Loading rate effect on yield surface of aluminum alloy foams

This paper presents a combined compression-shear test for closed-cell aluminum alloy foams with three different relative densities in order to determine their initial yield surfaces and investigate the influence of the loading rate on the initial yield surface under multiaxial loading conditions. Uniaxial compression and tensile tests have also been performed to determine yield stress in simple load condition. The experimentally measured yield surfaces are compared with three phenomenological yield criteria for metallic foams. The comparison result indicates that three phenomenological yield criteria give a good description of the multiaxial yield of closed-cell aluminum alloy foams when proper plastic Poissonʹs ratio is employed. The experimentally measured yield surface of the tested foams in principal stress plane is independent of relative density in the range investigated. The experimental yield surfaces of three types of aluminum alloy foams all exhibited a slight expansion over the range of loading rates studied.