脉冲远场涡流检测中磁场抑制技术

脉冲远场涡流用于飞机机身金属结构中缺陷的检测时,由于信号微弱,检测灵敏度往往不高,因此,如何实现对远场涡流的磁场抑制与信号增强,从而改进和提高其检测能力是一个关键问题。从抑制远场涡流磁场直接耦合分量的角度出发,仿真设计了带有不同屏蔽结构的传感器模型,分析了不同材料的屏蔽效果,比较了不同模型的缺陷检测灵敏度以及对大厚度平板的检测能力。研究结果表明:基于高导磁材料屏蔽盘的连通磁路传感器对直接耦合分量具有较好的抑制作用,可以拉近激励与检测线圈间的距离,提高缺陷的检测灵敏度,其对非磁性平板的检测厚度可扩展至25mm。

Research on Magnetic Field Suppression Technique in Detecting Pulsed Remote Filed Eddy Current

Aimed at the problems that the signals of traditional remote field eddy current are weak, and the detection sensitivity is low, and how to realize the suppression of the magnetic field in the remote field eddy current is a key problem to improve the detection ability, this paper designs some sensors with different shield structure from the perspective of restraining direct coupling component of magnetic field, analyzes the effect of shield with different materials, and compares the defects, detection sensitivity and the capability of detecting large thick flat geometry. The results show that the sensor with the connected magnetic circuit based on high magnetic shield has a good ability in restraining as for the direct coupling component, and can shorten transient length, can narrow the distances between the excitation and the detection coil, and can improve the sensitivity in detecting defects. And its detection depth can be extended to 25mm as for nonmagnetic plate.