Effects of excitation system on the performance of magnetic-flux-leakage-type non-destructive testing

The effects of excitation system on the performance of magnetic flux leakage (MFL)-type non-destructive testing were investigated. The investigation employed parameterized finite element analysis of the MFL testing of ferromagnetic samples to reveal the effects of the structural design and parameters of the excitation system, including the geometry and dimensions of the yoke, lengths and positions of coils and thickness of the shielding layer. Moreover, a parameter optimization method, combining parameterized finite element analysis with a genetic algorithm, was proposed to optimize the dimensions of the yoke and thus obtain maximum magnetic flux leakage. Simulation and optimization results were used to propose an MFL sensor with a preferred structural design and preferred parameters of the excitation system. Comparative experiments were conducted to validate the numerical simulation results. The experimental results agreed well with the results of numerical simulation, and the superior performance of the MFL sensor with the preferred excitation system was validated.