LAUSR

The traditional magnetic flux leakage (MFL) method with a single magnetic excitation source has been widely used in engineering practice but fails in long-range (long liftoff distance of the sensor from the surface of the tested object) defect detection, especially when the liftoff distances increase. Thus, we propose a novel electromagnetic testing method based on the magnetic field interaction between the primary magnetic induction field and the secondary field of MFL. The principles of the new method are first introduced, and the method is compared with the common MFL methods; this comparison indicates that the new method has the capabilities of long-range defect detection and signal strength enhancement. Furthermore, a series of simulations and analyses demonstrates that the proposed method is more efficient in defect detection, particularly when the induction magnet is a diamagnetic material, which is independent of the coercive force. Finally, experiments and comparisons were conducted to verify the feasibility and reliability of our proposed method in the long-range defect detection. All results show that the novel method has great promise in widely practical applications in the future.