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Effects of temperature variations on piezoelectric sensor diagnostics process based on impedance measurements (presentation video)

A sensor diagnostic and validation process that performs in-situ monitoring of the operational status of piezoelectric (PZT) active-sensors in structural health monitoring (SHM) applications is presented. The basis of this process is to track the changes in the capacitive value of piezoelectric materials, which shows up in measured admittance. Both degradation of the mechanical/electrical properties of a PZT transducer and the bonding defects between a PZT patch and a host structure could be identified by the proposed process. Due to the temperature dependent nature of piezoelectric materials, we investigated the effects of temperature on sensor diagnostic process. The effect of temperature found to be remarkable, modifying the measured capacitive values significantly. This results indicates that there is need for developing a rigorous signal processing technique to normalizing the temperature effects. It has been also found that, as the temperature changes, the sensor diagnostic process was influenced not only by a sensor and a structure, but by a bonding materials that was used for attaching a piezoelectric transducers to a structure, which would be an important characteristic when designing an SHM system. This paper summarizes considerations needed to develop such sensor diagnostic processes, experimental procedures and results, and additional issues that can be used as guidelines for future investigations.