its blast resisting ability. But since the impedance of aluminum foam is much lower than that of metal, it is hard to measure its exact stress-strain relation by means of the traditional Split Hopkinson pressure bar (SHPB) method. To evaluate the energy absorption characteristic of aluminum foams of varied cell sizes, an improved SHPB method is proposed. This improved method can enhance the accuracy of the stress-strain curve of aluminum foam and by using a longer striker, might increase the strain on the samples. Two aluminum foams of different cell sizes were selected. The experimental results show that the cell size of the aluminum foam and the strain rate have a significant effect on the compressive characteristics and energy absorption. Smaller cell aluminum foam is stronger than that with larger cells due to fewer flaws in the microstructure. Aluminum foam of a smaller cell size can absorb more energy than larger cell aluminum foam due to higher plateau stress. The energy absorption of smaller cell aluminum foam increases by 42 % at strain rate 3579 s−1 compared with quasi-static compression while larger cell foam increases 55 % at a strain rate of 1586 s−1.