点探头涡流无损检测中磁介质作用机理研究

Research on Eddy Current Nondestructive Test Using Point Probe with Magnetic Core

结合实际涡流无损检测应用中的含磁介质点探头的特点,分析了探头中磁介质引入的各种附加效应及其对缺陷阻抗的影响。通过引入等效电流的概念,讨论了磁介质对涡流场的作用,建立含磁介质点探头涡流无损检测模型,并给出含磁介质探头周围的电磁场方程,求得均匀半无限导体系统的磁矢量势分布和导体中涡流、电场强度分布。通过实例,计算了非铁磁性导体中无缺陷时探头信号与提离高度的关系、存在缺陷时探头阻抗变化的特点。理论计算与实验结果基本吻合。

The eddy probe for defect is an important implement in nondestructive testing, it is necessary to develop a theory of eddy current field around probe with magnetic core and correspondent formula to compute the resistance of the probe. Using dyadic Green＇s function to compute the three-dimensional eddy current field around the probe is developed when detect exist in conductor. The resistance computing and other correspondent formulas are provided. The relationships between the height of lifting off of the probe and its resistance are provided when there is a detect or not in testing conductor.