Dual-horizon peridynamics modeling of coupled chemo-mechanical-damage for interface oxidation-induced cracking in thermal barrier coatings

The interface oxidation-induced cracking process in thermal barrier coatings (TBCs) is rather complex. It involves the material changes of chemical reactions, dynamic migration and diffusion of BC/TGO (bond coat/thermally grown oxide) interface, delamination of TC (top coat)/TGO and BC/TGO interfaces, multiple delamination cracks and their interactions within the TGO layer, etc. The complex process presents significant difficulties and challenges to simulation. To explore the comprehensive cracking mechanisms induced by the interface oxidation, we propose the coupled chemo-mechanical-damage model in a dual-horizon peridynamic framework (CMD-DHPD). The corresponding governing equations and their linearized forms are derived in the form of integral coupled equations for CMD-DHPD. The dual-horizon peridynamic diffusion-reaction equation and its linearization are derived based on the dual-horizon peridynamic correspondence principle. The nonlocal crack phase-field and interface phase-field are presented to address the geometric discontinuity of bulk materials and the material discontinuity in the region of the TC/TGO interface, respectively. In order to ensure convergence and accuracy, the BFGS Quasi-Newton algorithm is further enhanced to solve for the integral equations arising from the coupled chemo-mechanical-damage processes. The proposed CMD-DHPD captures the TGO growth pattern, interface cracks initiation, propagation and their interactions as observed in experiments. Therefore, it is extremely suitable for solving the interface oxidation-induced cracking process in thermal barrier coatings.