导电平板中的远场涡流特性

Characteristic of Remote Field Eddy Current in Metallic Plates

远场涡流现象一直被认为仅在管道中才存在，而远场涡流效应的远场涡流检测技术的最大特点在于它能以同样的灵敏度检测管内、外壁缺损，不受集肤效应的限制。在管道远场涡流检测机理研究的基础上，本文运用有限元法对导电板材中的远场涡流现象的产生及其特性进行了数值仿真研究，提出了采用磁路和磁电组合屏蔽控制与导引能量流的扩散实现了在导电平板中产生远场涡流效应，阐明了其形成机理并研究工作频率、平板厚度及气隙等参数变化对导电平板中远场涡流现象的影响，将之与管道中的远场涡流现象规律进行了比较，为导电板材的远场涡流检测技术奠定了基础。

It has been considered that the remote field eddy current (RFEC) phenomenon can be observed only in the conducting tubes. The main characteristic of the RFEC inspection technique based on RFEC effect is that it gains the same sensitivity to detect the inner and the outer defect of the tube wall without the limitation of the skineffect. Based on the study of RFEC inspection principle, the occurrence and characteristics of the RFEC phenomenon in metallic plates have been studied by finit element simulation. The RFEC effect can occur in metallic plates by using magnetic circuit and electromagnetic shield to control and guide the diffusion of electromagnetic energy flow, and the form principle has been clarified. Changing of parameters such as frequency, thickness of metallic plates and gap can influence the RFEC phenomenon in metallic plates, and it has been compared with that in the tube. The foundation for fulfilling the RFEC technique for metallic paltes is established.