Identifying Surface Defect Opening Profiles Based on the Uniform Magnetic Field Distortion.

Accurate identification of the defect opening profile is significant to quantify the size of defects for the ferromagnetic components. However, traditional non-destructive testing methods are difficult to obtain the image of defect opening contours precisely, especially the complex opening shapes. To solve the problem, we developed a novel opening profile identification method based on the distortion of the uniform magnetic field (UMF). This method has the same detection sensitivity to the defect edge in any direction, and accurate imaging of the defect opening profile can be achieved using the vertical component of the UMF distortion signal merely. In order to examine the feasibility and accuracy of the proposed method, regular and irregular defect models are simulated. In addition, an experiment for an artificial defect is conducted. All results show that the novel method has great promise in practical application.