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Effect of Random Thermal Spikes on Stirling Convertor Heater Head ReliabilityOnboard radioisotope power systems being developed to support future NASA exploration missions require reliable design lifetimes of up to 14 yr and beyond. The structurally critical heater head of the high-efficiency developmental Stirling power converter has undergone extensive computational analysis of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Additionally assessment of the effect of uncertainties in the creep behavior of the thin-walled heater head, the variation in the manufactured thickness, variation in control temperature, and variation in pressure on the durability and reliability were performed. However, it is possible for the heater head to experience rare incidences of random temperature spikes (excursions) of short duration. These incidences could occur randomly with random magnitude and duration during the desired mission life. These rare incidences could affect the creep strain rate and therefore the life. The paper accounts for these uncertainties and includes the effect of such rare incidences, random in nature, on the reliability. The sensitivities of variables affecting the reliability are quantified and guidelines developed to improve the reliability are outlined. Furthermore, the quantified reliability is being verified with test data from the accelerated benchmark tests being conducted at the NASA Glenn Research Center.
Document ID
20050060622
Acquisition Source
Glenn Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Shah, Ashwin R.
(Sest, Inc. Middleburgh Heights, OH, United States)
Korovaichuk, Igor
(Sest, Inc. Middleburgh Heights, OH, United States)
Halford, Gary R.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 22, 2013
Publication Date
January 1, 2004
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
E-14918
Meeting Information
Meeting: International Energy Conversion Engineering Conference
Location: Providence, RI
Country: United States
Start Date: August 16, 2004
End Date: August 19, 2004
Funding Number(s)
OTHER: 972-20-01
Distribution Limits
Public
Copyright
Public Use Permitted.
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