Coil parameter analysis of meander-line coil electromagnetic acoustic transducer-based Rayleigh waves

摘要

A three-dimensional model for Rayleigh wave electromagnetic acoustic transducers operating on the Lorentz force mechanism has been established by combining the finite element method and analytical calculation. Rayleigh waves generated by the Lorentz forces due to the static magnetic field and the dynamic magnetic field are calculated. The ratio of wire width to spacing interval (RWWSI) between neighbouring wires is chosen to study the coil parameter influence of Lorentz forces in generating Rayleigh waves. The vibration amplitude of Rayleigh waves due to the dynamic magnetic field is almost proportional to the reciprocal of the RWWSI, whereas that due to the static magnetic field decreases slowly with the increase of the RWWSI. The divergence angles of Rayleigh waves due to the dynamic magnetic field remain invariable when the RWWSI is less than 0.5, and that due to static magnetic field reaches the minimum values and has better detectability when the RWWSI is 0.5. The critical excitation current, at which Rayleigh waves due to static and dynamic magnetic fields are equal, changes sharply when the RWWSI differs. The accuracy of this method is verified by experiment.