Analytical model for probe impedance using reflection and transmission theory in eddy current testing
基于反射与折射理论的电涡流检测探头阻抗解析模型

The analytical model of probe impedance due to multilayered conductive structures is established using the reflection and transmission theory of electromagnetic waves in eddy current testing. The electromagnetic field in the region under considecation consists of the excitation field of the coil and the eddy current field. The eddy current field is regarded as the combination of the reflection and transmission of the excitation field. Therefore, the probe impedance is analytically modeled by applying the series-form representation of the excitation field and the reflection and transmission theory of electromagnetic waves, thus resulting in a series-form expression. Finally, the calculated results from the typical integral-form and developed series-form expressions were compared, and experiments were carried out. The good agreement between the calculated and experimental results justifies the presented analytical model. In comparison with the infinite integral of probe impedance, the series-form expansion has advantages of not needing the determination of the integral upper limit, saving time and easy control of the error.