Finite Element Simulation Study On Material Parameters, Interface Porosity And Roughness Of Internal Stress In Thermal Barrier Coatings

With the development of modern aerospace, the use temperature of hot-end components is increasing and the work environment is rigor. High temperature oxidation of metals became one of the most important factor to influence the lifetime of hot-end components. High temperature oxidation is a main factor of the TBCs failure. TGO will emerge internal stress during the application and the accumulation of the internal stress would bring in crack which made the specimen fail. But for now, the specimen’s micro-structure can only be analysis under the transient room temperature, the change of internal stress cannot be measured in a dynamic environment. Considering the complexity of the interface topography of the coating, the internal stress and the crack cannot be measure in dynamic. So the professional finite element software would be used to simulate complex application environment.This article focuses on TBCs produced by APS. Finite element software ANSYS Workbench was adopted to simulate. Influence of Interface roughness, porosity, the size of the pore and its distribution on residual stress which were analysis systematically.A modeling software is used to build a model of TBCs which include bond coating(BC),thermally grown oxide (TGO) and ceramic layer. The distribution of the stress field which is influenced by physical parameter and interfacial parameter(the amplitude and the wavelength)can be researched. Simulation result display:each layer will get different stress distribution through changing the thermal expansions of the bond coating, TGO and ceramic layer. Low coefficient of thermal expansion create a larger stress. This provide the requirement of tensile stress in the interface of oxidation layer and bonding layer. Furthermore, crack will grow at this place. Increase the young modulus of the ceramic layer, the stress of deformation will also increase. All this will result in the increase of rigidity. Above all,the stress reduce when the curvature of the ellipse decreases. The only shortcoming of the semi-ellipse is the tensile stress growing and extending.Based on the roughness of the interface, change the porosity, size and position. Simulated result display:same form, different porosity, with the increase of porosity, The peak stress increase in the beginning. But when it increased to a certain extent, The peak will decrease.Different porosity, size and position influence to stress shows, under void content condition, elliptical The peak stress is decreasing, other two feature indefinite.it arise more elliptical interface topography at the prepare TBCs, experimental verification geometrical morphology and porosity has influence to coating stress. Simulated result is identical to the experiment.