Effect of sample shape on compression behavior of aluminum foams

Abstract

The paper deals with the effect of the sample shape on the uniaxial compression behavior of powder metallurgically prepared closed cell aluminum foams with surface skin. The combination of various geometry shapes of aluminum foams is important in the case of design and development of optimal seismic and impact energy absorbers. Aluminum foam samples of the same density were prepared by a powder-metallurgical process from two different aluminum foam alloys: ductile AlMg1Si0.6 + 1 % wt. TiH2 and brittle AlSi10 + 1 % wt. TiH2. The samples were foamed in three different geometric shapes (cylinder, triangular prism and square prism) with the same cross-sectional area of 490 mm2. The samples contain surface skin. Quasi static uniaxial compression tests were performed parallel to the remaining outer surface skin on the foams with the constant density. From the obtained stress–strain curves compression strength, plateau strength, energy absorption at 50 % strain and densification strain were determined. The results indicate that there is an effect of sample shape on the aluminum foam mechanical properties: triangular prism mechanical properties are the worst with respect to cylinders and square prisms. The results indicate that the square prism compression properties could outperform compression properties values of cylinders for both ductile and brittle aluminum matrix alloy. Densification strain is shape independent. The observed results were explained by foam inhomogeneity, size of pores, thickness of surface skin region and stiff edges of used shapes.