Abstract
The four-point bending test was used to determine the deformation behaviour of foamed panels and sandwiches prepared by powder metallurgical route from casting as well as wrought aluminium alloys. Bending properties were examined with respect to the thickness of the sample, cell-wall material, and apparent density of the foam. Experiments have shown that the deformation mechanism significantly depends on the choice of cell-wall material; cast-alloy-based foams are brittle and tend to fracture, while wrought-alloy-based foams are able to withstand a higher level of plastic deformation without cracking. It has been found that the Young's modulus of the foam, which is usually related to its apparent density, cannot be satisfactorily used for the calculation of bending stiffness of foamed panels. This is because of the surface skin on the foam, which causes inhomogeneous distribution of cell-wall material along the thickness of the sample and distorts its apparent density. Therefore, the real moment of inertia of the foam cross-section should be applied. This moment can be approximately determined from the square weight of the foamed sample.

Key words
Al foams, cast-alloy-based foams, four-point bending test, deformation behaviour

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