Pulsed eddy current array design and electromagnetic imaging for defects detection in metallic materials

Defects caused by a harsh working environment and cyclic loading may seriously lead to catastrophic industrial accidents. Therefore, an efficient and accurate detection method is needed to quantitatively characterise the multiple defects of large-area metal components. In this paper, a pulsed eddy current (PEC) array is designed by considering mutual electromagnetic influence between the PEC array; the differential peak values at different scan positions are abstracted as feature signals for defect characterisation, and the relationship between defect width and detection signal is discovered; the detection capability of sensor array for adjacent defects is analysed. Subsequently, the electromagnetic imaging is applied to visualise and quantitatively evaluate the multiple defects, and then, the quantitative detection approaches for the localisation and width of multiple defects in metal components are proposed. An experimental setup is built and the proposed approach is validated by experiment. The results show that the proposed method can effectively determine the locations and widths of defects in metal components within the absolute error of 1 scan step.