Chemical affinity tensor and chemical reaction front propagation: theory and FE-simulations

We develop an approach to studying the influence of stresses and strains on the kinetics of chemical reaction fronts based on the expression of the chemical affinity tensor that determines the configurational force acting at the transformation front. For a chemical reaction between diffusive gaseous and deformable solid constituents we formulate a kinetic equation in a form of the dependence of the reaction front velocity on the normal component of the chemical affinity tensor that in turn depends on stresses. We describe a locking effect-blocking the reaction by stresses at the reaction front and define the forbidden stresses or strains at which the chemical reaction cannot go. We develop a finite-element model to describe how stresses affect a chemical reaction front propagation. To demonstrate how the model works we consider a chemical front propagation in a plate with a groove assuming that the solid constituents are linear elastic. Comparing the front propagation in the vicinity of the groove top and at the bottom of the plate far from the groove we study how the stress concentrations, internal stresses and external loading, material and reaction parameters affect the reaction.