An experimental study of the deformation rate sensitivity of PM aluminium foams

This paper presents an experimental study using a new testing device based on a nylon Hopkinson bar system with 60 mm diameter, which provides a solution for both the impedance match and the problem of reasonable specimen size when testing metal foams. PM aluminium foams cylinders with closed outer skins 45 mm diameter and 60 mm length were tested in both the standard SHPB configuration specimen between two nylon bars , and the block bar configuration specimen in front of input bar to obtain a higher loading rate. Despite unavoidable scatter for this kind of materials, the slight rate sensitivity could be observed. In addition, tests with strain rate jumps on the same specimen were carried out static loading after a dynamic loading or dynamic loading after static one . A discontinuity of stress strain curve is found for the two cases. This gives another proof that this foam is rate sensitive in this range of loading rat