EXTRASTRAINS OF THE MICROSTRUCTURAL CONTINUUM WITH FREE DIRECTOR
A non-linear mathematical model of thermoelastic continuum with microstructure is developed. The model is described in terms of 4-covariant field theoretical formalism. A Lagrangian density for thermoelastic continuum with one free microstructure director is given and the least action principle is formulated. Corresponding 4-covariant field equations of micropolar thermoelasticity are derived. Constitutive equations of thermoelasticity with one free microstructural director are discussed. Variational symmetries of the thermoelastic action are used to formulate covariant conservation laws in a plane spacetime. Following the usual procedure for micropolar thermoelastic Lagrangians functionally independent rotationally invariant arguments are obtained.