STP791

    On the Relation Between the Threshold and the Effective Stress-Intensity Factor Range During Complex Cyclic Loading

    Published: Jan 1983


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    Abstract

    Overload effects have been studied for center-cracked tension (CCT) specimens of aluminum alloy 2124-T351. The results show that the retardation of crack propagation due to overloading, which is not taken into account by the Paris relation, can be explained by variation in the U ratio as defined by Elber. The crack length over which this retardation occurs was found equivalent to the diameter of the plastic zone as calculated by the Irwin relation. It was verified that the minimum value of ΔKeff reached after overloading could be calculated from threshold measurements taking into account the loading history. The threshold after overloading was related to the overload ratio, implying that two kinds of tests are sufficient to determine the threshold after any overload ratio and hence the minimum ΔKeff. The relationship between ΔKeff and the plastic zone size gives the ΔKeff value for a given crack length in the affected zone without measurement of crack tip opening displacement.

    Keywords:

    aluminum alloys, effective stress-intensity factor range, threshold, R-ratio influence, overloading effects, spectrum loadings, prediction of retardation, fracture mechanics


    Author Information:

    Bertel, JD
    Research assistant, research assistant, and professor of Engineering Mechanics, University of Technology,

    Clerivet, A
    Research assistant, research assistant, and professor of Engineering Mechanics, University of Technology,

    Bathias, C
    Research assistant, research assistant, and professor of Engineering Mechanics, University of Technology,


    Paper ID: STP37082S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37082S


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