A Composite Approach of Electromagnetic Acoustic Transducer and Eddy Current for Inner and Outer Corrosion Defects Detection

In the production and service of pipelines, automated electromagnetic detection is widely employed to diagnose potential defects. However, the single inspection method can hardly multiposition detect detection simultaneously due to limited signal features. In this article, a novel composite approach of electromagnetic acoustic transducer (EMAT) and eddy current (EC) is proposed to detect different kinds of defects by combining their technical merits. A comprehensive theoretical analysis of the composite approach is given to derive the modified model of the send-receive mode. The influences of the critical parameters on hybrid signals are discussed and the probe performance is improved by over 65% in magnitude. Then, the time-division multiplexing strategy is utilized to separate hybrid signals. Finally, laboratory experiments are conducted to extract independent features and diagnose potential defects in the steel plate. Results indicated that the proposed approach could achieve a good performance in the detection task of inner and outer defects. Compared with existing detection methods, our proposed approach has significant merits in detectability and efficiency.