Examination of Plural Cracks Inspection Technique using Parallel Component of Alternating Leakage Flux

--Evaluation of 3-D Non-Linear Eddy Current Analysis and Experiment--

Abstract

The alternating magnetic flux leakage testing has been applied in the inspection process for detecting cracks on the surface of steel. Generally, the perpendicular (Bz) component of leakage flux is detected in this testing. Because, this component is not generated when there is no crack. However, when plural cracks are located at very short distance (L), the distinction of the numbers of cracks cannot be performed by using Bz component. In this paper, a technique of how to detect plural cracks that are located at very short distance is investigated using the parallel (Bx) component of leakage flux density calculated by 3-D edge-based hexahedral FEM. In addition, the experimental verification is also carried out.