Magnetic compression effect in present MFL testing sensor

On the basis of the analysis of present MFL (magnetic flux leakage) testing sensors, the existence of MCE (magnetic compression effect) in present MFL testing sensors was specially pointed out and its relevant MCE theory was also analyzed, which manifest themselves in the compression of MFL in its volume caused by the background magnetic fields which have been overlooked. Afterwards, the presence of the proposed MCE was verified by simulations and experiments, which further indicates that the stronger background magnetic field is and the less MFL of defects forms. Furthermore, the MFL mechanism for MFL testing sensors were further discussed combining with MCE. The find of MCE and its relevant avoidance can increase the MFL in its volume, resulting in a new MFL testing sensor with a good sensitivity and a long distance and non-contact inspection method. Additionally, the work is of significant importance to the theory of MFL testing sensors by clearing and richening the MFL mechanism.