STP714: Effects of Gas Turbine Engine Load Spectrum Variables on Crack Propagation

    Macha, DE
    Materials engineers, Air Force Materials Laboratory, Wright-Patterson Air Force Base, Ohio

    Grandt, AF
    Materials engineers, Air Force Materials Laboratory, Wright-Patterson Air Force Base, Ohio

    Wicks, BJ
    Aeronautical Research Laboratories, DSTO, Melbourne,

    Pages: 20    Published: Jan 1980


    Abstract

    This paper describes results of an elevated temperature fatigue crack growth study in IN-100, a nickel-base superalloy. The objective of this study was to determine if conventional fracture mechanics techniques can predict crack growth under conditions expected to occur in jet engine turbine disks. Results are reported for two types of experiments. The first group of tests examines isolated load events that may occur in a turbine disk load history. The influence of tensile overloads, compressive underloads, overload/underload sequences, and periods of sustained load on subsequent constant amplitude fatigue crack growth are discussed. The second group of specimens was subjected to a spectrum load history that combines many of the isolated load events. Cumulative damage crack growth predictions are performed by several procedures and shown to agree quite well with the experimental results. The influence of specimen thickness is considered for both the isolated event and the spectrum loading experiments.

    Keywords:

    fatigue crack growth, fatigue (materials), spectrum loading, elevated temperature, retardation, load interactions, sustained loading, nickel-base superalloy, life predictions, cumulative damage, crack propagation


    Paper ID: STP27485S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP27485S


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