Yuedong Xie

Simulation of an Electromagnetic Acoustic Transducer Array by Using Analytical Method and FDTD

Previously, we developed a method based on FEM and FDTD for the study of an Electromagnetic Acoustic Transducer Array (EMAT). This paper presents a new analytical solution to the eddy current problem for the meander coil used in an EMAT, which is adapted from the classic Deeds and Dodd solution originally intended for circular coils. The analytical solution resulting from this novel adaptation exploits the large radius extrapolation and shows several advantages over the finite element method (FEM), especially in the higher frequency regime. The calculated Lorentz force density from the analytical EM solver is then coupled to the ultrasonic simulations, which exploit the finite-difference time-domain (FDTD) method to describe the propagation of ultrasound waves, in particular for Rayleigh waves. Radiation pattern obtained with Hilbert transform on time-domain waveforms is proposed to characterise the sensor in terms of its beam directivity and field distribution along the steering angle, which can produce performance parameters for an EMAT array, facilitating the optimum design of such sensors.

Directivity analysis of meander-line-coil EMATs with a wholly analytical method.

HIGHLIGHTSWe propose a wholly analytical model for meander‐line‐coil EMATs.The Dodd and Deeds solution adapted for the straight wire.Radiation pattern of Rayleigh waves obtained with the proposed model.Wire lengths effect on the directivity of Rayleigh waves analysed quantitatively. ABSTRACT This paper presents the simulation and experimental study of the radiation pattern of a meander‐line‐coil EMAT. A wholly analytical method, which involves the coupling of two models: an analytical EM model and an analytical UT model, has been developed to build EMAT models and analyse the Rayleigh waves’ beam directivity. For a specific sensor configuration, Lorentz forces are calculated using the EM analytical method, which is adapted from the classic Deeds and Dodd solution. The calculated Lorentz force density are imported to an analytical ultrasonic model as driven point sources, which produce the Rayleigh waves within a layered medium. The effect of the length of the meander‐line‐coil on the Rayleigh waves’ beam directivity is analysed quantitatively and verified experimentally.

A Wholly Analytical Method for the Simulation of an Electromagnetic Acoustic Transducer Array

This paper presents a wholly analytical method which combines electromagnetic and ultrasonic simulations for the study of an Electromagnetic Acoustic Transducer Array (EMAT). Analytical solutions to the eddy current problem for the meander coil used in an EMAT are adapted from the classic Deeds and Dodd solution, which was originally intended for circular coils. The analytical solution resulting from this novel adaptation exploits the large radius extrapolation and shows several advantages over the finite element method (FEM), especially in the higher frequency regime. The calculated Lorentz force density from the EM solver is then coupled to the ultrasonic simulations, which exploit an analytical solution for generating the distribution of surface waves. Beam features are studied, which can produce performance parameters for an EMAT array, facilitating the optimum design of such sensors. This total analytical approach to an EMAT simulation has not been reported previously to our knowledge.

Simulation and experimental verification of a meander-line-coil electromagnetic acoustic transducers (EMATs)

This paper presents a method combing analytical and finite-difference time-domain (FDTD) methods to build meander-line-coil EMATs. Lorentz force densities are calculated using analytical solutions adapted from classic Deeds and Dodd solution, which then are imported to ultrasonic simulations. The propagation of ultrasound waves is numerically simulated using finite-difference time-domain (FDTD) method to describe their propagation within homogenous medium and their scattering phenomenon by cracks. Experiments are set up to verify the proposed method.

Measurement of liquid level with a small surface area using high frequency electromagnetic sensing technique

Liquid level measurement is an important requirement in many industrial applications. Several measurement approaches have been studied previously, including inductance methods suitable for an infinite surface area. In this paper, we presented a novel approach based on the high frequency electromagnetic induction technique for the measurement of liquid level with a small surface area. In this situation, the analytical approach we developed previously is no long valid. Sensitivity analysis was carried out and the optimal coil configuration of the sensor proposed. Experiment results have confirmed the validity and effectiveness of our proposed approach based the electromagnetic sensing principle.