Nonlinear analysis of flexoelectric acoustic energy harvesters with Helmholtz resonator

This paper presents a Helmholtz Resonator-type Flexoelectric Acoustic Energy Harvester (HRFAEH), composed of a Helmholtz Resonator (HR) and a double-sided Flexoelectric Disk Oscillator (FDO). The electromechanical governing equations, incorporating geometric nonlinearity, are derived using Hamilton's principle. Utilizing the multiscale method, we obtain the cavity sound pressure, oscillator displacement, and voltage output response, with validation through simulations in COMSOL. The study's innovation lies in the concurrent consideration of piezoelectric and flexoelectric effects, enhancing the system's performance. The inclusion of geometric nonlinearity, accounting for large deformations, enhances the model's accuracy under high sound pressure excitations. Our research unveils performance degradation in the Helmholtz Resonatortype acoustic energy harvester under elevated environmental sound pressure. The combination of nonlinear analysis and structural optimization effectively mitigates this degradation. In comparison to the non-optimized harvester, the maximum voltage output increases by 39.1 %, and expressions for the optimized model parameters are provided. Additionally, we conduct parameter analyses for the HR and the FDO, elucidating the impact and optimal values of parameters such as film coverage radius and load resistance on system performance.