Piezoelectric stacked transducer evaluation and comparison for optimized energy harvesting

The primary focus of this research is on the application and optimization of direct piezoelectric effect in energy harvesting from low frequency mechanical vibrations such as from roadway traffic. The specific research aim is to evaluate the various stacked PZT transducers in their mechanisms and performance on effective electromechanical energy conversion. Piezoelectric power output has been determined based on understanding of the fundamental concepts in composites (1: 3 bi-phasic) and stacked transducers. Several property structure relations are evaluated by various experimental methods including the utilization of electrodynamic test systems. Power evaluation is compared among several samples in order to understand the most efficient configuration utilizing PZT ceramics. Power density as function of applied mechanical force and pressure, are calculated and compared with the experimental results which yield good agreement. Three types of stacked PZT transducers were compared and systemically tested for their electromechanical power conversion performance. The 1: 3 composite stacked PZT transducer was found to be the best performer in term of power density per unit active volume, the specially designed and fabricated stacked PZT transducers (UTSA stacked sample) were found to have the highest power density per transducer volume, 0.615mW/mm(3), measured at 965 kN/m(2) (140 PSI), among the three types studied (1: 3 composite stacked sample, assembled stacked sample and the commercially sourced stacked sample). The pressures and forces used were based on the traffic flow monitoring and federal and state regulations.