Analysis and Modeling of Intermittent Fluctuation Mechanisms of Piezoelectric Impact-Induced Vibration Cantilever Energy Harvester

Piezoelectric impact-induced vibration cantilever energy harvesters for conventional energy have low ambient vibration frequencies. Expanding the response bandwidth of vibratory energy harvesters and improving their conversion efficiency are crucial. To achieve this goal, researchers have focused on designing the structure. While the structural design of piezoelectric energy harvesters has been extensively studied, further investigation of the impact inputs on power and efficiency remains critical. This study probes the gap change in power with the increase in rotational speed.

A method combining theoretical analysis and simulations was proposed to predict the voltage output of the energy harvester. The physical process of piezoelectric shock-vibrated cantilever beams is theoretically explained and understood, which helps understand the laws of motion, contact behavior and mechanical response of piezoelectric cantilever beams when subjected to shock vibration, thus guiding the construction of the COMSOL model and the interpretation of the results. A finite-element model of the piezoelectric impact-induced cantilever energy harvester was established using COMSOL Multiphysics, and its validity was verified by comparing the simulation and experimental data. The factors discussed include the contact time between theexcitation gear and piezoelectric cantilever beam (hereafter referred to as contact time), external load, overlap length between the excitation gear and piezoelectric cantilever beam (hereafter referred to as overlap length) and the length of the cantilever beam are discussed. The factors affecting contact time, including the natural frequency and rotating speed, are further discussed, and a calculation method for the energy-harvesting efficiency of the proposed harvester is presented.

The findings reveal that the intermittent variation in power with increasing rotating speed was the intermittent variation in the contact time. The simulation results demonstrated that the maximum efficiency was 40.36% when the rotating speed was in range of 200–400 r/min.

The study concludes that significant variations in contact position at different rotational speeds affect the contact time, which leads to intermittent variation in power output. We observed a significant increase in power generation when the contact position was at the crest position. This understanding enhances the comprehension of the dynamic behavior of piezoelectric cantilever beams under varying rotational speeds. The insights gained from this research provide a basis for optimizing the design and efficiency of piezoelectric energy harvesters and suggest new avenues for future research in the field.