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| | Abstract | | The applicability and feasibility of eddy current detection method for the measurement of wall thinning and surface crack of steel structure have been practically confirmed by field and laboratory experiments. Recently, we could roughly understand whether or not there is a defect. However, it is difficult to estimate the exact position, size and shape of that. For more accurate inspections, there has been a growing demand to quantitatively evaluate the defects. Therefore, we have developed a numerical simulator to consider whether we could develop the high accuracy eddy-current method. Eddy current method uses the information of excitation and induced magnetic field of conducting material. In order to calculate the induced magnetic field by the defects, we used a 2.5 dimensional finite-difference frequency domain technique (2.5D-FDFD) to solve Maxwell's equations numerically. In this technique, we assumed the two-dimensional structure and the three-dimensional electromagnetic field. We used two-layer structure consisting of seawater and steel plate containing defects. To estimate characteristic of the induced magnetic field, we simulated for a variety of defects and compared what effect appear. As a result, we could confirm the effect of surface defects of steel plate on receiving magnetic field. |
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