The lift-off effect analysis of flexible differential pick-up koch fractal eddy current probe  

柔性差测量科赫分形涡流传感器提离效应分析

作　　者：CHEN Guolong FAN Le ZHANG Shuaishuai HAN Yu LI Yixin ZHANG Yanlong 陈国龙;樊乐;张帅帅;韩瑜;李奕欣;张雁龙(兰州理工大学机电工程学院,甘肃兰州730050)

机构地区：[1]School of mechanical and electrical engineering,Lanzhou university of technology,Lanzhou 730050,China

出　　处：《Journal of Measurement Science and Instrumentation》2024年第4期432-444,共13页测试科学与仪器（英文版）

基　　金：supported by the National Nature Science Foundation of China(Nos.62471206,52467002)。

摘　　要：This study utilized finite element simulation and experimental methods to investigate the evolution of crack detection performanceof a flexible differential fractal Koch eddy current probe at different excitation frequencies as the lift-off distance increases.As the lift-off distanceincreased,the distribution shape of induced eddy currents changed,leading to reduced similarity in the shape of the excitation coil and an expandeddistribution range of induced eddy currents,ultimately resulting in weakened output signal strength.The experimental results showed that forexcitation frequencies of 10 kHz,20 kHz,50 kHz,100 kHz,200 kHz,500 kHz,and1000 kHz,the maximum lift distances of the real partof the output signal when cracks were detected were 5.0 mm,7.0 mm,8.0 mm,8.0 mm,8.0 mm,6.5 mm,and 4.0 mm,respectively.Theimaginary parts were 6.5 mm,6.5 mm,7.5 mm,5.5 mm,8.0 mm,6.5 mm,and 6.5 mm,respectively.本研究采用有限元仿真和实验方法,探究了柔性差测量分形科赫涡流传感器在不同激励频率下随着提离距离增加对裂纹检测性能的演化规律,以及传感器在可检测到裂纹时的最大提离距离。随着提离距离的增加,感应涡流的分布形状发生变化,导致激励线圈形状的相似性降低,感应涡流的分布范围扩展,最终导致输出信号的强度减弱。实验结果显示,当激励频率分别为10 kHz、20 kHz、50 kHz、100 kHz、200 kHz、500 kHz和1000 kHz时,传感器输出信号的实部在检测到裂纹时的最大提离距离分别为5.0 mm、7.0 mm、8.0 mm、8.0 mm、8.0 mm、6.5 mm和4.0 mm;虚部则分别为6.5 mm、6.5 mm、7.5 mm、5.5 mm、8.0 mm、6.5 mm和6.5 mm。

关 键 词：eddy current testing lift-off effect nondestructive testing crack detection fractal geometry 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]