STP1321: Fatigue Crack Growth in the Highly Plastic Regime

    Kim, KS
    Professor and Graduate student, Pohang University of Science and Technology, Pohang,

    Baik, YM
    Professor and Graduate student, Pohang University of Science and Technology, Pohang,

    Pages: 14    Published: Jan 1997


    Abstract

    This paper evaluates the performance of ΔJ*, ΔJ∧ and ΔK as fracture parameters for center-cracked plate specimens of Alloy 718 under Rσ=0, nominally elastic and plastic loading at elevated temperatures. The parameters ΔJ* and ΔJ∧ are computed from the results of an elastic-plastic finite element analysis of crack growth. At 538°C the results show, in contrast to the previous results of Rε=-1 strain control tests, that the correlation of crack growth rates with ΔJ* or ΔJ∧ deviates from the relation of the Paris law type while ΔK gives a satisfactory correlation. The correlation at 649°C is poor for all three parameters. The finite element analysis shows that the crack closing behavior diminishes and eventually disappears as the crack tip plasticity increases due to crack growth or increased applied stress.

    Keywords:

    integral parameters, stress intensity factor, Alloy 718, crack growth, crack closure


    Paper ID: STP12322S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP12322S


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