A Piezoelectric Energy Harvester with Bending–Torsion Vibration in Low-Speed Water

This paper presents a piezoelectric energy harvester using an eccentric cylinder undergoing bending–torsion vibration in low-speed water. It can harvest energy from water using vortex-induced vibration (VIV). A distributed parameter beam model with respect to the motion of the piezoelectric beam was established based on Euler–Bernoulli beam theory. The governing coupled equations of the harvester system were derived by Lagrange’s equations. The optimal configurations and work conditions of harvesters were numerically analyzed according to the above mathematical models. Experiments were designed and performed to verify the numerical results. The numerical results were in good agreement with the experiment results, which verifies the validity of the mathematical models. The harvester with bending–torsion vibration generated an output power of 0.3978 mW, which is 1.99 times of that of the harvester with a solid-cylinder tip undergoing bending only.