Application of quasi-zero stiffness structures in low-frequency vibration energy harvesting: design, modeling, and experiment

In response to the demand for structural health monitoring in modern infrastructure, this study proposes a novel ultra-low-frequency piezoelectric-electromagnetic hybrid energy harvester (QZS-PEHEH) optimized for low-frequency and low-amplitude environments. The harvester leverages quasi-zero stiffness (QZS) characteristics, achieved by integrating horizontal and vertical curved beams, to reduce the system's natural frequency and enhance energy harvesting efficiency. A theoretical model and finite element analysis are used to evaluate the static stiffness and validate the QZS properties. Nonlinear dynamic behavior is analyzed through electromechanical coupling equations and the harmonic balance method, quantifying performance under various excitation conditions. Key parameter influences are investigated to guide system optimization. Experimental results demonstrate a maximum output power of 14.28 mW under optimal load conditions, confirming the harvester's efficiency in ultra-low-frequency environments. The QZS-PEHEH offers a promising solution for energy harvesting in structural health monitoring applications, effectively addressing the challenges of low-frequency vibrations.