Volume 32, Issue 1 (January 2004)

    Detecting Overload from Strain Information during Fatigue Crack Propagation under Negative Stress Ratio

    (Received 6 February 2003; accepted 9 July 2003)

    CODEN: JTEOAD

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    Abstract

    In the present study, a detection method of an overload application during stress cycles under constant amplitude was investigated. Also, the effect of the tensile overload was shown at three stress ratios: R = 0, -1, and -1.5, to understand the effects of R on crack propagation after an overload. At the baseline of R = 0, after the overload, retardation in the crack propagation was observed, and the crack growth rate decreased. However, in the case of R = -1.5, the fatigue crack growth rate actually accelerated after the tensile overload. The detection of that crack propagation behavior was attempted through the information of the strain waveform h; h = εy + 1.2λx, where εx and εy are the local strains at the specimen axis, and λ is the strain range ratio Δεy/Δεx. The waveform shape of h was changed after the overloading. Also, the application of the overload could be detected by the variation of the strain range ratio λ. Especially, the present method is useful for cases of the crack propagation stage under negative R conditions.


    Author Information:

    Makabe, Chobin
    Professor, Graduate Student, and Lecturer, University of the Ryukyus, 1 Nishihara, Okinawa

    Purnowidodo, Anindito
    Professor, Graduate Student, and Lecturer, University of the Ryukyus, 1 Nishihara, Okinawa

    Sueyoshi, Toshiyasu
    Professor, Graduate Student, and Lecturer, University of the Ryukyus, 1 Nishihara, Okinawa

    Utsunomiya, Takao
    Professor, Shibaura Institute of Technology, Tokyo,


    Stock #: JTE11853

    ISSN: 0090-3973

    DOI: 10.1520/JTE11853

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    Author
    Title Detecting Overload from Strain Information during Fatigue Crack Propagation under Negative Stress Ratio
    Symposium , 0000-00-00
    Committee E08