Mechanics of hollow sphere foams

Models for the mechanical properties of foams suggest that closed-cell foams should have significantly higher modulus and strength than open-cell foams, especially at low relative densities. In practice, as a result of defects in their microstructure, the measured properties of closed-cell metallic foams are similar to those of open-cell foams of the same relative density. Hollow sphere foams provide an alternative microstructure with the potential for improved properties for low-density metal structures. Here, we analyze the elastic moduli and initial yield strength of hollow sphere foams. The results indicate that their theoretical values of moduli and strength are intermediate to those for open- and closed-cell foams. With suitable manufacturing techniques, hollow sphere foams have the potential for improved mechanical properties compared with existing metallic foams.