Cutting-induced end surface effect on compressive behaviour of aluminium foams

Abstract

Three cutting methods, i.e. electrical discharge machining (EDM), band saw (BS) and water jet (WJ), were used to prepare cuboid samples of closed-cell aluminium Alporas foam. On the end surfaces of the prepared samples, local roughness of mesoscopic structural components (i.e. cell wall, node and facet) and global roughness for the entire cut surface were measured using confocal microscopy. Furthermore, quasi-static uniaxial compression tests were performed with intermittent unloading-reloading. In the initial stage of compression, the measured loading stiffness and unloading elastic modulus are highest, intermediate and lowest for the EDM-cut, BS-cut and WJ-cut samples, respectively. This difference in measured compressive properties has been correlated with the difference in end-surface roughness associated with different cutting methods. However, the peak and plateau of compressive stress and the unloading elastic modulus in the plateau stage are insensitive to cutting method. An analytical model has been developed to elucidate the observed compressive behaviour and shed light on the responsible mechanisms.