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2 International Journal of Applied Mechanics and Engineering

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Parametric studies of failure mechanisms in thermal barrier coatings during thermal cycling using FEM

Srivathsa B., Das D. K.

International Journal of Applied Mechanics and Engineering

2015

Vol. 20, no. 4

899--915

Thermal barrier coatings (TBCs) are widely used on different hot components of gas turbine engines such as blades and vanes. Although, several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are developed during the thermal cycling. In the present study, the residual stress build-up in an electron beam physical vapour deposition (EB-PVD) based TBCs on a coupon during thermal cycling has been studied by varying three parameters such as the cooling rate, TBC thickness and substrate thickness. A two-dimensional thermomechanical generalized plane strain finite element simulations have been performed for thousand cycles. It was observed that these variations change the stress profile significantly and the stress severity factor increases non-linearly. Overall, the predictions of the model agree with reported experimental results and help in predicting the failure mechanisms.

Modeling of residual stresses developed in thermal barrier coatings during thermal cycling

Srivathsa B., Alam M. Z., Kamat S. V., Das D. K.

International Journal of Applied Mechanics and Engineering

2011

Vol. 16, no 3

869-883

Thermal barrier coatings (TBCs) are widely used on Ni-based superalloy components of gas turbine engines. Although several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are introduced due to the growth of the TGO during operation. In the present study, the residual stress build-up in a TBC system during thermal cycling is modeled. A two-dimensional plane strain finite element analysis is carried out. The model includes both flat and undulated growth fronts for the TGO layer. The stress distribution pattern in the TBC system in the case of a planar TGO front was found to be markedly different from that of an undulated front. The ceramic layer was found to be prone to delamination at concave undulations.