激励磁场对力磁耦合作用的强化机制研究

Study on Strengthening Mechanism of Excitation Magnetic Field to Stress-magnetization Coupling Effects

力磁耦合作用是金属磁记忆检测等电磁无损检测技术的基础。为了探明外加激励磁场在不同应力水平下对力磁耦合作用的影响机制,从磁导率与应力及环境磁场变化关系的角度,在理论上计算了外加激励磁场下力磁耦合作用下与力和磁单独作用下的表面磁场强度之差ΔH,并推导出该差值随着拉应力的增大而增大的结论。用预制缺陷的45钢试样进行对照试验,发现激励磁场对力磁耦合作用的影响ΔH是随着应力的增大而呈类似指数形式递增的。经设计的正交试验验证,激励磁场与应力对磁信号的交互耦合作用显著,且在受力过程中激励磁场对信号的作用水平最大,这与理论分析结果吻合。说明外加激励磁场对力磁耦合作用起到了一定的强化作用。

The stress-magnetization coupling effect was the basis of metal magnetic memory detection and other electromagnetic nondestructive testing technology. To investigate the mechanism of the excitation magnetic field to stress-magnetization coupling effect under different stress levels, a differential value AH, was calculated theoretically fi＇om the relationship of permeability and stress and environmental magnetic field, which was the difference between the magnetic field strength affected by stress or magnetism interactively and by them individually. It was deduced that AH increased with the increases of tensile stresses. A control test was conducted with a prefabricated defective 45 steel sample, and it is found that AH, characterized the effects of the excitation magnetic field on the stress-magnetization coupling, increases exponentially with the increases of the stresses. And the orthogonal experiment was designed to verify that the interactions between the excitation magnetic field and the stress on the magnetic signals were significant. In the loading processes, the excitation magnetic fields were the greatest impacts on the signals. These are consistent with the theoretical analyses. The results show that excitation magnetic field plays a certain role in strengthening the stress-magnetization coupling effects.