Fluid sloshing augmented parametric excitation for enhanced piezoelectric vibration energy harvesting

This study presents a comprehensive experimental investigation of a piezoelectric vibration energy harvester employing a cantilever bimorph beam integrated with a cylindrical container partially filled with water. The system is subjected to vertical base excitation designed to induce principal parametric resonance, while simultaneously exploiting fluid sloshing dynamics as a means of enhancing energy harvesting performance. The objective is to examine the synergistic effects of parametric excitation and nonlinear fluid–structure interaction on the energy harvesting efficiency and bandwidth of the device. The presence of liquid in the tank introduces dynamic sloshing phenomena, characterized by multiple sloshing modes, which couple with the beam’s transverse motion. Through systematic variation of excitation frequency and liquid depth, the experiment evaluates their influence on the voltage output, and electrical power across different resistive loads. Results demonstrate that the combination of principal parametric excitation, where the base excitation frequency is tuned close to twice the system’s fundamental frequency, and sloshing-induced modal coupling can significantly enhance the harvester’s bandwidth. Increasing the liquid depth effectively reduces the system’s first natural frequency due to the added inertia and liquid mobility, thereby shifting the parametric resonance zone toward lower frequencies. Additionally, the water depth-to-container diameter ratio serves as a tunable geometric parameter that allows control over the operational bandwidth. 58% increase in the effective energy harvesting bandwidth is recorded at higher liquid depths, without the need for increasing the system’s physical size.