Multiscale stress analysis of porosity clusters as mechanical models of degenerated graphite defects in cast iron

We extend previous results for the stress analysis of a cluster of degenerated graphite in spheroidal cast iron, modelled as a multiscale three-dimensional composite. At the microscale, precipitates of degenerated graphite are modelled as spheroidal voids in a linear elastic matrix. At the mesoscale, clusters of degenerated graphite are aggregates of spheroidal voids. These aggregates are studied by means of a numerical analysis based on finite element simulations. As a second approach, the clusters are seen as homogeneous inclusions made of an equivalent porous elastic material. The average elastic properties of the porous material are calculated using an approach proposed by Tandon and Weng and based on Eshelby's equivalent principle and Mori-Tanaka's estimate. Comparison of the two approaches gives encouraging results in terms of average properties.