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在基于磁偶极子解析模型的漏磁检测正演问题中,已有文献关于磁荷在缺陷壁上均匀分布的假设不成立。磁化后的缺陷材料相当于磁媒质,考虑到材料的非线性,磁荷在整个缺陷材料内及缺陷壁上非均匀分布。所以,该文从磁化后整个缺陷材料区域中磁化强度的分布出发,将单位体积内的磁偶极矩的矢量和等效为一个磁偶极矩,并作为磁场源点。从磁偶极子模型出发,推导出任意单元的磁媒质在场点处产生的磁场的积分公式,将整个缺陷材料的积分问题转换为对若干单元进行积分后的叠加。对于任一单元的积分问题,采用数值积分方法求解,并将该方法扩展到整个源区单元,最终整理得到任一场点处磁场的计算方程。通过COMSOL多物理场仿真软件搭建缺陷材料的漏磁场仿真模型,将仿真结果与计算结果进行对比分析,验证该方法的有效性。
In the forward problem of magnetic flux leakage detection based on the analytic model of magnetic dipole, the assumption about the uniform distribution of magnetic charge on the defect wall does not hold. Magnetized defect material is equivalent to magnetic media, taking into account the material nonlinearity, the magnetic charge in the entire defect material and the defect wall unevenly distributed. Therefore, starting from the distribution of magnetization in the entire defect material area after magnetization, the vector of the magnetic dipole moment in a unit volume is equivalent to a magnetic dipole moment and serves as a magnetic field source point. Based on the magnetic dipole model, the integral formula of the magnetic field generated at the magnetic field of arbitrary unit is deduced, and the integral problem of the entire defect material is transformed into the superposition of several units. For the integral problem of any unit, the numerical integration method is used to solve the problem. The method is extended to the entire source area unit and finally the calculation equation of the magnetic field at any point is obtained. The COMSOL multiphysics simulation software was used to build the leakage magnetic field simulation model of the defect material. The simulation results were compared with the calculated results to verify the effectiveness of the method.