Effects of cell irregularity on the elastic properties of open-cell foams

Foams are more and more widely used because of their high mechanical properties relative to their low density. Most available mechanical models are based on idealised unit-cell structures. A significant disadvantage of the unit-cell modelling approach is that it does not account for the natural variations in microstructure that are typical for most foam structures. Our objective has been to investigate how the cell irregularity affects the elastic properties of open-cell foams. We generated periodic, three-dimensional (3D), random samples with different degrees of irregularity, and used finite element analysis (FEA) to determine the effective elastic properties. The geometrical properties were investigated for 3D random open-cell foams and related to the elastic properties. The results indicate that the more irregular the foams, the larger will be their effective Young's modulus and shear modulus at constant overall relative density. On the other hand, the bulk modulus reduces with increasing degree of cell irregularity, while the Poisson's ratio is largely independent.