Analysis of Pulsed Eddy Current Signals Using Time-Frequency Method

摘要

Detection and measurement of the material loss due to corrosion in aircraft fuselage lap splices are of great importance to life management of ageing aircraft. Pulsed eddy current (PEC) techniques have shown the potential to characterise these structures. However, variations in the probe lift-off, the interlayer gaps and material thinning produce similar response, making signal interpretation very difficult. In this paper, time-frequency analysis methods are applied to pulsed eddy current signals with the objective of discriminating between the simultaneous occurrence of material loss and changes due to lift-off or interlayer gap. This study shows that the time-frequency analysis of PEC signals provides specific visual patterns that can be related to the interlayer gap, lift-off, and material loss.