管道复合缺陷漏磁信号特征分析

Analysis of magnetic flux leakage signal characteristics of pipeline complex defects

基于漏磁检测技术基本原理,采用有限元方法,运用COMSOL软件对管道复合缺陷裂纹群和凹坑群的漏磁信号进行了仿真模拟。结果表明:对于裂纹群,随着裂纹条数的增加,磁通密度径向分量B_(x)峰值和轴向分量B_(y)幅值显著增大,且B_(x)峰值间距向两侧偏移,B_(y)波形宽度略有增大;当金属损失体积相同时,磁通密度径向分量和轴向分量峰值不仅与缺陷尺寸有关,还与缺陷分布形式相关。对于沿轴向和周向分布的复合凹坑,当凹坑相互叠加时,在凹坑重叠部分发生漏磁信号的变化;当凹坑相互分离,两凹坑的漏磁信号相互独立,且信号强度不随凹坑距离的继续增加发生明显变化。

Based on the basic principle of magnetic flux leakage(MFL)detection technology,the finite element method and COMSOL software were used to simulate the magnetic flux leakage signals of crack group and pit group with composite defects of pipeline.The results show that for the crack group,with the increase of crack strips,the amplitude of radial component B_(x) and axial component B_(y)of the flux density increase significantly,and the space of peak valuesof B_(x) shifts to both sides,and the width of B_(y)waveform increases slightly.When the metal loss volume is the same,the peak values of the radial and axial components of the flux density are not only related to the defect size,but also related to the defect distribution.For the compound pits distributed along the axial and circumferential directions,when the pits are superposed with each other,the magnetic flux leakage signal changes in the overlapping part of the pits.When the pits are separated from each other,the magnetic flux leakage signals of the two pits are independent of each other,and the signal strength does not change significantly with the increase of the pit distance.This provides a theoretical basis and reference for the analysis of the leakage signal characteristics of the defect group.