Piezoelectric Wafer Active Sensors for Structural Health Monitoring: State of the Art and Future Directions

Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive enablers for a large class of structural health monitoring (SHM) applications. The presentation will start with a brief review of PWAS physical principles and basic modeling. Then, the presentation will consider the several ways in which PWAS can be used for damage detection: (a) embedded guided-wave ultrasonics, i.e., pitch-catch, pulse-echo, phased arrays, thickness mode; (b) high-frequency modal sensing, i.e., the electro-mechanical (E/M) impedance method; (c) passive detection, i.e., acoustic emission and impact detection. Emphasis will be placed on recent developments. Special attention will be given to the mechatronics predictive modeling of the complete cycle from electrical excitation through piezoelectric transduction, ultrasonic acoustic waves, and finally reverse piezoelectric transduction to generate the received electric signal. Power and energy aspects of this process will be considered and discussed. The presentation will end with conclusions and suggestions for further work.