储罐罐壁缺陷检测爬壁机器人吸附机构的磁场分析

针对阶梯形变截面罐壁缺陷漏磁检测的可调节磁路问题,设计了吸附机构,实现吸附的同时对12mm厚罐壁进行有效磁化。基于传统的标准缺陷漏磁测量法,再结合剖分试件法,通过Ansys仿真和实验测量磁感应强度、背底磁场以及漏磁场特性,得到气隙值分别为5.5mm、6.5mm、7.5mm、8.5mm、9.5mm、10.5mm的漏磁场曲线。验证了磁路设计的正确性和仿真的可参考性,为通过仿真确定不同厚度钢板所需气隙提供依据。实验发现,钢板缝隙正上方漏磁场Bx和Bz存在峰值,随着气隙增大Bx峰值下降至5~10m T,偏离缝隙Bx骤减,钢板无缝隙处的背底磁场在20~30m T,钢板缝隙内磁化强度在771~893m T,且磁化较均匀。

Magnetic field analysis of absorption mechanism of MFL climbing-robot on tank wall

Aiming at the problem of adjustable magnetic circuit for defect MFL detection on ladder-shaped variable cross-section tank wall, absorption mechanism was designed, achieving the effective magnetization to 12mm thick wall at the same time for absorption. Based on the traditional standard defect MFL test, magnetic flux density, background magnetization and characteristics of leakage magnetic field were tested by Ansys simulation&experiment combining the specimen subdivision method, the magnetic characteristic curves for airgap of 5.5mm, 6.5mm, 7.5mm, 8.5mm, 9.5mm, 10.5 mm are obtained. Validity of magnetic circuit design was verified, the basis for airgap to different thickness steel plate by simulation were provided. The experiment result indicates that Bx and Bz peak of MFL field exist above the gap of steel plate; with the increasing of airgap, the decline to the peak of Bx magnetic characteristic curve varies from 5mT to 10mT, and Bx shows a sudden decrease deviating from the gap, the background magnetization of plate without defect is in the range of 20 to 30mT, and magnetization intensity in the gap is in the range of 771 to 893mT and uniform.