管道裂纹远场涡流检测的三维仿真研究

Research on 3-D Simulation of Remote Field Eddy Current Detection for Pipeline Cracks

远场涡流检测技术具有内、外表面敏感度相同的优点,因而适合铁磁性油气长输管道中裂纹缺陷的无损检测。利用数值方法对远场涡流检测过程进行了仿真,给出了检测信号与裂纹几何尺寸之间的量化关系。首先,根据麦克斯韦方程组推导出3维远场涡流磁场分布的数学表达式。然后,由ANSYS软件建立3维远场涡流有限元仿真模型,并分析磁场在管壁内的分布特性。最后,通过3维仿真模型估计轴向裂纹的几何尺寸参数(长度、深度、宽度)对远场涡流检测信号的影响,并就它们之间的对应关系展开讨论。仿真结果为实际管道裂纹检测器设计、远场涡流探头的优化和裂纹量化评估提供了有效参考。

The remote field eddy current （RFEC） technique, with the merit of the same sensitivity to the internal and external surface defects, has been adapted for the detection of stress corrosion cracks （SCC） that are located in ferromagnetic oil and gas long-distance pipelines. To simulate the detection process of RFEC by numerical method, a quantitative relationship between SCC geometric parameters and RFEC detection signals was proposed. Firstly, according to Maxwell equations, the three-dimension （3-D） RFEC equation was deduced. Then the 3-D RFEC simulation model was established in ANSYS, through which the distribution of the eddy current magnetic field in the pipeline was analyzed. Finally, the impacts of the axial SCC geometric parameters, such as length, depth and width, on RFEC detection signals were evaluated by the 3-D finite element （FE） simulations, and the relations between them were discussed. All the simulation results are represented for the effective reference of improving the practical RFEC inspection of cracks.