Extension of a model for eddy current inspection of cracks to pulsed excitations

Calculations are carried out to evaluate pulsed eddy-current interaction with a crack in a planar conductor. The field is excited by a coil carrying current pulses and crack signals are detected by measuring changes in the magnetic field above the conductor. The model is based on the Fourier superposition concept, where the current pulses are decomposed into distinct frequencies. An existing boundary element method model for eddy current inspection of narrow cracks is used for each frequency and the final transient crack signal is synthesized by the individual frequency responses. The model is verified by a 3D finite element commercial package with a time-stepping technique. Computation times for the presented approach are orders of magnitudes shorter and allow rapid parametric studies of the transient signals for identification of principal component characteristics as well as for inversion purposes.