基于磁机械效应的铁磁材料漏磁检测数值模拟

为更准确地描述材料的非线性磁机械耦合效应，以非线性磁致伸缩应变方程、有效场理论和能量平衡方程等为基础提出新的磁弹性耦合模型与变刚度模型，分析了铁磁材料的磁机械效应和变刚度效应，并利用数值分析软件将非线性磁化模型的理论结果与仿真过程进行耦合。结果表明，仿真得到的缺陷泄漏场分布与已有研究结果一致，验证了所提出模型与仿真方法的可行性和准确性。分析了应力、缺陷尺寸和缺陷位置对表面磁场的影响，结果表明：在拉伸载荷作用下，试样表面法向磁场信号呈类S形曲线，切向信号呈类锥形曲线，其极值均随载荷增加先减小后增大；试样存在缺陷时，不同采集路径上获取的信号存在很大差异，缺陷边缘路径上的漏磁场峰值与缺陷长度呈负相关，而峰值距离和跨度却相反，在远离缺陷的采集路线上，漏磁场信号的峰值和跨度均与缺陷长度呈正相关。

Numerical simulation of magnetic flux leakage detection of ferromagnetic materials based on magneto-mechanical effect

To describe the nonlinear magneto-mechanical coupling effect of materials more accurately, a coupled magneto-elastic model and a variable stiffness model were proposed based on nonlinear magneto-strictive strain equation, effective field theory, and energy balance equation. The magneto-mechanical effects and variable stiffness effects of ferromagnetic materials were studied, and the theoretical results of the nonlinear magnetization model were coupled with the simulation process using numerical analysis software. The results showed that the defect leakage field distribution obtained by the simulation was consistent with the existing research results, which verified the feasibility and accuracy of the proposed model and simulation method. The effects of stress, defect size, and defect location on the surface magnetic field were also analyzed. The results showed that under the action of tensile load, the normal magnetic field signal on the surface of the sample was like an S-shaped curve, and the tangential signal was like a conical curve, and its extreme values first decreased and then increased with the increase in the load. When there was a defect in the sample, the signals obtained on different acquisition paths were very different, and the peak value of the leakage magnetic field on the defect edge path was negatively correlated with the defect length, but the peak distance and span were opposite. On the collection route far from the defect, the peak value and span of the leakage magnetic field signal were positively correlated with the defect length.