Enhanced Piezoelectric Impedance Approach for Damage Detection With Circuitry Integration

Piezoelectric impedance-based damage detection approach has been recognized to be sensitive to small-sized damage, as the impedance information can be measured at relatively high frequency range. To enhance this approach, recently an innovative scheme is developed by integrating the inductive circuitry serially with the piezoelectric transducer. With the resonant effect due to such inductive circuitry integration, the measurement amplitude is greatly amplified. It has been identified that the change of admittance measurement before and after damage occurrence is increased by an order-of-magnitude, which yields much increased detection sensitivity. In this research, we first attempt to enhance this inductive circuitry scheme by integrating the negative capacitance element. With the peak magnitude of the curve of the admittance change remaining high, the magnitude of the admittance change away from the resonances is greatly increased, which means the amplification effect of the inductive circuitry becomes effective in a wider frequency range. Then we make further improvement by connecting the resistor (used to facilitate the admittance measurement) parallel with the inductor. This results in the amplification of the voltage across the resistor, and thus further increases the signal-to-ratio of admittance measurement. Extensive numerical and experimental studies are carried out to demonstrate the effectiveness of the proposed enhancements.