脉冲远场涡流检测中磁场抑制技术研究

通过传感器结构的合理设计,脉冲远场涡流可用于飞机机身非磁性金属结构中缺陷的检测,但是,传统远场涡流信号微弱,检测灵敏度不高,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。本文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,可以缩短过渡区,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 the Detection of Pulsed Remote Filed Eddy Current

Through reasonable design of sensor structure, pulsed remote field eddy current technique can be used in the detection of the defects in the nonmagnetic metal components of planes, but the signal of traditional remote field eddy current is weak, and the detection sensitivity is not enough, therefore, how to realize the suppression of the magnetic field in the remote field eddy current is a key problem to improve the detection ability. In this paper, sensors with different shield structure have been designed from the perspective of restraining direct coupling component of magnetic field, the effect of shield with different materials has been studied, meanwhile, the defects detection sensitivity and the capability of detecting large thick flat geometry has also been discussed. The results of simulation show that the sensor with connected magnetic circuit and high magnetic shield has a good ability in restraining the direct coupling component, and it also can shorten transient length, narrow the distance between the excitation and the detection coil, improve defects detection sensitivity. And its detection depth of nonmagnetic plate can be extended to 25mm.