A New Omni-Directional EMAT Using Contra-flexure Coils for Plate Inspection

Ultrasonic guided wave testing method, especially Lamb wave, is perfectly effective in nondestructive testing of complex structures like plate. Lamb wave excited by Lorentz force has the advantage of large detection range. However, the traditional transducer is difficult to identify the ultrasonic signal accurately because of its bidirectional propagation from one coil. To address this problem, a novel omnidirectional electromagnetic acoustic transducer (EMAT) with two contra-flexure coils (CFCs) is designed to achieve omnidirectional one-way propagation. At the same time, the ultrasonic signals are enhanced, which improve the signal to noise ratio. Through modeling and simulation, it is proved that the new transducer is more effective in omnidirectional energy transmission than the traditional one.