Proposal of Detecting Method of Plural Cracks and Their Depth by Alternating Flux Leakage Testing - 3-D Nonlinear Eddy Current Analysis and Experiment -

摘要

The alternating magnetic flux leakage testing is used for the detection of cracks on the surface of steel plate. In this paper, a new technique of how to detect plural cracks and their depth, which are located at very short distance each other, is proposed. The leakage flux density of the parallel (x-) component is used for the distinction of the plural cracks. Moreover, the depth of plural cracks is obtained by changing the exciting frequency and by detecting the perpendicular (z-) component of leakage flux. The behavior of leakage flux is examined using 3-D edge-based hexahedral FEM and compared with experiment.