Technology of Damage Imaging of the Steel Plate-like Structure Based on EMAT

The paper researches the damage imaging of the steel plate-like structure by using orthogonal matching pursuit based on tEP and the theory of time reverse.At first the electromagnetic acoustic transducer (EMAT) is used to excite and receive Lamb wave on the plate,the signal is processed with matching pursuit algorithm to improve signal quality;Then the algebraic difference is performed for the signals and a set of time reversal signal are obtained by combining with time reverse theory;Finally,damage imaging is realized in accordance with the principle of synthetic imaging.Experiments show that this method can extract the envelope signal precisely and accurately monitor the defect features.