STP924

    The Propagation of Short Fatigue Cracks at Notches

    Published: Jan 1988


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    Abstract

    Center-notched plate specimens and single-edge-notched specimens of a low-carbon steel were fatigued under axial and bending loads. The growth behavior of a short fatigue crack near the notch tip was analyzed based on the measurement of crack closure. The crack closure develops as a crack grows; the effective fraction of the applied stress decreases. This accounts for the decrease of the crack growth rate with increasing crack length. The relation between growth rate and the effective stress intensity range is unique, and nearly identical to that for a long crack, meaning that the effective stress intensity range is a good measure of the crack driving force. The results on the threshold of crack growth are compared with the model proposed by Tanaka and Nakai. The variations of the threshold values of the stress intensity range and the effective stress intensity range, and the crack closure at the threshold with the length of nonpropagating cracks, agree well with the model prediction.

    Keywords:

    fatigue (materials), notch, short crack, crack closure, fracture mechanics, low-carbon steel, grain size, threshold condition, fatigue limit


    Author Information:

    Tanaka, K
    Associate professor and graduate student, Kyoto University, Kyoto,

    Akiniwa, Y
    Associate professor and graduate student, Kyoto University, Kyoto,


    Paper ID: STP23221S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP23221S


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