Strain Gradient Effects in a Thermo-Elastic Continuum with Nano-Pores

The thermo-mechanical balance equations for a porous material with big irregular pores are derived from the general ones for a medium with ellipsoidal microstructure by imposing the kinematical constraint of micro-stretch bounded to the macro-deformation: in this case the microstructure disappears apparently (it becomes latent) and the response of the material involves higher gradients of the displacement without incurring known constitutive inconsistencies.