Instrumented indentation has been suggested as a method to determine interfacial fracture toughness of thermal barrier coatings. However, in a previous experimental study we showed that the results are ambiguous. In this work, we investigate the experimental results by numerical simulations incorporating the material microstructure. In the numerical simulations, based on finite element analyses, the stress fields that are associated with the loading and unloading of the indenter are investigated. By comparing these stress fields to the damage observed in the experimental study, including crack path and interfacial delaminations, we explain key findings from the experimental observations. Our results suggest that indentation testing of multilayered coated structures might not induce the delamination in the overall weakest interface and therefore the test results must be evaluated with care. © 2008 Elsevier B.V. All rights reserved.
Bibliographical noteThe authors acknowledge the financial support by the National Science Foundation, DMR-0346664 and the Office of Naval Research ONR-N00014-04-1-0498 (JY and AMK), the European Community’s Human Potential Program under contract HPRN-CT-2002-00203 [SICMAC] (MB), and NSF CMS-0407743 (XC).
- Interfacial fracture toughness
- Multilayered coatings
- Numerical simulations
- Thermal barrier coatings (TBC)