Recent results from numerical analysis of the microstructure and constitutive properties of foams are presented and relations between these properties and various topological differences in the cellular architecture are illustrated and discussed. The focus is on closed cell foams but parts of the work concern effects of distribution of solid between the cell walls and edges, which then also include open cell foams.

The study is based on a modelling scheme where Voronoi partitioning is conducted, based on seed point distributions coming from random packings of hard spheres. The models are then brought to surface energy equilibrium through use of the Surface Evolver software. Sphere packing, partitioning of space and relaxation of the cellular models are conducted on periodic representative volume elements (RVE), typically containing in the order of 100 cells. Finite element models of the foam architecture is then performed with various sets of periodic boundary conditions in order to study the model topology, convergence rates and extract representative constitutive properties for the studied cases.

The results are compared with other simulation results from the literature, experimental data and measurements made from SEM and CT micrographs. Some differences between evaluations of 2D and 3D representations of the foam materials are also illustrated and discussed.

Aspects of the generation of the models are illustrated, indicating that some model results are virtually unaffected by most of the model details while other results depend strongly on the input parameters and differences between modelling techniques.

Some references are also made to classical foam property estimates coming from dimension analysis of idealised foam structures where the relatively simplistic models in many cases provide surprisingly good estimates of the mechanical properties of the foam materials. There are however also some significant differences that are highlighted and explained in the presentation.