Skip to main content

FEM simulation of oxidation induced stresses with a coupled crack propagation in a TBC model system

Seiler, Philipp E., Bäker, M., Rösier, J. (2010) FEM simulation of oxidation induced stresses with a coupled crack propagation in a TBC model system. In: IOP Conference Series: Materials Science and Engineering. 9th World Congress on Computational Mechanics and 4th Asian Pacific Congress on Computational Mechanics. IOP Conference Series: Materials Science and Engineering , 10. 012056. IOP Publishing (doi:10.1088/1757-899x/10/1/012056) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:90100)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided.
Official URL
https://doi.org/10.1088/1757-899x/10/1/012056

Abstract

Plasma sprayed thermal barrier coating systems are used on top of highly stressed components, e.g. on gas turbine blades, to protect the underlying substrate from the high surrounding temperatures. A typical coating system consists of the bond-coat (BC), the thermal barrier coating (TBC), and the thermally grown oxide (TGO) between the BC and the TBC. This study examines the failure mechanisms which are caused by the diffusion of oxygen through the TBC and the resulting growth of the TGO. To study the behaviour of the complex failure mechanisms in thermal barrier coatings, a simplified model system is used to reduce the number of system parameters. The model system consists of a bond-coat material (fast creeping Fecralloy or slow creeping MA956) as the substrate with a Y2O3 partially stabilised plasma sprayed zircon oxide TBC on top and a TGO between the two layers. Alongside the experimental studies a FEM simulation was developed to calculate the stress distribution inside the simplified coating system 1. The simulation permits the identification of compression and tension areas which are established by the growth of the oxide layer. Furthermore a 2-dimensional finite element model of crack propagation was developed in which the crack direction is calculated by using short trial cracks in different directions. The direction of the crack in the model system is defined as the crack direction with the maximum energy release rate 2,3. The simulated stress distributions and the obtained crack path provide an insight into the possible failure mechanisms in the coating and allow to draw conclusions for optimising real thermal barrier coating systems. The simulated growth stresses of the TGO show that a slow creeping BC may reduce lifetime. This is caused by stress concentration and cracks under the TGO. A slow creeping BC on the other hand reduces the stresses in the TBC. The different failure mechanisms emphasise the existence of a lifetime optimum which depends on the creep properties of the used bond-coat material. Experimental results show a good agreement with the predicted failure mechanisms.

Item Type: Conference or workshop item (Proceeding)
DOI/Identification number: 10.1088/1757-899x/10/1/012056
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Engineering and Digital Arts
Depositing User: Amy Boaler
Date Deposited: 09 Sep 2021 11:35 UTC
Last Modified: 16 Nov 2021 10:27 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/90100 (The current URI for this page, for reference purposes)
  • Depositors only (login required):