Coupled finite element model for the pulse-echo behavior of electromagnetic acoustic transducers

Electromagnetic acoustic transducers (EMATs) are widely used for nondestructive testing of electric conductive materials. The practical application of EMATs is limited by their low transduction efficiency. A 2-D finite element model to study the pulse-echo behavior of meander coil EMATs operating on the Lorentz force principle, is presented in this paper. The 2-D model is a multi-field coupled model, which involves the electromagnetic field and the mechanical field. These two physical fields are coupled together by the Lorentz forces in the generation process and the elastic wave vibration velocities in the reception process. The same geometry is shared and the multi-physical phenomena are calculated simultaneously. The EMAT transmitting and receiving process can be described by this coupled model. Our numerical work is extended to analyze the influence of excitation frequency and wire width on the induced voltage. The simulation results agree well with the experimental measurements, verifying the validity of the presented method.