交流电磁场检测数值仿真及其信号敏感性分析

Numerical simulation on alternating current field measurement and sensitivity analysis of detected signal

基于开发交流电磁场检测 (ACFM )可视化技术的需要 ,采用数值模拟方法对ACFM技术进行了探讨。以ANSYS软件系统为工具 ,建立了ACFM数值仿真模型。该模型解决了利用裂纹物理参数和几何厚度建模以及裂纹导致的奇异性处理两方面的问题 ,能够精确获得任意形状裂纹的电磁场分布。分析了材料性质与提离两种因素对磁场分布影响的敏感性。仿真结果表明 ,ACFM对磁导率、电导率和提离的变化均不甚敏感 ,与涡流检测技术相比 ,更适合于低碳钢的裂纹检测。此研究为开发ACFM装备的数字化样机提供了理论依据。

In order to develop the visualization technique for alternating current field measurement (ACFM), the application basis of ACFM was investigated with a numerical simulation method. A general digital model of ACFM was established, by means of the ANSYS CAE system. In the model, the physical parameters and gap thickness of a crack were well modeled, and the singularity resulted from crack was well treated. This model can be used to determine the magnetic distribution in the vicinity of any crack with irregular shape. The effects of lift-off and material properties on the magnetic distribution were evaluated and discussed by using the model. The numerical simulation results show that ACFM is not sensitive to the changes of magnetic conductivity, electric conductivity and lift-off. It is more feasible to detect the crack on the mild steel, compared with the eddy current testing. The researched conclusions may provide a theoretical basis for the development of virtual prototype of ACFM visualization products.