基于有限元法的输气管道漏磁场分析

ANALYSIS OF MAGNETIC FLUX LEAKAGE FIELDS FOR GAS TRANSMISSION PIPELINE BASED ON FINITE ELEMENT METHOD

漏磁检测是输气管道无损检测的常用方法之一,也是实现管道在役检测的有效方法。建立了输气管道漏磁检测的实体模型和有限元分析的数学模型;推导出适合齐次自然边界条件下泊松方程的有限元方程;通过对输气管道缺陷进行有限元方法分析计算,可知有限元法能分析计算任意形状缺陷的漏磁场,能方便地建立大量形状不同尺寸不一的缺陷识别库,给出了磁场强度矢量图、磁力线分布图和漏磁场分析结果。同时,利用有限元法分析计算了不同尺寸不同形状缺陷的漏磁场,得出了随着缺陷宽度、深度的增加峰峰值也随着增大的结论。分析结果可为缺陷的定量检测打下基础。

Magnetic flux leakage(MFL) testing is one of common methods for non-destructive testing of gas transmission pipeline and an effective method of real time detecting of gas transmission pipeline.The noumenal model for MFL testing of gas transmission pipeline and the mathematical models for finite element analysis were established.The Poisson's finite element equations in the homogeneous natural boundary conditions were derived.After calculating and analyzing defect by means of finite element method,the vector map of magnetic field intensity,the distribution chart for the flux lines,and the results of magnetic leakage fields were introduced.After calculating and analyzing all sorts of defects by means of finite element method,the result was drawn that the increment of peak-peak values were caused by escalation of defect width or depth.The obtained result is the foundation of the quantitative detection of defects.