PROBLEM TO BE SOLVED: To non-destructively evaluate a fatigue damage progress behavior during a high cycle fatigue test at a liquid nitrogen temperature (77 K) and to evaluate the occurrence of fatigue damage, a progress mechanism, and crack occurrence like in addition to fracture life.;SOLUTION: Liquid surface height of liquid nitrogen is controlled, vibrations of a specimen end part in a cryostat in which mist is prevented from penetrating into a laser optical path are detected by a laser vibration meter, a continuous waveform is recorded, and a nonlinear ultrasonic wave and AE are simultaneously analyzed.;COPYRIGHT: (C)2013,JPO&INPIT
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