コンクリートにおけるクラック深さの磁気的非破壊計測  [in Japanese] Nondestructive Magnetic Measurement of the Depths of Cracks in Concrete  [in Japanese]

This paper presents a method for estimating the depth and inclination angle of a crack in concrete. Amorphous magnetic powders were packed into a crack and magnetized with an E-form ferrite core with a pick-up coil centered between the two exciting coils. To model the crack, acrylic parallelograms of various lengths and widths were prepared and packed with amorphous magnetic powders. The magnitude and phase of the magnetic flux caused by the crack packed with amorphous magnetic powders were measured. The experimental results show that the inclination angle could be clearly recognized, and the depth of the crack was determined to be 30mm. The magnetic flux through the pick-up coil was analyzed by the Integration Element Method. The calculated values of the magnetic flux agreed approximately with the measured values.