Many results on micromorphic media can be found in the literature, where
the equations of motion and the energetic foundations of the Eringen
micromorphic continuum have been well established. The present paper has
been devoted to the continuum modeling of a finite number of interacting,
separated continua (microdomains) at the microscale, in which the strain
energy has been formulated through a generalization of the Cauchy–Green
deformation tensor, resulting in a degenerate metric at the considered scale, and a
Green–Lagrange strain tensor. The equilibrium equations have been obtained by
systematically applying the method of virtual power. For one of the first time,
boundary layer conditions appear in micromorphic mechanics. The paper concludes
with a discussion on the number of constitutive parameters, shown to coincide, in
number, with those of classical (Cauchy) elasticity, together with the recovery of
micropolar continua as a special case and wide spectrum of applications of the
proposed framework. Further details concerning the algebraic expressions of the
tensors involved are provided in the Appendices.