Thermomechanical response of nonlinear viscoelastic materials

• Published in: Journal of thermal stresses 2023-07, Vol.46 (7), p.588-605
• Main Authors: Khoeini, A., Imam, A., Najafi, M.
• Format: Article
• Language: English
• Subjects: Balance of entropy; Differential equations; Energy conservation law; Entropy; Free energy; internal rate of production of entropy; Nonlinear response; second law of thermodynamics; thermo-viscoelastic materials; Thermodynamics; Thermomechanical properties; Viscoelastic materials; Wave propagation
• ISSN: 0149-5739; 1521-074X
• DOI: 10.1080/01495739.2023.2189924

In this article, the thermomechanical properties of the classical and nonclassical viscoelastic materials with particular emphasis on the entropy are studied in the framework of continuum thermodynamics. Specifically, considering the Clausius integral as "Part I" of the second law of thermodynamics in the classical formulation of continuum thermodynamics, the entropy function for various classes of nonclassical thermo-viscoelastic materials is shown to exist. This is achieved by employing the first law of thermodynamics and a scalar potential known as the Helmholtz free energy function. In addition, another function known as the internal rate of production of entropy defined for the classical and nonclassical thermo-viscoelastic materials is adopted to obtain a balance law for the entropy. Finally, upon linearizing the theory, a coupled system of differential equations is obtained for the nonclassical thermo-viscoelastic materials, which under some special circumstances, permits propagation of damped harmonic waves in the viscoelastic medium.