A new MFL principle and method based on near-zero background magnetic field

摘要

On the basis of the analysis of the MCE (magnetic compression effect) in present MFL (magnetic flux leakage) applications, a new MFL principle and technique based on the establishment of a near-zero background magnetic field is proposed for the first time, resulting in an increase of MFL allowing a non-contact MFL signal pick-up at larger probe lift-off. Afterwards, the feasibility of the proposed principle is justified by simulations and experiments. Finally, their advantages are presented. By applying the proposed MFL principle, the severe wear of contact probes can be avoided and inspection at high-temperature heat pipes can be performed. The contributions of the technique to reduce magnetic noise, distortion and the saturation of hall sensors are also discussed.