magnetic coupling

Equilibrium theories for a continuum body may be formulated by either of the
following the classic paradigms: (1) We begin with the stress postulation (Cauchy’s formulation) and write down the kinematics, conservation laws, and
constitutive relations. In this way, one can obtain a system of field equations
which, presumably, can be solved upon specifying boundary conditions and
determine the equilibrium state of the body. (2) A second way is to start from
the energy postulation (Green’s