A Spatial Broadband Magnetic Flux Leakage Method for Trans-scale Defect Detection

As an efficient non-destructive testing (NDT) method, the magnetic flux leakage (MFL) method has been widely used to evaluate various ferromagnetic materials over the years. Recently, by using magnetic heads, MFL has been utilized for identifying micro-cracks with the advantage of high sensitivity. However, traditional magnetic heads cannot be used to detect trans-scale defects because a single-gap-based probe has a limited detection range. To expand the probe's detection range, this work proposes a spatial broadband MFL sensing method by using a multiple-gap-based probe. Both the simulation and experimental results show that compared with single-gap-based MFL, the proposed method achieves better performances in the detection of trans-scale defects, which obtains the highest total gain of 92.78.