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  • 1
    facet.materialart.
    Unknown
    Fiber reinforced superalloys (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Improved performance of heat engines is largely dependent upon maximum cycle temperatures. Tungsten fiber reinforced superalloys (TFRS) are the first of a family of high temperature composites that offer the potential for significantly raising hot component operating temperatures and thus leading to improved heat engine performance. This status review of TFRS research emphasizes the promising property data developed to date, the status of TFRS composite airfoil fabrication technology, and the areas requiring more attention to assure their applicability to hot section components of aircraft gas turbine engines.
    Keywords: COMPOSITE MATERIALS
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Fiber reinforced superalloys (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Improved performance of heat engines is largely dependent upon maximum cycle temperatures. Tungsten fiber reinforced superalloys (TFRS) are the first of a family of high temperature composites that offer the potential for significantly raising hot component operating temperatures and thus leading to improved heat engine performance. This status review of TFRS research emphasizes the promising property data developed to date, the status of TFRS composite airfoil fabrication technology, and the areas requiring more attention to assure their applicability to hot section components of aircraft gas turbine engines.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-89865 , E-3533 , NAS 1.15:89865
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Unknown
    Effect of Prior Air Force over Temperature Operation on Life of J47 Buckets Evaluated in a Sea-level Cyclic Engine Test (1958)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Type: NACA-TN-4263
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Performance of Two Boron-Modified S-816 Alloys in a Turbojet Engine Operated at 1650 F (1959)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: S-816+B and modified S-816+B cast cobalt-base alloys were evaluated as turbine-bucket materials at 16500 F. Stress-rupture and tensile data obtained from these alloys had indicated satisfactory strength for engine operation at 1650 F. Although both alloys exhibited a limited ductility in room-temperature laboratory impact tests, there was a significant increase in impact resistance in the 1650 F tests. Bucket failures began after 10 hours of engine testing and continued at various intervals during the 107.5-hour test. Bucket lives were short relative to the predicted lives based on stress-rupture considerations (280 hr for S-816+B and 1750 hr for modified S-816+B). No significant difference was apparent in the performance of the two alloy groups. The primary cause of bucket failures in both alloys was mechanical fatigue. Impact damage occurred as a direct result of bucket tip fatigue failures and was a secondary cause of bucket failures. The impact of small pieces of fractured bucket tips on surrounding buckets caused a relatively large amount of impact damage to buckets of both alloys. The amount of impact damage from induced fractures at the bucket midspan, which provided relatively large failed fragments, was no greater than that which occurred as a result of tip failures.
    Keywords: Metallic Materials
    Type: NASA-MEMO-3-3-59E , E-229
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Unknown
    Engine Operating Conditions that Cause Thermal-Fatigue Cracks in Turbojet-Engine Buckets (1959)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: Five engine tests were conducted to definitely establish the failure mechanism of leading-edge cracking and to determine which conditions of engine operation cause the failures. Five groups of S-616 and M-252 buckets from master lots were run consecutively in the same J47-25 engine. The tests included a steady-state run at full-power conditions, rapid cycling between idle and rated speed, and three different start-stop tests. The first start-stop test consisted of cycles of start and stop with 5 minutes of idle speed before each stop; the second included cycles of start and stop but with 15 minutes of rated speed before each stop; the third consisted of cycles of gradual starts and normal stops with 5 minutes at idle speed before each stop. The test results demonstrated that the primary cause of leading-edge cracking was thermal fatigue produced by repeated engine starts. The leading edge of the bucket experiences plastic flow in compression during starts and consequently is subjected to a tensile stress when the remainder of the bucket becomes heated and expands. Crack initiation was accelerated when rated-speed operation was added to each normal start-stop cycle. This acceleration of crack formation was attributed to localized creep damage and perhaps to embrittlement resulting from overaging. It was demonstrated that leading-edge cracking can be prevented simply by starting the engine gradually.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-MEMO-4-7-59E , E-281
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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