A STUDY OF NONDESTRUCTIVE TESTING WITH MAGNETIC CHARACTERISTIC MEASUREMENT METHOD

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In this research, I investigated that establishment of a method estimate the metals fatigue as its object by measuring the magnetic characteristics. A single sheet tester method by using H-coil method is investigated. Originally, it needs to measure a fatigue with using condition. But this study for the purpose of obtain the fundamental date, so produce the equipment which can measure the single sheets that size are 40**140mm.The plot-type single sheet tester with double-yoke vertical was made. Magnetic flux density was measured by B-coil, and magnetic field intensity was measured by H-coil.The fatigue was given by the equipment which was made by us. The one side of the sample is fixed and another side was vibrated by the equioment. the frequency of the vibration is about 5 to 10 Hz. The number of frequent is counted by bounter.Measurement frequency is 100,1k and 10kHz. Exciting coil waa designed to measure the characteristics at maximum magnetic flux density 1.4T in 100Hz. The samples are Si-Fe steel, SK steel and SPCD (Steel Plate Cold Deep, down).The summarise of this study is as follows ;・It is possible that detect of crack at surface of magnetic materials. It is necessary that the crack laid to be perpendicular.・Change of the magnetic characterisitics according to the fatigue. But it is not clear between the fatigue and the magnetic characteristics.