Sample size effect on the mechanical behavior of aluminum foam

Abstract

The aim of this work is to explore the effect of sample size in three different directions (length, height, and thickness of a sample block), with respect to its cell size, on the mechanical properties of closed-cell aluminum foams. 3D Voronoi models were used to represent a real foam block, and finite element (FE) analysis was performed to simulate the mechanical properties of samples under three different loading conditions (uniaxial compression, shear, and bending). The numerical results match the experimental results. The stiffness and strength of samples with different sizes were normalized by those properties of samples with the maximum size. The normalized stiffness and strength were expressed as functions of thickness of weak cell layers (less constraint cells) and that of the strong boundary layers (strong constraint cells). Furthermore, a parametric study was performed to investigate the effects of the thicknesses of weak cell layers and strong boundary layers on the mechanical properties of aluminum foam. It is concluded that both the stiffness and strength increase with sample size under compression and bending, while they decrease with the increase of sample height under shear. The minimum size of samples characterizing bulk materials under different loading conditions was determined.