Journal of The Japanese Society for Non-Destructive Inspection
Print ISSN : 0367-5866
Volume 55, Issue 10
Displaying 1-2 of 2 articles from this issue
  • Noritaka YUSA, Ladislav JANOUSEK, Kenzo MIYA
    2006 Volume 55 Issue 10 Pages 531-535
    Published: 2006
    Released on J-STAGE: November 22, 2006
    JOURNAL FREE ACCESS
    This paper experimentally demonstrates that controlling AC distribution inside conductive material enables one to perform volumetric examination using electromagnetic phenomena. Several current distributions are superposed to locally realize AC distribution having a phase difference of 180 degrees between currents flowing near the surface and those deeply inside, and having non-exponential decay in depth direction. Experimental results clearly show that measuring the phase of magnetic field outside the material as a function of the ratio of the superposition provides information about the depth of defects quantitatively. In addition, this approach is applicable even though the depth of defects is much deeper than the standard depth of penetration; experimental results show clear differences between signals due to near-side notches 10, 12, 15, and 20 mm deep, when an exciting frequency of 100 kHz is adopted.
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  • Shoichi IIMURA, Yoshiaki SAKAI
    2006 Volume 55 Issue 10 Pages 536-542
    Published: 2006
    Released on J-STAGE: November 22, 2006
    JOURNAL FREE ACCESS
    A method is developed to nondestructively estimate stresses in bent pipes by magnetic anisotropy sensor. The values measured by the magnetic method contain both stresses generated during manufacture and generated by external forces. In-plane-bending tests of a welded elbow and an induction pipe bend were performed. The stresses obtained by the magnetic method were regressed to Karman's theoretical equation for a bent pipe. From the regression curve obtained, it was possible to obtain the external moment that was purely applied to the bent pipe. The stress range where measurement is possible is lower than that in a straight pipe, because the residual stress is even larger than that of a straight pipe.
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