Abstract
Vibrating reed machine to thin plate fatigue test is a kind of resonance type, invented by Hirata 1995 as the method of a speaker unit was used as the vibrator. In the case of the fatigue evaluation of thin plate plane bending stress as typified by bellows are needed, it was expected as the effectual method. There are little research papers that made adequacy evaluations about absolute level of fatigue data. Furthermore, even though the test method is high-speed and simple, it doesn't become universal. And so, this paper is appeared to make adequacy evaluations of thin plate vibrating reed fatigue test with testing thin test pieces actually. In this time, adding the determined points of the displacement, and using a vibration exciter, accuracy is increased. Vibrating reed fatigue tests were carried out for Inconel 718 in ambient air using 5 mil and 8 mil notched specimens with 64 Hz and 110 Hz. Fatigue results appeared that the fatigue strength in vibration reed method was higher than that in rotating bending fatigue tests with 55 Hz reported by Kawagoishi et al. 2006. Then pointing out the stress field of crack tip in the difference of thickness, the calculations of each stress intensity factor conduced to the effect of thickness. The increase in fatigue strength of thin plate was caused by the reduction of stress intensity factor in the crack tip with early crack growth.
