Oxidation induced stress fields in an EB-PVD thermal barrier coating

An elastoviscoplastic analysis based on the finite element method is proposed for the calculation of stress fields responsible for the spallation of an electron beam physical vapor deposition thermal barrier coating. Computations of the mechanical behavior are coupled to a diffusion model to reproduce the growth of the oxide scale. A periodic unit cell, characterizing the local microstructure, is used to compute stress fields at the bond-coat/oxide interface as a function of the interfacial roughness, oxidation time and growth stress. Results show a good agreement between experimental observations of crack locations and calculated spallation stress at the oxide/bond-coat interface.