基于正弦力激励的预紧压电式力传感器的研究

为了校准预紧的压电式力传感器动态灵敏度并研究其频响特性和预紧结构的设计,首先介绍了正弦力激励的方法并建立校准数学模型。分别在传感器正立和倒立安装方式下进行测试,通过对比试验研究传感器端部等效质量引入的惯性力对传感器动态灵敏度的影响。然后根据传感器固有频率的落球测试方法,将传感器和附加质量块安装于振动系统。通过白噪声激励得到系统安装谐振频率,进而研究传感器有效频率范围和测量精度与安装谐振频率的关系。最后通过理论分析,说明传感器非对称设计的原因。试验结果表明,当附加质量块质量约为传感器质量的121倍时,可忽略端部等效质量对灵敏度标定的影响；压电式力传感器固有频率高达46kHz,但其有效使用频率范围受安装谐振频率限制,当试验频率与安装谐振频率比 时,压电式传感器精度等级为1%；传感器两端等效质量不同,预紧结构是非对称的,用于动态测试时要将端部等效质量轻的一端连接到被测物体。本研究结果可为开展传感器的现场标定和预紧结构的设计提供理论依据。

Research on preloaded piezoelectric force sensor based on sinusoidal force excitation

In order to calibrate the dynamic sensitivity of the preloaded piezoelectric force sensor, study its frequency response characteristics and the preloaded structure design, a sinusoidal force excitation method is introduced to establish the calibration mathematical model. The test is conducted in the upright and inverted installation modes of the sensor, respectively.The influence of the inertial force introduced by the equivalent mass at the sensor end on the dynamic sensitivity calibration is studied through comparative tests. Then. the sensor and the additional mass are installed in the vibration system according to the falling ball test method which is based on measuring the natural frequency The system installation resonant frequency is obtained by white noise excitation. The relationship between the installation resonant frequency and the effective frequency range as well as the measurement accuracy is studied. Finally, , the reason for the asymmetric design of the sensor is explained by theoretical analysis. The test results show that when the additional mass is about 121 times of the sensor, the effect of the end equivalent mass on the sensitivity calibration can be ignored; The natural frequency of piezoelectric force sensor is up to 46kHz, but its effective frequency range is limited by the installation resonant frequency. When the ratio of test frequency and the installation resonant frequency , the accuracy grade of piezoelectric force sensor is 1%; The equivalent mass at both ends of the sensor is different, and the preloading structure is asymmetric for the end with light equivalent mass could be connected to the testing objectduring for dynamic test,. The research results provide a theoretical basis for the sensor field calibrationand the preloading structure design.