Analysis of excitation current parameters in pulsed eddy current testing for ferromagnetic metallic materials

In pulsed eddy current (PEC) testing, excitation signal parameters are of great importance for the probe detectability. Square-wave current excitation with linear ramp edges used in measuring steel-plate thickness is studied in this work. Based on spectrum analysis, simulation and experimental study, the influences of the duty cycle and edge transition time on response signals are analyzed. Results show that for thin specimens the duty cycle can be decreased properly but the edge time should be as small as possible, and for thick specimens the duty cycle should be close to 50% while the edge time can be increased properly. This study can provide a reference for PEC signal interpretation and optimization of excitation parameters.