New effective moduli of isotropic viscoelastic composites. Part I. Theoretical justification

According to the approach based on the commonality of problems of determining effective moduli of composites and viscoelastic solids, which properties are time-inhomogeneous, it is assumed that a viscoelastic solid is a two-component composite. One component displays temporal properties defined by a pair of Castiglianian-type effective moduli, and the other is defined by a pair of Lagrangian-type effective moduli. The Voigt and Reuss averaging is performed for the obtained two-composite solid with the introduction of a time function of volume fraction. In order to determine closer estimates, a method of iterative transformation of time effective moduli is applied to the viscoelastic Voigt-Reuss model. The physical justification of the method is provided. As a result, new time effective moduli of the viscoelastic solid are obtained which give a closer estimate of temporal properties as compared to the known models.