直流磁場計測による分岐き裂の非破壊評価

概要

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Nondestructive evaluation of bifurcated cracks is a key issue in maintenance of tracks for high-speed trains. Magnetic flux density for a rectangular parallelepiped material in which direct current flows is analyzed. The material contains an embedded and through-wall horizontal crack and a bifurcated crack from the horizontal one. The magnetic flux density in the air near the top surface of the rectangular specimen is obtained by using a 3-D finite-element method. The maximum change due to the cracks in the component of magnetic flux density in the direction of the width of the rectangular parallelepiped is shown to be related to the length and the depth of the horizontal crack and the bifurcated crack. A technique of quantitative nondestructive evaluation of the vertical component of the bifurcated crack is proposed and is verified by experiment.
1995-11-25