Parameter Study on Piezoelectric Length to Harvesting Power in Torsional Loads

In this paper, our study on energy harvesting from partially patterned piezoelectric transducers under torsional loads is reported. The transducers consist of a substrate with a partially covered piezoelectric pattern layer that is split into two equally separated parts. Our research focus is the feasibility of energy harvesting from the transducers and the analysis of the pattern length effect by modeling energy harvesting responses from the torsional deformations at various piezoelectric pattern lengths. This model is utilized to investigate harvested power as a function of the piezoelectric pattern length and load resistance at the excited torsional load. The results of the model are validated against experimental results of energy transducers with four different pattern lengths. From the theoretical predictions and experimental results, it is observed that the maximum harvested power of a few centimeters size transducer approaches 100 mW per unit tip twist angle, in radians, at the excitation frequency of 10 Hz. Moreover, it is found that the harvested power from the energy transducers is related to the spatial derivative of the twist angle and the capacitance, which are changeable along with the piezoelectric pattern length. Therefore, for any particular energy harvesting condition, an optimal length exists.