Non-equilibrium thermodynamics and variational principles for fully coupled thermal-mechanical-chemical processes

In this paper, the chemical Gibbs function variational principle, the Helmholtz function variational principle and the internal energy variational principle based on irreversible thermodynamics are proposed for the thermal-chemical-mechanical fully coupling problems. The complete fully coupling governing equations, including the heat conduction, mass diffusion and chemical reactions, are derived from the variational principles. The convective effect can also be derived in the diffusion and energy equations from the variational principles naturally. Moreover, the concentrations and entropy jump conditions on the moving interface between the products due to chemical reactions and the matrix can be derived from the variational principles naturally. This work provides the basis for the analyses and computations of thermochemomechanical coupling problems.