Magnetic NDE technique for an estimation of degradation distribution in tensile-tested structural steel has been developed. In order to scan magnetic properties of steel promptly , magnetic yoke-probe having primary and secondary coils wounded around the yoke was adopted. To simplify the detection procedure, the principle same as the transformer was emplo yed. The voltage induced at secondary coil decreases with the increase in the applied tensile stress. As for spatial distribution of output voltage, the ...
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NDE of degradation distribution in tensile-tested specimen using magnetic sensing

小林 悟 Satoru KOBAYASHI Magnetic NDE technique for installed structural steels using a magnetic single-yoke probe has been leveloped. In order to apply this technique to practical use, it is important to clear influence of a contact gap netween a single-yoke probe and specimens . Here, we investigated magnetic properties measured by a ingle-yoke probe, when an air gap length between the probe and specim ens changes. BH loops incline to he axis of magnetic field and magnetic field at B =0 decreases with inc...
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Influence of contact gap on NDE using magnetic single-yoke probe

NDE techniques using magnetic methods such as hysteresis loop, Barkhausen noise, magnetoacoustic emission, permeability changes are used for characterization of ferromagnetic steels and eva luation of degradation of steels. Also, magnetic flux leakage testing is used for wall thinning on the tubes in various plants. In this paper, a feasibility of those magnetic techniques for applying evaluation of small defects with sub-mm size was examined. As the results, the techniques except MFL method have no abilit...
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NDE for defects with sub-mm size using magnetic techniques

Abstract Magnetic NDE of ferromagnetic steel using spectrum analysis of induced voltage at pick-up coil and magnetic induction has been studied. Magnetic yoke, having an excitation coil and a pick-up coil, was located on a specimen, and a sinusoidal current was applied to the excitation coil for magnetizing the specimen. A voltage induced at the pick-up coil was measured, and the corresponding magnetic in duction was calculated. Then, their frequency spectrums were obtained thorough Fourier analysis. For ...
英字タイトル:
NDE of ferromagnetic steel using spectrum analysis of changes in inducedvoltage and magnetic flux density