Ultra-low-frequency piezoelectric energy harvesting via adjustable nonlinear inertance

The traditional piezoelectric energy harvesting device cannot adapt to efficient vibration energy harvesting in various environments. The adjustable piezoelectric device for harvesting energy proposed in this article can change the angle of the rotating gears and thus change the system's natural frequency, which solves the difficulty that the device for harvesting energy cannot adapt to the environment of various vibration frequencies. In this paper, an adjustable gear set and a large mass element are connected to a multi-spring structure, and the system geometrical parameters can be changed by rotating the gear set, and change the system's force displacement features. Two small mass elements are horizontally connected to the large mass element in the center for changing the dynamic mass. The present paper provides a detailed exposition of the dynamic equations of the system, with the harmonic balance method employed for both the presentation and solution of these equations, using Taylor expansion for its nonlinear terms, The amplitude response curves across different frequencies are drawed on the foundation of the following. Plots in multiple colors displaying the root mean square (RMS) values of both the induced voltage and electric power were created by means of the Langer-Kutta way. It is evident that the rotation of the gears has the capacity to modify the nonlinear stiffness of the system includes both flexible and rigid features. Concurrently, the inertial amplifier possesses the ability to alter the system's intrinsic frequency, and the system can collect energy efficiently in different situations. The methods used in this paper rely solely on theoretical analysis and numerical simulation.