Reduction of lift-off effect for pulsed eddy current NDT based on sensor design and frequency spectrum analysis

Pulsed eddy current (PEC) nondestructive testing (NDT), as for most of EC techniques, is prone to lift-off effect, which influences the interpretation and quantification of flaw. A new technique for reducing the lift-off effect and quantifying flaw based on sensor design and frequency spectrum analysis is proposed. The technique exploits the self-differential feature of the sensor and the broadband frequency spectral content of pulsed excitation. Results show that the lift-off has been significantly reduced and the precision of quantification of flaw has been improved.