Plastic deformation and compressive mechanical properties of hollow sphere aluminum foams produced by space holder technique

• Pore distribution was controlled in regular architecture for hollow sphere aluminum foams.
• Hollow sphere aluminum samples with regular pore distribution were compared with irregular ones.
• Effect of loading direction on the foams with regular architecture was examined.
• Deformation mechanism of hollow sphere aluminum foams was controlled by configuration of pores.
• A good agreement was found between the plastic properties of samples and finite element results.

In this study, experimental procedure and numerical methods were utilized to evaluate the effect of regular and irregular pore distribution as well as loading direction on compressive properties and deformation mechanism of hollow sphere aluminum foams. In order to study scaling laws, different volume fractions of the regular samples were produced and loaded in horizontal and vertical directions to address the loading conditions effects. For this purpose, expanded polystyrene (EPS) grains were expanded to a designed diameter size and positioned in different configurations. Compression test results showed higher elastic properties for irregular sample due to the thicker cell walls while energy absorption capability at high strains was found to be reduced due to the non-uniform deformation in comparison with regular foams. In regular samples, a nonlinear behavior in the elastic regime was observed since the imperfections during casting procedure. Furthermore, similar deformation mechanisms were found for the set of samples with similar pore configurations indicating the feasibility of controlling deformation mechanism by manipulating morphological characteristics. Finite element results well predicted deformation mechanism of structures and plastic properties of regular hollow sphere samples especially for plateau stress with less than 12% relative error.

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