Transformation of the rotating eddy current testing signal at the desired eddy current orientation

Abstract

The results of rotating eddy current testing can be regarded as the results superposed by uniform eddy current testing in orthogonal directions. However, in the case of directional nondestructive testing problems, such as weld detection, only the results from the induced current that is perpendicular to the crack have the greatest sensitivity. In contrast, the results from other induced current orientations may experience substantial noise generated by welds. In this work, a brief method is proposed to transform the results of rotating eddy current testing into the results of uniform eddy current testing at the desired eddy current orientation. The experiments indicated a good match between the signal distribution and amplitude of the transformed results and the results of the uniform eddy current testing. Moreover, the proposed method was applied for weld detection. The results revealed that the weld noise significantly decreased and that the locations of slits could be clearly identified. The results validated that the proposed method can improve the detection ability and expand the application of the rotating eddy current testing technique.