Coupled theory of heat, moisture and deformation

Abstract

Empirical studies [1] in recent time have shown that mechanically applied stress can significantly alter the moisture and temperature distribution in solid media. Such findings are not unexpected and suggest the need to analyze the coupling between mechanical deformation and diffusion due to moisture and temperature. Because of the complexities of the theoretical treatment and procedures involved in determining the physical constants, only a few cases have been treated up to this date. In order to obtain an in-depth insight into the physical phenomenon, it is necessary to rely on the disciplines of mechanics and thermodynamics for analyzing the combined interaction of heat, moisture and mechanical deformation. Based on suitable postulates, a coupled system of governing equations is derived that contain both space coordinates and time as independent variables. Simplification prevails when diffusion and deformation take place quasi-statically. The results also reduced to those obtained earlier when deformation is uncoupled while the classical coupled equations of thermoelasticity are recovered if moisture effects are further neglected. A method of solution is presented that makes use of a hygrothermoelastic potential.