Piezoelectric Energy Harvesting with a Nonlinear Energy Sink

Abstract

Energy transfer from one system to another system, or vice versa, is happening constantly in many processes with various forms. Vibration in machines or structures can be considered as a form of energy transfer from a source to a receiver. In general, such vibration is unwanted. Vibration suppression is of importance in order to protect machines or structures. To monitor vibration of a large system such as building or bridge, a network of sensors is used. Supply of power to these sensors is challenging due to various difficulties such as accessibility or cost. Energy harvesting using ambient vibration is motivated to make sensors autonomous. Vibration energy can be converted into electric energy through electromagnetic transduction or piezoelectric effect. This research proposes a method to achieve simultaneous vibration suppression and energy harvesting in the broadband manner. A nonlinear energy sink (NES) is a special vibration absorber that is capable of sinking or localizing vibration energy from a primary system. Unlike a linear or nonlinear vibration absorber, the NES’s spring is essentially nonlinear. In this research, a variant NES is developed to achieve vibration suppression and energy harvesting in a broad frequency band. The developed apparatus consists of a fixed-fixed composite beam acting as the NES spring and two magnets attached at the middle of the beam acting as the NES mass. The composite beam is formed by a thin steel beam and two piezoelectric bimorphs attached at the ends of the steel beam. The piezoelectric bimorphs convert the NES vibration energy into electric one. The system modeling is presented. System identification is conducted to determine the parameter values. The transient behaviours of the system are investigated numerically and experimentally. It has shown that the developed apparatus demonstrates the characteristics similar to those of the NES. The harmonically forced responses of the system are examined. The approximate analytical solutions of the steady-state responses are derived. The Matcont is used to obtain the frequency responses plots for various cases. An experimental study has been conducted. Both the numerical solutions and experimental results show that the developed apparatus is capable of harvesting energy while suppressing vibration in a wide frequency band.