考虑应力波衰减特性的磁致伸缩位移传感器的输出特性与实验

Output characteristics and experiments of magnetostrictive displacement sensor considering the attenuation characteristic of stress wave

为提高磁致伸缩位移传感器的测试量程,需要对传感器的输出特性进行研究,以期获得更大的检测信号。针对应力波在传播过程中的衰减直接影响检测信号幅值的问题,从声压强度与声波峰值的关系出发建立了含有传播距离的输出电压模型,确定了输出电压随传播距离呈指数衰减的规律。为了测试输出电压随传播距离变化的关系,提出通过应力波来回多次反射来得到衰减后的电压幅值的方法,去掉波导丝两端阻尼,永磁体和检测线圈的位置不变,可以避免波导丝的不均匀性对输出电压的影响以及较长波导丝所需激励电压过高的问题。搭建了传感器输出信号衰减测试平台,对线径为0.5 mm,应力波衰减系数为0.132 3 Np·m^（-1）的Fe-Ga丝进行测试,基于所提实验方法,测得应力波传播距离为0.312~4.266 m时,偏置磁场分别为7.5和10 k A/m对应的输出电压的变化范围分别为138~79.6 m V和172~99.5 m V。从实验上验证了输出模型的准确性,应用此模型可以对传感器的输出电压值和量程进行预测。

In order to improve the measuring range of magnetostrictive displacement sensor,the output characteristics of the sensor need to be studied to obtain larger detection signals. In view of the problem that the attenuation of stress wave directly affects the amplitude of detection signal,the output voltage model with propagation distance is established based on the relationship between the sound pressure intensity and the peak value of acoustic wave. And the law of output voltage decreasing exponentially with propagation distance is determined. To test the relationship between the output voltage and the propagation distance,a method of obtaining the voltage amplitude after attenuation is put forward by repeated reflection of stress waves. The damping at both ends of the waveguide wire is removed and the positions of the permanent magnet and the detection coil are fixed,which can eliminate the effect of the inhomogeneity of the waveguide wire on the output voltage and the excessively high exciting voltage of the long waveguide wire. The sensor output signal attenuation test platform is set up. The Fe-Ga wire is tested with a diameter of 0. 5 mm and the stress wave attenuation coefficient of 0. 132 3 Np·m^（-1）. Based on the proposed experimental method,it is measured that when the propagation distance of the stress wave is increases from 0. 312 to 4. 266 m,the corresponding output voltage ranges from 138 to 79. 6 m V and 172 to 99. 5 m V when the bias magnetic field is 7. 5 and 10 k A/m,respectively. The accuracy of the output model is verified experimentally and the model can be used to predict the output voltage and range of the sensor.