磁致伸缩力传感器依靠材料磁化强度的改变来表征外部力载荷的大小,研究了基于Fe-Ga合金磁致伸缩逆效应的力传感模型,采用三维有限元方法对力传感磁路进行了优化与设计。为了研究不同磁场和负载对材料磁化强度的影响,以均质能量公式为基础,在均质能量公式中引入以应力和磁场为自变量的吉布斯自由能函数,建立了描述合金磁化强度随应力变化关系的模型。为对模型进行验证,建立了一套磁致伸缩力传感特性测试系统,分别对Fe-Ga合金和Terfenol-D力传感特性进行测试与对比,验证试验表明所建立的模型可以较好预测磁化强度的变化,并且可以预测偏置磁场的影响。在Fe-Ga合金与Terfenol-D的对比试验中发现,Fe-Ga合金对偏置磁场更为敏感,并且磁滞非线性较Terfenol-D更小,由于无退火应力,Terfenol-D在偏置较低时出现负方向的磁化强度。
The magnetization model of a magnetostrictive force sensor was studied based on Fe-Ga alloy. The magnetic path of the sensor was optimized with 3D finite element method. Simulation results showed that the field distribution became linear when the magnetic path was optimized. In order to analyze the influence of biased field and loaded stress on material magnetization, the magnetization model was developed based on the homogeneous energy equation. The magnetic field and stress were taken as the independent variables in the Gibbs free energy formula thus the model could respond to both field and stress. The model was numerically solved using Newton's iteration method. In order to verify the model, a testing system was developed and both Fe-Ga alloy and Terfenol-D were tested. Comparisons of simulations and experiments showed that the proposed model could predict the changing of the magnetization properly. The influence of the biased field could be predicted as well. Comparisons of Fe- Ga alloy and Teffenol-D showed that Fe-Ga was more sensitive to the biased field and the hysteresis nonlinearity was lower than Terfenol-D. Since there is no annealed stress in Terfenol-D, it is observed negative magnetization when the material is subjected to cyclic stress with low biased field.