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Experimental and analytical study of ceramic-coated turbine-tip shroud seals for small turbine enginesThe results of an experimental and analytical evaluation of ceramic turbine tip shrouds within a small turbine engine operating environment are presented. The ceramic shrouds were subjected to 1001 cycles between idle and high power and steady-state conditions for a total of 57.8 engine hr. Posttest engine inspection revealed mud-flat surface cracking, which was attributed to microcracking under tension with crack penetration to the ceramic and bond coat interface. Sections and micrographs tend to corroborate the thesis. The engine test data provided input to a thermomechanical analysis to predict temperature and stress profiles throughout the ceramic gas-path seal. The analysis predicts cyclic thermal stresses large enough to cause the seal to fail. These stresses are, however, mitigated by inelastic behavior of the shroud materials and by the microfracturing that tensile stresses produce. Microfracturing enhances shroud longevity during early life but provides the failure mechanism during life but provides the failure mechanism during extended life when coupled with the time dependent inelastic materials effects.
Document ID
19850009748
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Biesiadny, T. J. (NASA Lewis Research Center Cleveland, OH, United States)
Mcdonald, G. E. (NASA Lewis Research Center Cleveland, OH, United States)
Hendricks, R. C. (NASA Lewis Research Center Cleveland, OH, United States)
Little, J. K. (NASA Lewis Research Center Cleveland, OH, United States)
Robinson, R. A. (AVSCOM Research and Technology Labs Cleveland, Ohio, United States)
Klann, G. A. (AVSCOM Research and Technology Labs Cleveland, Ohio, United States)
Lassow, E. S. (Howmet Turbine Components Corp. Whitehall, Mich., United States)
Date Acquired
September 5, 2013
Publication Date
January 1, 1985
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NASA-TM-86881
NAS 1.15:86881
USAAVSCOM-TR-84-C-19
E-2343
Accession Number
85N18057
Funding Number(s)
PROJECT: RTOP 505-40-5A
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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