Mechanical Characteristics and Quasi-Static Compression Deformation Mechanism of Open-Cell Aluminum Foam with Spherical Cells

In this work we investigated the quasi-static and dynamic compression of spherical cell aluminum foam with homogeneous pore morphology and size. We identified the deformation mechanisms of the aluminum foam in the quasi-static compression at both macroscopic and mesoscopic levels using digital image correlation. The results showed that the compressive strength, plateau stress and energy absorption were significantly improved by increasing the loading strain rate, that is, the spherical cell aluminum foam exhibited obvious strain rate sensitivity. Because of the inhomogeneous cell wall thickness and the random distribution of cell wall defects, the deformation bands dominated the compressive behavior during the compression process, and the strain concentration zones were observed on the single cell hole where the cell wall defects were identified. Meanwhile we examined the implications of compressive behaviors operating on the mesoscopic cell walls and the formation of macroscopic deformation bands. The deformation modes of cells mainly fell into 3 types, i.e. axial compression, shear, torsion and shear combined deformation. The failure mode of the cell walls throughout the deformation zone was mostly determined by shear deformation, which was obviously related with the cell wall thickness and the loading direction.