Different models for the fracture toughness, KIC, of porous materials have been proposed to describe KIC as a function of the porosity P. They have in common that beside P at least one additional parameter exists that has to be adjusted to the measured data. Based on the cubic structure, we present a geometrical 3D model without any arbitrary parameter, which predicts the KIC the toughness, GC, and the Young's modulus, E, of a porous material. The model comprises three variants, depending on the material properties like open or closed porosity. It is in good agreement with a large amount of experimental data from different research groups.
