Analytical modelling and calculation of pulsed magnetic field and input impedance for EMATs with planar spiral coils

Hao, Kuan-sheng; Huang, Songling; Zhao, Wei; Wang, Shen; Dong, Jing

doi:10.1016/j.ndteint.2011.01.001

Cited by 21 publications

(7 citation statements)

References 16 publications

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“…The frequency of the dynamic Lorenz force excited by the dynamic magnetic field generated by the alternating coil is two times that of the static Lorenz force, so the weak dynamic magnetic field can be omitted [17,18].…”

Section: Electromagnetic Modelmentioning

confidence: 99%

Numerical evaluation of focal position selection by line-focusing electromagnetic acoustic transducer with experimental validation

Huang

Sun

Wang

et al. 2019

International Journal of Applied Electromagnetics and Mechanics

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2019) 'Numerical evaluation of focal position selection by line-focusing electromagnetic acoustic transducer with experimental validation.', International journal of applied electromagnetics and mechanics., 61 (3). pp. 341-355.Abstract-As the focal position of a line-focusing electromagnetic acoustic transducer (LF-EMAT) affects the intensity of the focal signal, we measure the displacement signal and the slection method of the focal line position is then studied in this work to improve the signal intensity and detection precision for a shear-vertical (SV) wave LF-EMAT. We calculate the magnetostatics filed and bulk wave propagation utilizing the finite element method (FEM). We simulate the characteristics of the SV wave, and we find that the radiant distance and propagation direction has a great influence on the amplitude of the displacement of the specimen. The superposition area of SV waves from different sources possesses better focusing ability, and the triangular area (normalized amplitude of the SV waves lower than 10%) near the surface of a specimen should be avoided to be chosen when designing the meander line coils. As for the line-focusing EMAT described in this manuscript, the selection of focal positions for different thickness specimens or detection depth is completely different. Moreover, we perform an experiment to validate the simulation results and lead to a conclusion that the position of the focal point is required to be appropriately close to the excitation coils to enhance the intensity of the signal, while the best focal position should be calculated.

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Section: Electromagnetic Modelmentioning

confidence: 99%

Numerical evaluation of focal position selection by line-focusing electromagnetic acoustic transducer with experimental validation

Huang

Sun

Wang

et al. 2019

International Journal of Applied Electromagnetics and Mechanics

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“…Similarly, the back-plate is replaced by SiFe, Mn-Zn ferrite and low carbon steel respectively in the actual experiments. The intensity of ultrasonic wave generated by the EMAT becomes larger with the boost of the amplitude of the current in the coil [19], whilst the excitation current depends on the impedance matching between the coil and the power source [20,21]. The magnetic reluctance around the coil is reduced due to the magnetic back-plate, which leads to an increment of the coil's inductance.…”

Section: Experiments Validationmentioning

confidence: 99%

Enhancement of EMAT’s efficiency by using silicon steel laminations back-plate

Ren

Dixon

et al. 2018

Sensors and Actuators A: Physical

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“…To lower the calculation difficulty, the approximate series expression of eddy current are proposed by Truncated Domain Eigen-function Expansion method (TREE) [13][14][15]. where b represents the radius of the tested sample shown in Fig.…”

Section: Induced Eddy Current Densitymentioning

confidence: 99%

Analytical solution for the effect of the permittivity of coating layer on eddy current generated in an aluminum sample by EMAT

Sun¹,

Sun²,

Chen³

2016

AIP Conference Proceedings

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Abstract. In order to improve the ultrasonic wave amplitude excited by electromagnetic acoustic transducers (EMATs), many researchers have proposed models. But they always ignored displacement current or the effect of the permittivity of the air or the metal sample during modeling, due to its low permittivity. However, more durable dielectric materials are replacing or coating with metals in many applications which have a much higher permittivity than air or metal sample so that the effect of permittivity cannot be ignored. Based on an analytical model, the effect of the permittivity of coating layer on the eddy current generated in an aluminum sample by EMAT has been studied. The analytical analysis indicates that the eddy current density excited by the spiral coil of EMAT slowly increases in the beginning and then decreases rapidly while the permittivity increases, and it has much relation to the thickness of the coating layer and the exciting frequency, which is verified by the simulation result.

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Analytical modelling and calculation of pulsed magnetic field and input impedance for EMATs with planar spiral coils

Cited by 21 publications

References 16 publications

Numerical evaluation of focal position selection by line-focusing electromagnetic acoustic transducer with experimental validation

Numerical evaluation of focal position selection by line-focusing electromagnetic acoustic transducer with experimental validation

Enhancement of EMAT’s efficiency by using silicon steel laminations back-plate

Analytical solution for the effect of the permittivity of coating layer on eddy current generated in an aluminum sample by EMAT

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