可变径管道漏磁检测有限元仿真与实验研究

为了更好地支持压力管道检验，降低事故率，本文基于漏磁检测原理，利用有限元分析软件建立了管道外漏磁检测模型，对管道漏磁检测进行了仿真计算，得到了缺陷处漏磁场特征曲线，模拟了圆柱形缺陷对管道外壁漏磁场的影响，得出了不同参数缺陷对漏磁场的影响规律，并且基于理论和有限元计算结果试制了可变径管道外漏磁检测仪的样机，利用该检测仪对壁厚为8mm的带有人工缺陷的管道进行扫描检测，研究不同参数缺陷对漏磁场信号的影响规律。结果表明，所得结果与有限元仿真的结果吻合良好，且缺陷检测精度及效果满足要求，另外，检测装置对内外壁缺陷检测同样可行有效，适合特种设备（压力管道）检测的工程应用。

Finite element simulation and experimental research on diameter-variable pipeline magnetic flux leakage testing

In order to support the pressure pipeline inspection better and reduce the accident rate, a model of magnetic flux leakage testing outside pipeline was established by using the finite element analysis software based on the principle of magnetic flux leakage testing. The simulation calculation was conducted on the pipeline magnetic flux leakage testing, and the characteristic curves of magnetic flux leakage field at the defects were obtained. The influence of cylindrical defect on the magnetic flux leakage field outside pipeline was simulated, and the influence laws of defects with different parameters on the magnetic flux leakage field were obtained. A prototype of diameter-variable magnetic flux leakage testing device outside pipeline was manufactured based on the theory and the results of finite element calculation, and the testing device was applied to scan and test the pipeline with the wall thickness of 8 mm containing artificial defects, then the influence laws of defects with different parameters on the signals of magnetic flux leakage field were studied. It showed that the obtained results agreed well with the results of finite element simulation, and both the accuracy and effect of defect testing could meet the requirements. In addition, the testing device is feasible and effective for defect testing both inside and outside pipeline similarly, and it is suitable for engineering application of special equipment (pressure pipeline) testing.