Interpretation of micromorphic constitutive relations for porous materials at the microscale via harmonic decomposition

Micromorphic theories became an established tool to model size effects in materials like dispersion, localization phenomena or (apparently) dependent properties. However, the formulation of adequate constitutive relations with its large number and respective parameters hinders usage full micromorphic theory, which has 18 already isotropic linear elastic case. Although it is clear that these are related predicted effects, individual meaning single been rather unclear. The present work tries elucidate interpretation their parameters. For this purpose, a harmonic decomposition applied governing equations theory. modes interpreted at microscale using homogenization method for simple volume element spherical pore. resulting boundary-value problem solved analytically linear-elastic case harmonics closed-form expressions all These values used predict effect torsion slender foam specimens. predictions compared experimental results from literature.