境界要素法を用いた渦電流式膜厚計に関する電磁場解析

抄録

An electromagnetic field of an eddy current thickness sensor was analyzed for the purpose of improving measurement accuracy. Maxwell equations were discretized with the boundary element method. In order to facilitate the calculation, a quasi-stationary approximation and an axisymmetric one were employed. A numerical integration formula with high accuracy was applied to evaluate a singular integral. A special element was developed for effective analysis of a thin film. It is found from numerical results that the radial component of magnetic flux density produced by the eddy current is greater than the axial component in nickel-plated steel. Using this property, a new thickness sensor for a metal film on a metal substrate was realized.