The fatigue life prediction method by electromagnetic ultrasonic resonance method

摘要

PROBLEM TO BE SOLVED: To accurately grasp the change within a material in a fatigue process to evaluate remaining life at the initial stage of a fatigue advance process by generating burstlike ultrasonic resonation in an object to be measured by an electromagnetic ultrasonic transducer. ;SOLUTION: In an electromagnetic ultrasonic transducer 1, when a permanent magnet 2 of the like forms a static magnetic field 11 in the depth direction of an object 30 to be measured and a high frequency burst wave current is allowed to flow to a plane coil 3 from a controller 6, ultrasonic traversal waves 15 are generated. The ultrasonic traversal waves repeat reflection within the object 30 to be measured to generate burst like ultrasonic resonation. The eddy current 19 by the reflected ultrasonic waves is detected by the plane coil 3 and this detection signal is amplified by a preamplifier 4 and a main amplifier 5 to be sent to a computer 40 through the controller 6. A fatigue advance process is monitored while referring to the data base of the attenuation curve preliminarily stored in the computer 40. That is, life is measured by utilizing the behavior of the peak of the attenuation curve.;COPYRIGHT: (C)1997,JPO