Thermodynamical Considerations

Abstract

Suppose that the thermodynamical state of each material element is uniquely defined by the values of a finite set of state variables even in an irreversible process. Such a phenomenological theory is, of course, restricted to a limited class of materials on the one hand and to processes running not too far from thermodynamical equilibrium on the other hand. A thermomechanical process starts in the initial state B _to of the body which is characterized by the initial configuration and by the initial thermodynamical state of each material element. The initial state is described by the prescribed thermomechanical boundary conditions, the prescribed body forces and energy sources acting inside and on the surface of the body. The process is governed by the field equations (balance equations) and by the constitutive law of the material. We focus our attention on the constitutive law which governs the local thermomechnical process within the thermodynamical state space.