ISSN: 1945-7553
CODEN: JTEVAB
Published Online: 30 April 2007
Page Count: 6

Crack Growth Behavior in Overloaded Specimens with Sharp Notch in Low Carbon Steel

Purnowidodo, Anindito
Lecturer, Mechanical Engineering Department, Brawijaya University, JI. MT. Halang, East Java

Fukuzato, Shingo
Technician, Okinawa Electric Power Co., Urasoe-city, Okinawa

Saimoto, Akihide
Associate Professor, Graduate School of Science and Technology, Nagasaki University, Nagasaki-city, Nagasaki

Makabe, Chobin
Professor, Department of Mechanical and Systems Engineering, University of the Ryukyus, Okinawa

(Received 13 June 2005; accepted 15 February 2007)

Abstract

The purpose of the present study is to evaluate fatigue crack propagation after tensile overloading. A 6-mm long u-shaped notch was cut in the center section of the specimen. Notch root radii of 0.1, 1, and 2 mm were chosen for ρ. These were regarded as center-notched specimens. The crack propagation behavior of these specimens was compared with a center-cracked specimen. Push-pull fatigue tests were carried out under stress ratios R=0, −1, and −1.5. A special investigation was made into the results for ρ=1 mm. After overload, retardation of crack growth was observed under R=0 and −1 for the notched specimens and center-cracked specimens. However, where R=−1.5, crack growth acceleration was observed after overload in both types of specimens. Even though crack growth was accelerated or decelerated, the rate was able to be evaluated by the effective stress intensity factor range after 0.2 mm of crack growth from the notch root.

Keywords:
fatigue crack propagation, overload, stress ratio, notched specimen, stress intensity factor

Paper ID: JTE100097
DOI: 10.1520/JTE100097
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