Multi-Mechanism Synergy in Variable-Amplitude Fatigue

    Volume 1, Issue 10 (November 2004)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 1 November 2004

    Page Count: 21


    Sunder, R
    BiSS Research, Bangalore,

    Ashbaugh, NE
    University of Dayton Research Institute, Dayton, OH

    Porter, WJ
    University of Dayton Research Institute, Dayton, OH

    Rosenberger, AH
    Air Force Research Laboratory (AFRL/MLLN), Wright-Patterson AFB, OH

    (Received 12 July 2002; accepted 12 November 2003)

    Abstract

    Fractographic studies on Al alloys and a nickel-base super-alloy point to the combined action of three major load-interaction mechanisms in controlling crack growth under variable-amplitude loading. These are crack closure, residual stress, and crack front incompatibility. Crack front incompatibility attenuates crack tip response to applied load and can also increase crack closure stress. Notch root residual stress affects crack closure, while crack tip residual stress moderates environment-enhanced fatigue crack extension. The latter effect disappears in vacuum. Experiments designed to isolate the effect of individual mechanisms provide a framework to model their synergistic action, consistent with microscopic observations of crack growth bands in variable amplitude fatigue.


    Paper ID: JAI19065

    DOI: 10.1520/JAI19065

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    Author
    Title Multi-Mechanism Synergy in Variable-Amplitude Fatigue
    Symposium Fatigue Testing and Analysis Under Variable Amplitude Loading Conditions, 2002-05-31
    Committee E08