A Framework for Coupled Deformation-Diffusion Analysis with Application to Degradation/Healing

Abstract

This thesis focuses on the formulation and numerical implementation of a fully coupled continuum model for deformation-diffusion in linearized elastic solids. The mathematical model takes into account the affect of the deformation on the diffusion process, and the effect of the transport of an inert chemical species on the deformation of the solid. A robust computational framework is presented for solving the proposed mathematical model, which consists of coupled non-linear partial differential equations. It should be noted that many popular numerical formulations may produce unphysical negative values for the concentration, particularly, when the diffusion process is anisotropic. The violation of the non-negative constraint by these numerical formulations is not mere numerical noise. In the proposed computational framework we employ a novel numerical formulation that will ensure that the concentration of the diffusant be always non-negative, which is one of the main contributions of this thesis. Representative numerical examples are presented to show the robustness, convergence, and performance of the proposed computational framework. Another contribution is to systematically study the affect of transport of the diffusant on the deformation of the solid and vice-versa, and their implication in modeling degradation/healing of materials. It is shown that the coupled response is both qualitatively and quantitatively different from the uncoupled response.