A hybrid nondestructive testing method of pulsed eddy current testing and electromagnetic acoustic transducer techniques based on wavelet analysis

Abstract

It is found that the electromagnetic acoustic testing (EMAT) signal itself contains part of the pulsed eddy current testing (PECT) signal. Therefore, if the pulsed eddy current signal embedded in the electromagnetic ultrasound signal can be effectively extracted and used, the hybrid nondestructive testing method of electromagnetic ultrasound and pulsed eddy current can be truly realized. Based on the above concept, the authors have obtained some preliminary results through simple signal processing try, and which gave us a promising hope of this hybrid method. To further verify the validity and strengthen the usability of the hybrid method, more effective signal separation and extraction way to the hybrid detection signals is expected, which is the core step. In this study, a new signal separation and extraction method is proposed for the hybrid detection signals in the PECT/EMAT nondestructive testing method based on wavelet analysis strategy. The effectiveness and merits of the proposed signal separation method compared to the previous way is verified through the numerical simulation as well as experiment.