钻杆在线漏磁探伤系统探头静磁力的数值模拟

Numerical Simulation of the Static Magnetic Force of Probe on Drillpipe Online MFL Detection System

永磁探头对钻杆的静磁力将直接影响探头总成对钻杆的吸附程度。利用ANSYS有限元分析软件对探头总成与钻杆进行了三维建模,并结合虚功法对探头与钻杆之间的静磁力进行了数值模拟分析;同时还定量分析了不同气隙厚度与不同磁轭厚度对探头静磁力的影响。分析结果表明,由于钻杆圆柱面的存在,探头与钻杆之间气隙厚度对其静磁力将产生非线性影响;探头磁轭厚度的改变将导致探头与钻杆之间静磁力成线性变化,而且气隙厚度的变化对探头与钻杆之间的静磁力的影响要大于磁轭厚度变化对其的影响。该项研究结果对钻杆漏磁检测中探头的设计有一定的参考价值。

The static magnetic force of the magnetic probe toward drillpipe will directly affect the adsorption de- gree of drillpipe. The ANSYS finite element analysis software was used to conduct the three-dimensional modeling of the probe assembly and drillpipe. In combination of the virtual work method, a numerical simulation analysis of the static magnetic static force between the probe and drillpipe was carried out. Meanwhile, a quantitative analysis of the effects of different air gap thicknesses and different magnetic yoke thicknesses on the probe＇ s static magnetic force was conducted. The analysis shows that, due to the existence of drillpipe＇ s cylindrical surface, the gas gap thickness between the probe and drillpipe will have a nonlinear effect on the drillpipe＇ s static magnetic force. The change of the yoke thickness will cause the linear variation with regard to the static magnetic force between the probe and drillpipe. Moreover, the air gap thickness change has greater effect on the static magnetic force than the yoke thickness change.