三轴交流漏磁检测的有限元仿真

Finite element simulation of three axis AC magnetic flux leakage detection

管道是能源输送的重要手段,一旦出现损坏发生泄漏等事故会对生态和社会造成严重的后果。针对传统交流漏磁方法检测到的一维漏磁信号对缺陷识别度不高的问题,提出三轴交流漏磁检测方法,利用Ansoft Maxwell软件对管道缺陷交流漏磁检测进行三维有限元仿真,并研究其趋肤效应和提离效应。结果表明:增加漏磁场检测分量对缺陷的识别有很大的提高,当励磁频率大于1KHz时,趋肤深度达到一个稳定值,继续增加励磁频率对检测没有很大的提高。对提离效应进行分析,得到传感器提离值和磁化器提离值的对应关系,并且当传感器提离值比磁化器提离值高出0~1mm时,缺陷漏磁信号的检测比较稳定。

Pipeline was an important means of energy transport. It would cause serious ecological and social consequences if the leakage accident happened. The defect was not highly recognized by one-dimensional magnetic flux leakage signal detected by the traditional method of AC-MFL, in this case that three axis AC magnetic flux leakage testing method was proposed. And a finite element of AC-MFL detection system was build adopting Ansoft Maxwell program to simulate the 3-D static situation, then the skin effect and the lift-off effect were analyzed. Results show that the identification of defects had greatly improved by increasing the leakage magnetic field detection component. The skin depth reached a stable value when the excitation frequency was greater than1 KHz, which meant that the increase of excitation frequency would not greatly improved the detection results. The correspondence between the sensor and magnetizer lift-off value was obtained, and it concluded that MFL signal would be more stable if the sensor lift-off value was higher than magnetizer`s from 0 to 1 mm.