Multiaxial Yield Behaviour of Al Replicated Foam

Two major classes of models for the multiaxial yield behaviour of aluminium foams are found in the literature. One is based on the foam properties and uses empirical constants determined by fitting of experimental data. The other is based on a mean-field approach where the foam is considered as a two-phase composite of Al matrix containing void inclusions. The present investigation is a confrontation of these models with the measured behaviour of replicated microcellular aluminium using multi-axial testing. Two tests are used. The first consists of compression of a thin-walled foam pipe with an internal pressure applied by inflating a bladder. This gives plane stress data under axial compression (σ1 < 0) and radial tension (σ2 > 0 with σ3 ≈ 0). A special rig is also constructed to conduct triaxial tests on cubic foam specimens, under different stress states in tension or compression independently controlled on each of the principal directions (σ1, σ2, σ3). The results of these multiaxial (biaxial and triaxial) tests on replicated aluminium foam will be presented, along with a comparison of the predictive capabilities of the different models.