Theoretical analysis and simulation of an enhancement method for the micro-crack signal in MFL inspection

摘要

The micro-crack is always difficult to discover in the widely applied magnetic flux leakage (MFL) inspection because of the weak leakage magnetic field. Hence, a novel method for enhancing the micro-crack signal based on the magnetic particle adsorption is proposed. The mechanism of magnetic field distribution in the vicinity of the micro-crack based on the new method is analyzed from the angle of magnetic refraction. The confirmation for the signal enhancement and further discussion are presented with the finite element simulation. Simulation results indicate that the signal of the micro-crack is significantly enhanced based on the magnetic particle adsorption which confirms the feasibility of the novel method. In addition, the ability of the signal enhancement is more relevant to the maximum height than the maximum width of the magnetic particle indication, and the signal increases when the relative permeability of the gathered magnetic particles is bigger.