Modeling of current excitation waveforms for magnetic particle inspection

In magnetic particle inspection, the sample is magnetized using current flow (coils) or flux flow (yoke). In both cases the excitation current may be alternating, full wave rectified, half wave rectified or pulsed. Further, these current waveforms vary significantly with current settings and time with no correlation between peak height and root mean square (nns) value. The choice of inappropriate electrical current waveforms can potentially result in missing some significant defects. This paper presents a finite element modeling study of the magnetization of a test sample due to different current waveforms. The model uses time samples of the waveform and generates magnetic flux density variations at any arbitrary point in the solution domain due to different excitation currents and peak, values. The results and effects of current waveforms are presented and discussed.