Crack opening shape reconstruction method in magnetic flux leakage imaging

Magnetic flux leakage (MFL) is widely used in the detection of ferromagnetic materials. In the study of the reconstruction of cracks, the opening crack shape reconstruction method is the first and crucial step. However, current research concerns little about the reconstruction of the opening profile. This paper proposed an opening shape reconstruction method by introducing the Newton-Raphson and iterative Tikhonov regularization method. And the solenoid model applicable to the derivation of magnetic fields with complex defects is presented as an analytical forward model of magnetic fields. The sensitivity matrix of the analytical model of the magnetic field is adapted by improving the differential method of the magnetic field. The comparative experimental results show that this method has good results for defect profile reconstruction in MFL inspection and has apparent advantages in accuracy compared with the traditional defect profile segmentation method.