Efficient computer modelling of interaction of field and surface crack in surface magnetic field measurement technique

A computer technique for an efficient analysis of surface electromagnetic field distributions induced by U-shaped current-carrying wires and rectangular coils around fatigue cracks in ferrous metals was presented. The technique employs the unfolding method in conjunction with a bipolar conformal mapping in order to reduce the problem to a 2-D Laplace equation subject to appropriate boundary conditions. This equation is solved using a fast Fourier transform. Computed results were presented and where possible, the accuracy of the technique was verified by measurement