| 摘要 |
PURPOSE:To make it possible to control stress in a cracked tip part, by measuring the amunt of progress of cracks in synchronization with the phase of a load by using surface waves caused by ultrasonic waves, when the fatigue test of a test piece having a cut-out part is performed. CONSTITUTION:Repeating loads are imparted to a test piece 1 having a cut-out part 1b by an actuator 3 with the amplitude being controlled by a load-amplitude controlling part 11, and cracks are yielded. A pair of ultrasonic wave probes 5a and 5b, which transmits and receives ultrasonic waves, is attached to the side of the cut-out part 1b of the test piece 1. The probes receive a load amplitude signal from a load cell 4 and transmit/receive 5a and 5b the signal of an ultrasonic-wave oscillator 6, which is synchronized with the phase of the load. The propagating time at the maximum load is measured by a time measuring part 7, and the propagating time is stored in a memory part 8. An operating part 9, which outputs a control signal to the load-amplitude controlling part 11, is provided, so that the load amplitude is controlled in correspondence with the propagating time from the memory part 8 at the time of no load, time difference at the maximum load, and stress expanding coefficient from an initial- value setting device 10. |
