Damage Detection Using Piezoelectric Admittance Approach with Inductive Circuitry

The impedance/admittance-based damage detection has been recognized to be sensitive to small-sized damage due to its high frequency measurement capability. Low-cost measurement circuit has previously been explored to extract the piezoelectric impedance/ admittance curves by using a resistor that is serially connected with the piezoelectric transducer, which enables a self-contained sensor unit. In this research, an innovative admittance-based damage detection scheme is proposed, which combines the key features of the low-cost impedance/admittance measurement circuit with those of the piezoelectric circuitry dynamics. In the new scheme, the piezoelectric transducer is integrated with an inductive circuit. The resonant effect of the inductive circuitry can greatly increase the measurement amplitude. Moreover, when the inductance is properly tuned, very significant dynamic interaction between the mechanical structure being monitored and the electrical circuitry will occur. This results in an order-of-magnitude amplification of the admittance change upon the occurrence of damage, which can yield much increased damage detection sensitivity. Extensive numerical and experimental investigations are carried out to demonstrate the new sensing system development.