Surface-mounted smart PZT sensors for monitoring damage using EMI-based multi-sensing technique.

For effective structural health monitoring (SHM), the electro-mechanical impedance (EMI) technique is usually implemented in which smart material, namely, Lead Zirconate Titanate (PZT), is used to observe the possible changes made in the structural performance. The dual nature of PZT has enabled it to work as an actuator as well as a sensor. In this article, the proposal of the multi-sensing technique on the surface-mounted PZT sensors is offered. The investigation is performed on the concrete structures for detecting and localizing the structural damage. Multiple smart sensing units (SSU) are adhesively bonded on the top surface of the simply supported concrete beam. As each PZT sensor has a small zone of influence, therefore, the use of multiple smart sensors is recommended for effective damage detection. As the EMI measurement, the conductance signatures are obtained at different stages in the frequency range of 0-450 kHz. To quantify the changes in the conductance signatures, various damage indices, i.e., root mean square deviation (RMSD) and correlation coefficient (CC), are used. This article also presents the effective methodology for damage localization, which assumes the parallel connection of SSUs under MISO mode. The approximate position of the damage is estimated using the dynamic metrics based upon the multiplexed signatures. The methodology adopted for structural damage detection is effective, as it is verified with the experimental results performed on the concrete structures with multiple surface-mounted PZT sensors. A good agreement is observed in the trend of the numerical results and experimental results, which promotes the implementation of the present methodology for damage detection.