Elevated Excitation Voltage Electrical Impedance Measurement System of Electro-Mechanical Impedance-Based Structural Health Monitoring

Abstract

A high excitation voltage electrical impedance measurement system (HEVEIMS) of electro-mechanical impedance (EMI)-based structural health monitoring (SHM) was established in this study. Low and middle voltage output options of ARB-1410 wave generation card were used to excite the PZT sensor. The electrical impedance signal of piezoelectric lead zirconate titanate (PZT) sensor was measured by DPO-4032 digital oscilloscope and voltage divisional impedance measurement circuit. Circular PZT sensor of 14 mm diameter and 0.2 mm thickness was used in this study. In the frequency ranges of 10–60, 100–150, 200–250, 250–300, and 300–350 kHz, the modulus, real, and imaginary part of the PZT impedance were measured with HEVEIMS and WK6500B precision impedance analyzer, respectively. Comparison of the results with the two instruments indicates that the measurement accuracy of the HEVEIMS established in this paper is quite high. A 1.2 mm diameter hole drilled at 1000 mm from the PZT center was further tested with EMI technique, at various excitation voltages (EVs) from 1 to 30 V by HEVEIMS. At high EV, the sensitivity of EMI technique increases to some extent due to the increase of PZT generation force.