Micromorphic continuum model for electromagnetoelastic solids

The microcontinuum theory of electroelasticity is considered for polarizable dielectrics on the basis of dipole and quadrupole densities as microfields. Electromagnetic contributions to force, couple, and power are derived, and their correspondence with quantities evaluated in terms of macroscopic polarization and magnetization is examined. A constitutive model that accounts for dissipation is proposed via internal variables satisfying suitable evolution equations. This approach reveals different roles of polarization and strain measures in dissipative processes. The link between the spin inertia tensor and the pair of dipole and quadrupole per unit mass is exploited to derive a nonlinear system of governing equations for a reduced set of variables. The special cases of microstretch and micropolar continua are discussed.