Enhancing galloping-based energy harvesting through expanded quasi-zero-stiffness region

Abstract In recent years, quasi-zero-stiffness (QZS) structures have been utilized in designing galloping piezoelectric energy harvesters (GPEHs) to produce large vibration responses and high output power. However, the QZS region is relatively narrow, leading to limited enhancement of QZS-GPEH at large displacement responses. To address this issue, this paper proposes a flat potential-well tuning method to design an improved QZS-GPEH (IQZS-GPEH) by significantly expanding the QZS region. First, the governing equations of the proposed IQZS-GPEH were derived, and a static analysis was conducted to compare the QZS region of the IQZS-GPEH with that of a conventional QZS-GPEH. The results reveal that the QZS property can be extended to accommodate large displacement responses, remarkably expanding the QZS region. Subsequently, the harmonic balance method was applied to derive approximate analytical solutions, and numerical simulations were performed to verify and study the dynamics and power performance of the GPEHs. Finally, wind tunnel experiments were conducted to validate the theoretical and numerical findings. The results show that the proposed method effectively enlarges the QZS region, substantially increasing dynamic responses and voltage outputs. Specifically, as the wind speed increased from 3.6 m s −1 to 5.0 m s −1 , the power output improvement rose from 23.55% to 55.64%. Therefore, it can be concluded that broadening the QZS region is an effective approach to enhancing the performance of QZS-based galloping energy harvesters.