Use of a Piezocomposite Generating Element in Energy Harvesting

In this work, we propose a high performance piezocomposite generating element (PCGE), which can be used in energy harvesting applications and evaluate its electricity generating performance. The effectiveness of the PCGE is verified with numerical and experimental data. The PCGE is composed of layers of carbon/epoxy, piezoelectric lead zirconate titanate (PZT) ceramic, and glass/epoxy cured at an elevated temperature. The results of this study reveal that the output voltage of the PCGE under vibration is affected considerably by variations in the layup configurations of the PCGEs and residual stress after the curing process. In particular, each laminated structure has a distinctive moment arm and bending stiffness, both of which affect the generating performance of the PCGE. Besides the effect of the layup configuration, the curing process causes the PCGE to have residual stress in the PZT layer because of a mismatch in the coefficients of thermal expansion between the constituent layers. This residual stress generally causes a change in the voltage coefficient, g(31), of the PZT layer. The ANSYS (TM) program was used to conduct a finite element analysis of the stress distribution in the PCGE. For the experimental tests, three kinds of PCGE layup configuration are subjected to vibration in order to validate theoretical predictions and verify the PCGEs' capability of converting oscillatory mechanical energy into electrical energy. The experimental results confirm that the electricity generating performance can be enhanced by a proper design of the PCGE.