管道外壁可变径漏磁检测数值模拟与分析

MFL Numerical Simulation and Analysis of Diameter-variable Magnetization Structure in Pipelines

利用有限元方法建立静态管道外可变径漏磁检测的三维模型,该检测模型有3个分离式的励磁结构,可以调整励磁结构之间相对角度,满足不同管径的检测需要。建立不同几何尺寸缺陷、被检测管壁厚度等模型,通过有限元软件计算得到各自条件下漏磁场轴向分量和径向分量峰值分布曲线,通过对比分析得出:缺陷的几何尺寸影响漏磁场分布,且两者之间存在一定的关系,如缺陷深度在一定直径范围内与漏磁信号成近似线性关系;漏磁场随着缺陷直径增大先增大后减小,可凭借采集信号峰-峰值间隔距离,定性地判断缺陷的直径范围。

The 3D model for testing magnetic flux leakage（MFL） of static diameter-variable pipelines was built with finite element method（FEM）,and the relative angles among three separated magnetization structures of this model were adjusted to satisfy pipelines detection of variable diameters;and the MFL models for different defects and wall thickness were established to produce the axial component and radial component peak distribution curve.The comparative analysis shows that the physical dimension of defects can influence the distribution of MFL field,and a certain relationship between them exists,Experimental results indicate that any 3mm defect and a 20% metal loss can be detected.