Vol. 1, No. 2, pp. 55-64 (2005)
THE EFFECTS OF ELASTO-PLASTIC BEHAVIOR AT THE CRACK TIP ON
FATIGUE CRACK PROPAGATION
Y. Xiong1 J. Katsuta2,* K. Kawano2 T. Sakiyama2
1Graduate School of Science and Technology, Nagasaki University,
1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
2Department of Structural Engineering, Faculty of Engineering, Nagasaki University,
1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
(*Corresponding author:This email address is being protected from spambots. You need JavaScript enabled to view it.">This email address is being protected from spambots. You need JavaScript enabled to view it. )
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ABSTRACT
Emphasis on physical meanings of the hysteresis loop denoting the relationship between loads and strainsnear the crack tip, variations of the loading tensile plastic load zone and the unloading compressive plastic load zone are studied respectively under various fatigue test conditions, and the effects on acceleration, deceleration and non-propagation during fatigue crack propagation are also studied. Two types of crack closure are obtained from tests, and the influence of each load zone of the hysteresis loop on fatigue crack propagation is evaluated. Result shows that load zones PRPG~Pmax and PRCPG~PCF play an important role in the crack opening/closure behavior, and the fatigue crack propagates difficultly if the compressive plastic zone at the crack tip is not enough.
KEYWORDS
Fatigue crack propagation, Crack tip, Opening/closure, Hysteresis loop, compressive plastic zone, Variable amplitude loading
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