The application of foams is widespread in many industrial scopes, because of the capability of the material as energy absorber or thermal controller and the possibility of realizing them in different materials as polymers, metals and ceramics.In this paper an original FE modelling of open cell aluminium foam by means of solid elements is performed. The equivalent model presents a structure made of Kelvin cells with ligaments characterized by variable circular sections. A detailed shaping of ligaments and nodes of the cell has been tuned starting from literature and original experimental evidences. Consequently, a calibration of the model, based on the experimental foam characterization, permitted to obtain an original solid model of the foam, whose structural behaviour is equivalent to the actual one. The use of sub-structuring techniques permits to perform FE analyses on solid elements models of specimens with actual dimensions and to combine high accuracy in stress field evaluation with compatible computational effort.