Failure of aluminum foams under multiaxial loads

Aluminum foams are currently being considered for use in lightweight structural sandwich panels and in energy absorption devices. In both applications, they may be subject to multiaxial loads. The designer requires a criterion to evaluate the combination of multiaxial loads which cause failure. Here we measure the failure of one open- and one closed-cell aluminum foam under biaxial and axisymmetric triaxial loading. The data are compared with three yield criteria for metallic foams. The first criterion is based on analysis of the failure mechanisms of an ideal foam. It overestimates the measured foam yield surface: the discrepancy can be related to imperfections in the foam structure. The other two criteria are phenomenological: one is based on the well-known Drucker–Prager criterion while the other is based on a recently developed yield surface for compaction of powders. Both phenomenological yield surfaces give a good description of the multiaxial failure of the aluminum foams tested in this study.