Determination of an RVE and identifying a representative idealised model for specific surface and volume of metal foams

Open porous metal foams are extremely inhomogeneous and very complex structures. In order to simplify this complex composition consisting of nodes and struts, different periodic structures have to be defined. These periodic structures represent the inhomogeneous microstructure and have the same geometrical properties in a macroscopic view. Thus, the macroscopic properties of the material can be determined without knowing the exact microstructure. The representative volume element is the smallest part of a sample and has the same properties as the whole structure. This representative volume element is determined for the macrostructure, with the help of computed tomography data in terms of specific surface area and bulk volume in a first step. In a second step, an evaluation of different models for periodic porous structures used in the literature is done. The idealised models are compared with the properties of the computed tomography data set of real aluminum metal foams with different node sizes and different strut cross-sections. With regard to a later use of the models in the implementation of the coating process of metal foams by means of electrodeposition, all geometrical properties are determined depending on a coating thickness between 0μm and 263,71μm. The knowledge gained here is not only helpful in the optimisation of the simulation of the electrodeposition process for coating the foams, it also brings benefits in the simulation of filters, catalysts or heat exchangers, consequently in all areas of application of open porous foams where the specific surface and bulk volume of the foams are of interest. This includes all open-porous foams made of polymers, metals or ceramics. In conclusion, by applying a small offset, different unit cells are particularly suitable for describing the specific surface and bulk volume of aluminum foams.