Open-cell ceramic foam filters are used for the casting process of molten steel to reduce the amount of non-metallic inclusions. Within the collaborative research centre CRC 920 multifunctional filters, made of carbon-bonded alumina, are investigated. Previous investigations showed a creep deformation behaviour of the bulk material and filters at temperatures in the range of the molten metal.
During the casting process no sufficient experimental observations can be performed on the foam due to the high speeds and temperatures, which is why numerical investigations are needed. Detailed finite element simulations of geometrically very complex foams and filtering process would require very large meshes and computational power. Thus, a numerical material description is needed, which can be used to improve the properties of the foam filters based on numerical parameter studies.
For determination of the numerical foam creep deformation behaviour the knowledge of bulk material properties and the foam geometry are needed to perform numerical simulations. The bulk material behaviour is described based on creep tests using compact specimens. Different real foam structures are obtained using computed tomography (CT) scans. Afterwards, the creep deformation of these real foam structures is compared with the creep deformation of the experimental-numerical approach for validation issues. Moreover, the influence of different foam topology parameters (strut shape factor, polydispersity and anisotropy) are discussed for an improvement of the elastic stiffness and creep resistance of real foams.