The Reduction Technology of Lift-off Effects for Pulsed Eddy Current Testing Based on Frequency Spectrum Analysis

It was prone to bring lift-off effects in pulsed eddy current testing(PECT) because of probe incline, which influenced badly to the precision of quantification of defects. Using the feature that the pulsed excitation has affluent frequency ingredients, a new technology for reducing the lift-off effects based on frequency spectrum analysis was proposed. Through the testing, it was found that the low-frequency part of the processed signal by the technology has been almost in agreement with the original testing signal with lift-off, the effects have been reduced and the depth of the defects can be measured through getting the low-frequency characteristic peaks. The results showed that significant reduction in the effects was achieved and the precision of quantification detection for defects was improved.