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为研究运输管道缺陷的漏磁(MFL)信号特征,采用ANSYS软件进行管道缺陷漏磁检测的三维有限元数值仿真。首先建立漏磁检测分析装置的数值模型,进行三维静态情况的数值计算,获得不同缺陷所产生的漏磁信号,然后将这些数据与试验结果进行比较分析。在此基础上,分析缺陷深度、缺陷直径以及传感器提离值对漏磁信号参数的影响。结果表明:磁通密度轴向分量B y的幅值能够用于衡量缺陷的深度,可依据B y的宽度和磁通密度径向分量B z的峰峰间距来定量识别缺陷直径;传感器的提离值对缺陷漏磁场的影响很大,为使测得的漏磁信号可靠并能测得深度较小的缺陷,传感器的提离值应设定为1.5~3 mm。
In order to study the MFL signal characteristics of transportation pipeline defects, ANSYS software was used to simulate the three-dimensional finite element numerical simulation of pipeline leakage magnetic flux leakage testing. Firstly, the numerical model of magnetic flux leakage testing and analyzing device is set up, the numerical calculation of static state in three dimensions is carried out, and the magnetic flux leakage signal generated by different defects is obtained. Then the data are compared with the test results. Based on this, the influence of defect depth, defect diameter and sensor lift-off value on the MFL signal parameters was analyzed. The results show that the amplitude of magnetic flux density axial component B y can be used to measure the defect depth. The defect diameter can be quantitatively identified according to the width of B y and the peak-to-peak spacing of radial component B z of magnetic flux density. The value of the impact on the leakage magnetic field greatly affected, in order to make the measured flux leakage signal is reliable and can detect the depth of smaller defects, the sensor lift-off value should be set to 1.5 ~ 3 mm.