3-D modeling and analysis of meander-line-coil surface wave EMATs

Surface wave electromagnetic acoustic transducers (EMATs) are becoming preferred sensors of automatic inspection systems for the detection of surface-layer defects in hostile environments. Aiming at establishing a 3-D model for meander-line-coil surface wave EMATs operating on the Lorentz principle, a novel modeling method is proposed by combining numerical calculations and analytical solutions with special attention to the influence of the dynamic magnetic field. Simulation and analysis find that the frequency of the surface waves due to the dynamic magnetic field is twice that due to the static magnetic field; the excitation of surface waves with two frequencies can effectively improve the sensitivity of EMATs to flaws; and the force due to the dynamic magnetic field generates surface waves more efficiently than that due to the static one when the excitation current exceeds 528.9 A. The accuracy of the established model is verified by experiment.