DIFFUSION CREEP ANALYSIS IN PEROVSKITE THICK-WALLED CYLINDER UNDER RADIAL OXYGEN VACANCIES GRADIENT

In the present paper, the nonlinear problem of diffusion creep and stress evolution has been formulated for tubular perovskite-type membranes of a high-temperature catalytic membrane reactor. For this purpose, the impact of point defects (oxygen vacancies) and volume microstructural defects (voids) of perovskites on the creep deformation of a thick-walled hollow cylinder is analysed at high temperatures and under generalized plane strain in conditions of radial oxygen vacancies gradient. Transport of oxygen vacancies through the membrane thickness is described by Fick's second law. The constitutive equation of diffusion creep and damage evolution equation for voids have been specified for perovskites under complex stress state. The analytical-numerical method has been discussed for solving the initial-boundary value problems of the diffusion creep for thick-walled hollow cylinder, taking into account damage development in a form of oxygen vacancies and voids. An example of creep analysis of perovskite-type thick-walled hollow cylinder is considered under radial oxygen vacancies gradient and, additionally, under radial temperature gradient with the assessment of its long-term strength.