A miniaturized electromechanical Impedance-based Node for the wireless Interrogation of Structural Health

摘要

This paper presents the development and applications of a miniaturized impedance sensor node for structural health monitoring. The principle behind the impedance-based structural health monitoring technique is to apply high frequency structural excitations (typically higher than 30 kHz) through the surface-bonded piezoelectric transducers, and measure the impedance of structures by monitoring the current and voltage applied to the piezoelectric transducers. Changes in impedance indicate changes in the structure, which in turn can indicate that damage has occurred. Although many proof-of-concept experiments have been performed using the impedance methods, the impedance-measuring device is bulky and impractical for field-use. Therefore, a recently developed, miniaturized, low-cost impedance measurement chip was used to measure and record the electric impedance of a piezoelectric transducer. The performance of this miniaturized and portable device has been compared to our previous results and its effectiveness has been demonstrated in detecting bolt preload changes in a bolted frame structure. Furthermore, the possibility of wireless communication and local signal processing at the sensor node has been investigated by integrating the device with a microprocessor and telemetry.