Numerical simulation of magnetic incremental permeability for ferromagnetic material

Magnetic Incremental Permeability (MIP) method practiced as a NDT technique to evaluate the material degradation is based on the eddy current testing in addition to a low frequency bias magnetic field generated by an electromagnetic magnet. To clarify the mechanism of MIP and to find optimal probe design, a numerical method to simulate MIP profile is important. In this paper, a simulation scheme and a numerical code are developed for MIP of ferromagnetic material based on the simulated polarization strategy and the reduced vector potential formulae. Experiments are also conducted for test-pieces of carbon steel to demonstrate the validity of the proposed scheme.