Abstract
It has been acknowledged that stresses within a thermal barrier coating (TBC) and its durability are significantly affected by the coating interfaces. This paper presents a finite element approach for stress analysis of the plasma sprayed TBC system, using three-dimensional (3D) coating interfaces. 3D co-ordinates of the coating surfaces were measured through 3D reconstruction of scanning electron microscope (SEM) images. These co-ordinates were post processed to reconstruct finite element models for use in stress analyses. A surface profile unit cell approach with appropriate boundary conditions was applied to reduce the problem size and hence computation time. It has been shown that for an identical aspect ratio of the coating interface, interfacial out-of-plane stresses for 3D models are around twice the values predicted using 2D models. Based on predicted stress development within the systems, possible crack development and failure mechanisms of the TBC systems can be predicted.
Highlights
Thermal barrier coating (TBC) systems are applied onto various superalloy and metal components e.g. gas turbine blades of an aircraft, diesel engine combustion chambers etc
It was found that when the 3D model was employed, the maximum tensile out-of-plane stresses at the thermally grown oxide (TGO)/TBC interface increased by a factor of nearly two
Similar findings were presented by Gupta, et al [18] and Glynn et al [40]. These findings illustrate the importance of employing 3D models while carrying out stress analyses for TBC systems to avoid the underestimation of stresses caused through the use of a 2D profile
Summary
Thermal barrier coating (TBC) systems are applied onto various superalloy and metal components e.g. gas turbine blades of an aircraft, diesel engine combustion chambers etc. Kyaw et al / Materials and Design 125 (2017) 189–204 components of land-based gas turbine engines For this system, the surface roughness of the BC provides a mechanical bond to the TC and influences its lifetime [1]. Computational tools (such as object oriented finite element or OOF2 [13]) transform micrograph images into FE meshes to be used for further FE analyses The application of this method for stress analysis of the TBCs can be found in Ref. This work fits into the present Journal's priority area [21] of the analysis, structure, morphology and role of interfaces in the context of multi-physics phenomena, by describing the influences of manufacturing-related interface geometry on the development of stresses and cracks due to thermo-mechanical and oxidation effects. This paper documents the development of a theoretical model of interface stress with the use of experimental data of interface geometry which can be used in the design of future turbine blade coatings
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