Effects of the strain rate and alloying on the compression characteristics of closed cell aluminum foams

Abstract

Though closed cell Al foams have extremely low density and high energy absorption performance, they are expected to improve the compressive strength and to clear the dynamic compression characteristics for much more practical application. In this research, the effects of density, test piece size and alloying (Al-10.0 mass%Zn-0.3 mass%Mg) on the uniaxial static and dynamic compressive strength was examined. Dynamic compressive strength were examined by the Split Hopkinson Pressure Bar (SHPB) method and the drop weight impact test device. As a result, the dynamic plateau stress of pure Al foams was about 1.3 times larger than the static one, and there was a scale effect of test pieces. The dynamic plateau stress of Al alloy foams was about 1.1 times larger than the static one, and there was less scale effect of test pieces for plateau stress because the cell walls of Al alloy foams tend to collapse owing to brittleness by alloying. The effect of the inner gas enclosed in cells on the dynamic response of pure Al foams by SHPB is also discussed. When providing inner gas vent holes, dynamic plateau stress decreased close to the static one. With Al foams, the increasing in dynamic plateau stress may be caused by the inner gas pressure rising under dynamic compressive conditions as well as influence of the strength and ductility of the cell wall. © 2009 The Japan Institute of Metals.