Design and dynamic analysis of an ultra-low frequency bistable vibration energy harvester with quasi-zero stiffness

Abstract In order to effectively harvest vibrational energy in ultra-low-frequency environmental excitations, a quasi-zero-stiffness bistable vibration energy harvester (QZS-BVEH) is presented in this paper. The design of the QZS structure allows the oscillator to easily overcome the potential energy barriers between equilibrium points when subjected to weak disturbances, resulting in significant displacement or snap-through motion. Consequently, a tri-magnet configuration is employed, incorporating a relative magnet pole arrangement, to ameliorate the adverse stiffness impact of the bistable structure, thereby diminishing the potential energy barriers. Firstly, the geometric, stiffness, and magnetic parameters required to achieve quasi-zero stiffness in the structure are determined through statics and energy analysis. Subsequently, dynamics analysis of the harvester reveal phenomena such as intra-well oscillation, cross-well chaos and multi-period motion within the frequency range of 0.3 Hz to 4 Hz, all of which are the key to improve energy outputting in the ultra-low frequency. Finally, experimental voltage signal and numerical results are compared to validate the correctness of the dynamics model. Therefore, this design approach for the energy harvester can enhance the device sensitivity to ultra-low-frequency vibrations in the environment, offering potential application value for vibration energy harvesting in ultra-low-frequency environments.