The wall-thinning measurement of ferromagnetic plates covered with insulations and claddings is a main challenge in petrochemical and power generation industries. Pulsed eddy current testing (PECT) is considered as a promising method. However, the accuracy is limited due to the interference factors such as lift-off and cladding. In this study, by decoupling analytic solution, a feature only sensitive to plate thickness is proposed. Based on the electromagnetic waves reflection and transmission theory, cladding-induced interference is firstly decoupled from the analytical model. Moreover, by using the first integral mean value theorem, interferences of insulation and the lift-off are decoupled, too. Hence, the method is proposed by calculating Euclidean distances between the normalized detection signal and normalized reference signal as the feature to assess wall thinning. Its effectiveness under various conditions is examined and results show that the proposed feature is only sensitive to the ferromagnetic plate thickness. Finally, the experiment is carried on to verify this method practicable.

中文翻译：

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解析涡流解耦法评估铁磁板的脉冲涡流薄壁化

覆盖有绝缘层和覆层的铁磁板的壁厚测量是石化和发电行业的主要挑战。脉冲涡流测试（PECT）被认为是一种很有前途的方法。然而，由于诸如剥离和包层的干扰因素，精度受到限制。在这项研究中，通过将解析解耦，提出了仅对板厚度敏感的特征。基于电磁波的反射和传输理论，首先将包层引起的干扰与解析模型解耦。此外，通过使用第一积分平均值定理，绝缘和剥离的干扰也被解耦。因此，该方法是通过计算归一化检测信号和归一化参考信号之间的欧几里得距离作为评估壁变薄的特征而提出的。检查了其在各种条件下的有效性，结果表明所提出的特征仅对铁磁板的厚度敏感。最后，通过实验验证了该方法的可行性。