油管缺陷漏磁场有限元分析

FINITE ELEMENT MODEL OF MFL TESTING FOR OIL TUBE

采用有限元技术,建立了油管缺陷漏磁场的静态和瞬态仿真模型。通过对励磁磁场的均匀性、检测速度和缺陷尺寸三种影响因素的仿真分析,比较了静磁场模型和瞬态模型的仿真结果和效率。静磁场模型求解效率高、占用的计算资源少,但是随着检测速度的增大,求解结果明显偏高。瞬态模型能降低速度引起的误差问题,但需要大量的计算资源。给出了用静磁场模型分析缺陷漏磁场应满足的条件。

Using finite element method (FEM), the magnetostatic and transient emulation models of magnetic flux leakage (MFL) of oil tube are established. Parameters of the exciters, inspecting velocity and size of defects are analyzed by using two models respectively. Compared with static and transient simulation results, the limitation that uses magnetostatic model to simulate MFL of defects of oil tube is concluded. When the velocity is over 5m/s, simulating with magnetostatic model suffers somewhat inaccuracy. Although accurate results are usually obtained with transient model, the long elapsed time during the simulation process consumes a lot resources. At last, the conditions of using magnetostatic model to simulate MFL of defects are presented.