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Fatigue failure of regenerator screens in a high frequency Stirling engineFailure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and on removing the regenator screens, debris of unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 micron thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected it to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.
Document ID
19880015107
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hull, David R.
(NASA Lewis Research Center Cleveland, OH, United States)
Alger, Donald L.
(NASA Lewis Research Center Cleveland, OH, United States)
Moore, Thomas J.
(NASA Lewis Research Center Cleveland, OH, United States)
Scheuermann, Coulson M.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 13, 2013
Publication Date
January 1, 1988
Publication Information
Publication: New Mexico Univ., Transactions of the Fifth Symposium on Space Nuclear Power Systems
Subject Category
Quality Assurance And Reliability
Accession Number
88N24491
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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