Open Access

ABSTRACT

Indentation Analysis of a Multi-Layered Hollow Cylinder for the Measurement of Interfacial Toughness in TBC Systems

by Q. Ma¹, J. L. Beuth¹, G. H. Meier³, F. S. Pettit³

1 Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA. Now with EFC School of Engineering, Walla Walla University, College Place, WA 99324, USA
2 Now with EFC School of Engineering, Walla Walla University, College Place, WA 99324, USA
3 Department of Mechanical Engineering & Materials Science, University of Pittsburgh, PA 5261, USA

The International Conference on Computational & Experimental Engineering and Sciences 2008, 8(1), 13-18. https://doi.org/10.3970/icces.2008.008.013

Abstract

This paper addresses the mechanics of indentation-induced delamination of a coating on a multi-layered hollow cylinder, for application to toughness testing of thermal barrier coating (TBC) systems. An electron-beam physical vapor deposition (EB-PVD) TBC system has been analyzed through a contact finite element model using a standard conical indenter impressed vertically on the top of the cylinder. Two cylinder sizes used in thermal-mechanical fatigue tests in literature have been considered in the analysis, with outer radii of 5.11 mm and 3.08 mm, and inner radii of 3.00 mm and 0.97 mm, respectively. Two boundary conditions for the inner surface of each cylinder, traction free and constrained radial displacement, have been considered in the numerical studies. It is shown that stress intensity factor distributions in the axial direction on the cylinder surface are close to corresponding 2-D results for the indent test load levels of interest. Consequently, with regard to the measurement of interfacial toughness, the complex 3-D analysis can be understood using 2-D simulation results. At the same time, 3-D results are also found to be important in identifying valid indentation tests avoiding buckling driven delamination.

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