Abstract
The purpose of this study is to characterize the features of magnetic flux density perturbation as a result of the variation of conductivity in an equivalent model of the stress-corrosion crack (SCC). By using numerical computation of A-𝜙 method, the magnetic field nearby the inspection target was simulated for an eddy current probe of large rectangular excitation coil and a conductor plate with a modeled SCC. A conductive notch was set in the center of the conductor plate as an equivalent crack model of a real SCC. Different conductivities and crack depths were varied into the equivalent SCC model for analyzing their influences to the distribution of magnetic flux density perturbation above the model plate. Numerical results showed that the distributions of magnetic flux density were suitable to distinguish the difference of the conductivities of the SCC between 0% and 20% of the base material for normal testing frequencies. In addition, it was also found that the profile of distributed conductivity along the crack length can be better represented with the field induced by the excitation current laterally to the crack length.
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