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Fatigue Failure Criteria for Single Crystal Nickel SuperalloysHigh Cycle Fatigue (HCF) induced failures in aircraft gas-turbine and rocket engine turbopump blades is a pervasive problem. Single crystal turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry and NASA because of their superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys. Single-crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the pan geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades is complicated to predict due to the material orthotropy and variations in crystal orientations. A fatigue failure criteria based on the maximum shear stress amplitude [delta t max] on the 30 slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criteria reduces the scatter in uniaxial LCF test data, for four different specimen orientations, for PWA 1484 at 1200 F in air, quite well. A power law curve fit of the failure parameter, delta t max, vs. cycles to failure is presented.
Document ID
20020043309
Acquisition Source
Marshall Space Flight Center
Document Type
Other
Authors
Arakere, Nagaraj K.
(Florida Univ. FL United States)
Date Acquired
August 20, 2013
Publication Date
October 1, 1999
Publication Information
Publication: 1999 NASA/ASEE Summer Faculty Fellowship Program
Subject Category
Metals And Metallic Materials
Funding Number(s)
CONTRACT_GRANT: NGT8-52874
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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