Zhang Xin, Xu Jiawen, Yan Ruqiang
Jiangsu Key Lab of Remote Measurement and Control, School of Instrument Science and Engineering, Southeast University, Jiangsu 210096, China.
International Machinery Center, School of Mechanical Engineering, Xi'an Jiaotong University, Shaanxi 710049, China.
Rev Sci Instrum. 2020 Aug 1;91(8):085111. doi: 10.1063/5.0016798.
Polyvinylidene fluoride (PVDF) patches have extremely small Young's modulus and piezoelectric coefficients. They are usually chosen as sensors in the structural impedance measurement for health monitoring. In this paper, a novel method is demonstrated for structural impedance measurement using PVDF patches as actuators and sensors. The impedance of the host structure is decoupled from the capacitance impedance of the piezoelectric transducer by using one of the patches as the actuator and the other as the sensor. Phase sensitive detection is then adopted to recover weak impedance signals in the experimental studies. This technique enables measurement of the resonant frequencies and further identification of the health condition of the host structure. The superiority of this method is illustrated theoretically comparing to the conventional impedance-base method. A prototype consisting of a metal cantilever with two PVDF patches is fabricated and tested. Experimental results demonstrate the effectiveness of the proposed method in the detection of the resonance of the substrate precisely with respect to FEM simulation and the results under base-movement excitations. Moreover, mass change induced impedance shifting can be obtained.
聚偏二氟乙烯（PVDF）贴片具有极小的杨氏模量和压电系数。它们通常被选作用于健康监测的结构阻抗测量中的传感器。本文展示了一种使用PVDF贴片作为致动器和传感器进行结构阻抗测量的新方法。通过将其中一个贴片用作致动器，另一个用作传感器，将主体结构的阻抗与压电换能器的电容阻抗解耦。然后在实验研究中采用相敏检测来恢复微弱的阻抗信号。该技术能够测量共振频率并进一步识别主体结构的健康状况。与传统的基于阻抗的方法相比，从理论上说明了该方法的优越性。制作并测试了一个由带有两个PVDF贴片的金属悬臂组成的原型。实验结果表明，所提出的方法在精确检测基板共振方面相对于有限元模拟以及在基座运动激励下的结果是有效的。此外，可以获得质量变化引起的阻抗偏移。
