Affiliations: [a] State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha, Hunan, China | [b] School of Electrical and Mechanical Engineering, Central South University, Changsha, Hunan, China | [c] Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Changsha, Hunan, China
Correspondence:
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Corresponding author: Yunxin Wu, School of Electrical and Mechanical Engineering, Central South University, Changsha, Hunan 410083, China. Tel.: +86 731 8866 0476; E-mail:wuyunxin@csu.edu.cn
Abstract: Three differential equations based on different
definitions of current density are compared. Formulation I is based on an
incomplete equation for total current density (TCD). Formulations II and III
are based on incomplete and complete equations for source current density
(SCD), respectively. Using the weak form of Finite Element Method (FEM), the
three formulations were applied in a meander coil Electromagnetic Acoustic
Transducer (EMAT) example to solve magnetic vector potential (MVP). The FEM
results from frequency domain and time domain models are in excellent
agreement with previously published works. Results show that the errors for
Formulations I and II vary with coil dimensions, coil spacing, lift-off
distance and external excitation frequency, for the existence of
eddy-current and skin and proximity effects. And the current distribution
across the coil conductors also follows the same trend. It is better to
choose Formulation I instead of Formulation III to solve MVP when the coil
height or width are less than twice the skin depth, due to the low cost and
high efficiency of Formulation I.
Keywords: Electromagnetic acoustic transducer, eddy current, finite element method, skin and proximity effects
