An Analytical Model of a New T-cored Coil Used for Eddy Current Nondestructive Evaluation
关键词:
Analytical model, coil impedance, eddy current testing, non-destructive evaluation, T-core coil, truncated region eigenfunction expansion摘要
A model of an axisymmetric probe with a new T-core coil that can be used in eddy current testing is developed. The truncated region eigenfunction expansion (TREE) method is used to analyze the coil impedance problem of the T-core coil located above a multi-layer conductive material. First, the magnetic vector potential expressions of each region are formulated, then the coefficients of the magnetic vector potential are derived by using the boundary conditions, finally, the closed form expression of the coil impedance is obtained. The normalized impedance changes of the T-core coil caused by the presence or absence of the multi-layer conductor are calculated using Mathematica. The presented T-core coil is compared with I-core coil and air-core coil. The effects of the T-core parameter a2, relative permeability μf and the thickness of the top section on the change in the coil impedance are discussed respectively. The analytical calculation results are compared with the results of finite element method, and the two agree very well, which verifies the correctness of the proposed T-core coil model.
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参考
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