Performance of embedded piezoelectric sensors in fiber glass epoxy composites.

摘要

Composite structures with integrated sensors are essential in structural health monitoring (SHM) due to their potential for delivering real-time structural evaluation such as the extent and location of damage. The objective of this study was to characterize the performance of embedded piezoelectric PZT (Lead Zirconate Titanate) sensors in terms of their strain transfer capability in comparison to surface mounted PZT sensors in epoxy glass fiber composites. Computational and experimental studies to determine output voltage from a PZT sensor under applied strain have been investigated to characterize the electromechanical coupling for both surface mounted and embedded piezoelectric sensors. Finite element models of composite specimens with surface mounted or embedded PZT sensors under 3-point bending have been developed. Experimental work involved manufacturing epoxy glass fiber composites with embedded PZT sensors and surface mounting PZT sensors. The specimens were subjected to three point bending with increasing loads increments till failure. After each increment, vibration testing at different frequencies near resonance were performed to evaluate the electromechanical coupling coefficient. Results from testing showed that different sensor configurations had negligible effect to elastic modulus and ultimate stress values, but ultimate strain was higher for the surface mounted cases. Although increased bending stress in the composite specimens resulted in a drop in electromechanical coupling, the drop was much smaller in the embedded sensor cases.