Characterization of close-celled cellular aluminum alloys

The deformation behaviour of two different types of aluminium alloy foam ar e studied under tension, compression, shear and hydrostatic pressure. Foams having closed cells are processed via batch casting, whereas foams with se mi-open cells are processed by negative pressure infiltration. The influenc e of relative foam density, cell structure and cell orientation on the stif fness and strength of foams is studied; the deformation mechanisms are anal ysed by using video imaging and SEM (scanning electronic microscope). The m easured dependence of stiffness and strength upon relative foam density are compared with analytical predictions. The measured stress versus strain cu rves along different loading paths are compared with predictions from a phe nomenological constitutive model. It is found that the deformations of both types of foams are dominated by cell wall bending, attributed to various p rocess induced imperfections in the cellualr structure. The closed cell foa m is found to be isotropic, whereas the semi-open cell foam shows strong an isotropy. (C) 2001 Kluwer Academic Publishers.