激励电压对压电阻抗法检测灵敏度的影响

Influence of Excitation Voltage on Testing Sensitivity of Electro-Mechanical Impedance Method

研究了锆钛酸铅压电陶瓷(lead zirconate titanate piezoelectric ceramic,简称PZT)传感器的激励电压与压电阻抗法(electro-mechanical impedance,简称EMI)结构健康监测技术灵敏度之间的关系。借助WK 6500B精密阻抗分析仪及自行搭建的高激励电压电阻抗测试系统(high excitation voltage electrical impedance measurement sys-tem,简称HEVEIMS),在0.01～20V之间8种不同激励电压下,对尺寸为1250mm×100mm×3mm铝梁结构上距离PZT传感器1 000mm的直径为1.2,2.5和3.5mm的通孔损伤进行了检测。研究结果表明,激励电压与检测灵敏度之间的关系是非单调的。在1～10V范围内,提高激励电压能够显著增大EMI方法的检测灵敏度。高激励电压下PZT电阻抗信号中非线性成分增多是导致EMI方法检测灵敏度升高的主要原因。研究结果不但为EMI检测中激励电压的选取提供了参考,也为明确激励电压与检测灵敏度之间的相关关系提供了数据支持。

The relationship between excitation voltage of lead zirconate titanate piezoelectric ceramic(PZT) sensor and testing sensitivity of electro-mechanical impedance(EMI) based structural health monitoring method is quantitatively studied.The specimen used in this study is aluminum beam structure with the size of 1 250 mm×100 mm×3 mm.Three hole damages with the diameters of 1.2,2.5 and 3.5 mm are drilled at 1 000 mm from the PZT center.The sensitivity of EMI method is investigated at 8 kinds of excitation voltages from 0.01 to 20 V,with WK 6500B precision impedance analyzer and self-established high excitation voltage electric impedance measurement system(HEVEIMS).The results show that the relation between excitation voltage and EMI sensitivity is not monotonic.In the voltage range of 1-10 V,the sensitivity of EMI method increases significantly with the increase of excitation voltage.The increasing of non-linear signals in PZT electric impedance spectrum at high excitation voltage is the main reason for the increase of EMI sensitivity.This study not only gives a reference for the selection of excitation voltage,but also provides a data support for the clarification of the relation between excitation voltage and EMI sensitivity.