电磁超声加载方式对Lamb波模态的影响

Lamb waves are widely used in the field of nondestructive testing with the advantage of better directivity, higher detection efficiency and longer propagation distance etc. But there are always two or more modes existing at any frequency when Lamb waves are generated, and the propagation velocity of each mode is different, which makes the received echoes very complex, so the defect is difficult to be distinguished by analyzing the defect echoes. In this paper, based on multimode characteristics of lamb waves, the influence of electromagnetic acoustic excitation way on the lamb wave mode is researched, and lamb wave-mode control is achieved by choosing the loading way of electromagnetic acoustic transducer (EMAT), which improves excitation efficiency of corresponding Lamb wave-mode and restrains other modes, thereby reducing the difficulty of the subsequent signal processing, and providing useful information for identifying and locating defects in actual detection.