Journal Published Online: 01 January 2004
Volume 32, Issue 1

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



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
University of the Ryukyus, 1 Nishihara, Okinawa, Japan
Purnowidodo, Anindito
University of the Ryukyus, 1 Nishihara, Okinawa, Japan
Sueyoshi, Toshiyasu
University of the Ryukyus, 1 Nishihara, Okinawa, Japan
Utsunomiya, Takao
Shibaura Institute of Technology, Tokyo, Japan
Pages: 6
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Stock #: JTE11853
ISSN: 0090-3973
DOI: 10.1520/JTE11853