Analysis of stress-magnetic coupling effect in weak magnetic environment

Metal magnetic memory (MMM) signals are difficult to be analyzed due to noise interference, which limits its practical engineering application. A method of improving the magnetic signals is proposed in this paper by placing the excitation device which generates a weak external magnetic field about 100 A/m. The effect of the external magnetic field on the magnetic signals is studied using both finite element method (FEM) and uniaxial tensile tests. Comparison of the test data with the simulation ones of stress-magnetic coupling shows that the magnetic signals are strengthened and the measurement sensitivity of the detection system is greatly improved through the external magnetic excitation. Moreover, the FEM result has a good agreement with the testing results of No.20 steel plate. The proposed method has laid a foundation for further practical engineering application.     

基于科赫雪花图形激励装置的涡流传感器工作原理分析

首次提出并设计了一种基于分形理论自相似结构的科赫雪花图形激励装置涡流传感器,对这种传感器的工作原理和物理模型进行了深入的分析,分析表明,基于分形结构激励线圈的涡流传感器,在多处具有涡流叠加效应,随着科赫雪花图形阶次的提高,这种涡流叠加效应越来越明显,分布密度不断增加,可以显著提高涡流传感器激励效果和检测灵敏度,从而提高对微小裂纹缺陷的检测能力.研制了实际装置,通过实验证了这一结论.     

弱磁激励下Q235钢的磁记忆检测

在不同弱磁场环境下对Q235钢平板试件进行静拉伸试验,利用TSC-1M-4磁检测仪原位测量试件表面的法向磁场,并分析磁场在拉伸过程中的变化规律。结果表明:强化弱磁激励可以减小干扰噪声的不利影响,改善检测效果。弱磁激励下,试件在弹性阶段出现应力磁化反转现象;塑性阶段保持磁化反转,磁场越过零点后沿反方向增大。并且,探讨了试件在弱磁激励下磁场梯度K与应力之间的相关性,为磁检测技术在铁磁材料损伤评估中的应用奠定了基础。