Design and Analysis of Meander Coil Electromagnetic Acoustic Transducer (EMAT) for Multi-mode Lamb Waves in Thin Plate

The generation and detection of multi-mode Lamb or plate waves in thin aluminum plate materials using Meander coil electromagnetic acoustic transducers (EMAT) is presented in this paper. EMAT works under the Lorentz force principle in non-magnetic materials. The generation of lower order or fundamental Lamb waves (S0 and A0) has been performed in both finite element (FE) simulations and experimental measurements. This paper is divided into three parts; first 2-D electromagnetic simulation model has been created for the Lorentz force calculation which is coupled by the induced or eddy current inside the material and the applied static magnetic field. The Lorentz force causes the vibration of sound waves inside the aluminum material. Second, the calculated Lorentz force densities are utilized as input sources for the generation of transient ultrasonic waves within the aluminum material. Third, the multimode Lamb waves (S0 and A0) have been excited with two different coil spacing EMATs an