New constitutive relations in the nonlinear theory of viscoelasticity

In this paper a generalization of Pobedria's viscoelasticity theory is considered for an isotropic solid with non-relaxing volume. Two types of special loads are considered for samples of Pobedria's material — isotropic compression and monoaxial tension. The obtained formulas are used to deduce necessary conditions of non-relaxing behavior of volume. It is shown that the conditions obtained in such a way are not only necessary, but also sufficient for the non-relaxing behavior of volume, even in the case of an arbitrary load.