An Advanced Magnetoacoustic Compound Inspection Method of High-Order Mode EMAT

Abstract

In this study, an advanced magnetoacoustic compound inspection method for a high-order Lamb waves mode electromagnetic acoustic transducer (EMAT) was proposed. The proposed EMAT can achieve the excitation and reception of the A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode which is the first-order Lamb waves mode. According to the characteristics of the A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode EMAT testing signal, a signal processing method for obtaining the pulsed eddy current signal by curve fitting was developed to extract the information for the pulsed eddy current. The voltage of the ultrasonic waves was carried on the pulsed eddy current voltage, and it was obtained by removing the pulsed eddy current voltage and extracting the time-domain testing signal of the A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode EMAT. Through A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode EMAT single detection that was used to obtain the pulsed eddy current and A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode, the multi-parameter from the magnetoacoustic compound testing signal of the A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode EMAT could be used to characterize the aluminum plate performance degradation. The detection accuracy of aluminum plate performance degradation was improved by the magnetoacoustic compound inspection compared with a single detection method.