Base-vibrated Parabolically Tapered Piezoelectric Vibration Energy Harvester: Electromechanical Modelling and Experimental Validation

This paper presents a parabolically tapered piezoelectric vibration energy harvester which aims to replace conventionally used batteries in low-power microelectronics and sensor applications. The presented design minimizes the sporadic stress distribution, common in the piezoelectric energy harvesters. The nonlinear behavior, obvious in highly excited piezoelectric systems, is considered in the electromechanical coupled analytical model. The frequency and voltage responses under base excitation levels of 1g, 2g, and 4g are analyzed to estimate the nonlinearities and excitation sensitivity. A thorough parametric analysis is conducted using an L16 array, which incorporates variations in taper parameter, length, substrate thickness, and tip mass. Voltage-per-mass (VPM) and combined performance index (CPI), are the two indices introduced to judge the design efficiency and material utilization. Finite element (FE) simulation and experimental results show a maximum deviation of 3.2% from analytical results, which validates the mathematical model. An experimental prototype, fabricated using the optimized design parameters indicated a VPM of 3.1432 V/gm. A comparative study positioned the proposed design competitively among the existing vibration energy harvesting models. The combined analytical, numerical, optimization, and experimental investigation demonstrates the potential of geometric tailoring for improving the voltage and mass-normalized performance of piezoelectric vibration energy harvesters.