Chapter 23. Analysing the Failure Behaviour of Thermal Barrier Coatings Using the Finite Element Method

  1. Todd Jessen and
  2. Ersan Ustundag
  1. Kais Sfar,
  2. Jarir Aktaa and
  3. Dietrich Munz

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294628.ch23

24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 21, Issue 3

24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 21, Issue 3

How to Cite

Sfar, K., Aktaa, J. and Munz, D. (2000) Analysing the Failure Behaviour of Thermal Barrier Coatings Using the Finite Element Method, in 24th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 21, Issue 3 (eds T. Jessen and E. Ustundag), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294628.ch23

Author Information

  1. Institute for Materials Research II Forschungszentrum Karlsruhe GmbH P.O. Box 3640, D-76021 Karlsruhe, Germany

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2000

ISBN Information

Print ISBN: 9780470375686

Online ISBN: 9780470294628

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Keywords:

  • microcrack propagation behavior;
  • polycrystalline alumina;
  • residual stress field;
  • in-situ observation;
  • electron back scattered diffraction

Summary

The plasma-sprayed zirconia-8-yttria-based Thermal Barrier Coating (TBC) is exposed to thermal cyclic fatigue. Due to thermal expansion mismatch and oxidation of the bond coat, high residual stresses are induced, leading to failure by spalling and delamination. The finite element method has been used in order to obtain detailed stress distributions in TBC systems. Several geometrical configurations of bond coat and oxide layer were modelled to promote micromechanical understanding of the failure behaviour of the two-layer system. The roughness of the interface between bond coat and oxide layer was also taken into account. Thermal stresses due to thermal expansion mismatch and expansion stresses by a high-temperature oxidation of the bond coat were then calculated. The analysis was performed using different material laws considering the elastic, elastic-plastic, and viscoplastic behaviour of the different layers. A blunted crack was implemented in a four-layer TBC structure and the condition of crack propagation was discussed. The fracture mechanical assessment was performed using the J-Integral concept. On the basis of the results gained, a failure model for TBC systems was derived.