PSI - Issue 22

Andrey Burov et al. / Procedia Structural Integrity 22 (2019) 243–250

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

4. Conclusions The finite element modelling has been employed to study interface cracking behaviour in a thermal barrier coating on a single-crystal Ni-based superalloy. The cohesive zone elements have been implemented in the model to simulate interfacial debonding between the TC, TGO and BC layers. To evaluate the effect of the interface geometry on the residual stress state and cracking behaviour, two cases of the TGO profile have been analysed: a regular sinusoidal undulation with constant thickness and an irregular (unevenly thicker) TGO layer with symmetrical penetrations into the TC and BC layers. The case with the regular TGO layer appears to be a more dangerous in terms of interface failure than that one with the irregular TGO shape. This, to some extent, contradicts the experimental data that the spallation of the top coat has been observed near the oxide irregularity. The other (than delamination) mechanisms could be responsible for such TBC failure. For instance, the high compressive stresses in the TGO might cause buckling of the layer if cracks formed at the interfaces are reached the critical length. Also, the coalescence of the interfacial cracks and cracks within the TC and TGO layers as another failure mechanism should not be excluded. This is the subject for the upcoming research. References Alfano, G., Crisfield, M.A., 2001. Finite element interface models for the delamination analysis of laminated composites: Mechanical and computational issues. International Journal for Numerical Methods in Engineering 50, 1701 – 1736. ANSYS Academic Research, Release 17.0, Help System (ANSYS Inc., 2016) Bäker, M., 2012. Finite element simulation of interface cracks in thermal barrier coatings. Computational Materials Science 64, 79 – 83. Białas , M., 2008. Finite element analysis of stress distribution in thermal barrier coatings. Surface and Coatings Technology 202, 6002 – 6010. Cen, L., Qin, W.Y., Yu, Q.M., 2019. 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