Two-span piezoelectric beam energy harvesting

This paper reports an analytical study of nonlinear vibratory energy harvesting via a two-span piezoelectric beam. The distributed parameter electromechanical model is applied to explore the benefits of nonlinear interaction between buckled beam spans. The Galerkin truncation method and harmonic balance method are applied together to find forced responses of the energy harvesting system. The effects of axial pre-pressure on energy harvesting are also explored. The analytical results are supported by utilizing direct time integration of the equation of motion. The amplitude and voltage output frequency response functions (FRF) of single-span, buckled, and two-span piezoelectric beam configurations reveal some differences. For example, the voltage output FRF of the two-span buckled configuration is larger than that of the other two configurations at high frequencies, whereas at low frequencies, the voltage output FRF of two-span unbuckled configuration is larger than that of the other two configurations. Moreover, two-span buckled configuration has more natural frequencies lying at the concerned frequency range. Finally, a hybrid harvester is proposed, which combines harvested voltage from single-span buckled, two-span, and two-span buckled piezoelectric beam to cover a demand of broadband voltages output.