Structural optimization and broadband energy harvesting characteristics of variable-section multimodal piezoelectric energy harvesters

Abstract To address the narrow working bandwidth issue of traditional cantilever piezoelectric energy harvesters, this study proposes a variable-section multimodal circular array piezoelectric energy harvester structure. By theoretically deriving the strain expressions of rectangular, trapezoidal, and parabolic piezoelectric cantilevers, establishing the electromechanical coupling state equation using MATLAB, and combining COMSOL for finite element simulation, the effects of geometric parameters and external excitation on energy harvesting characteristics are analyzed. A test system is built to compare the output performance of different cross-section vibrators in single and array modes. The results show that the variable-section design can effectively adjust the natural frequency, and the circular array achieves multimodal coupling, expanding the working bandwidth to 7–12 Hz and increasing the output power compared with a single vibrator. The high consistency between experiments and simulations verifies the correctness of the model, providing a theoretical basis for the design of broadband piezoelectric energy harvesters.