Hole and notch sensitivity of aluminium replicated foam

The flow and failure behaviour of replicated pure aluminium foams in the presence of holes and notches is explored, varying the pore size and the notch depth or hole radius. Flat dog-bone tensile specimens containing a cylindrical hole, and cylindrical V-notched samples of 400 mu m and 75 mu m pore size microcellular aluminium were tested. Both pore size foams exhibit a notch strengthening effect, i.e. the peak failure stress increases as the depth of notches in cylindrical samples increases. In dog-bone samples, the presence of a hole ranging from 0 to 4 mm in diameter (in a sample 9 mm wide) does not affect the net section peak failure stress of the 75 mu m foam while the 400 mu m pore size foam exhibits a slight increase in net section failure stress as the hole diameter is increased to 2 mm. Plastic flow curves for notched and hole-containing samples are accurately predicted by a finite-element simulation based on the Deshpande-Fleck [Deshpande VS, Fleck NA. J Mech Phys Solids 2000;48:1253-83] flow law, showing that the observed trends in the data are predominantly mechanical in nature, and strongly linked to the presence of stress triaxiality at the centre of the notched samples. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.