抄録
To clarify the effect of stress biaxiality on the fatigue crack growth rate, biaxial (torsional) and uniaxial fatigue crack propagation tests were carried out on a mild carbon steel. The torsional fatigue tests were performed using the tubular specimens with an initial slit 45°-inclined to the specimen axis. The behavior of fatigue crack closure was measured in each test by means of an unloading elastic compliance method. In the biaxial fatigue, the crack growth rate was faster under pulsating loading than under fully reversed loading, when the results were compared by using a parameter of usual cyclic stress intensity factor range ΔK. This difference in crack growth rate disappeared when the data were characterized in terms of a parameter of effective cyclic stress intensity factor range ΔKeff. Furthermore, it was found that the crack growth rate is faster under biaxial stressing than under uniaxial stressing.
