A preliminary study on nonlinear dynamics in vortex-induced vibration systems

Abstract

This study investigates the dynamics of a vortex-induced vibration energy harvester (VIVEH), utilizing a piezoelectric patch attached to a beam with nonlinear stiffness introduced through magnetic coupling. The research evaluates the system's response under varying wind speeds and initial conditions, focusing on small and large displacement regimes. A modified Van der Pol oscillator models the vortex shedding forces, coupled with a nonlinear restoring force, and the system equations are numerically solved using a fourth-order Runge-Kutta integrator. Results reveal that nonlinear stiffness significantly influences the lock-in region and energy generation. For "hard" stiffness configurations, large-amplitude oscillations expand the lock-in region and enhance energy output, while "soft" stiffness leads to reduced amplitudes and narrower operational ranges. To analyze system dynamics, Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) tools were employed, providing detailed insights into frequency-domain behaviors and time-frequency characteristics. These analyses revealed harmonic interactions that highlight the nonlinear nature of the system's response presenting the potential of nonlinear dynamics in optimizing VIVEH performance for sustainable energy harvesting applications, particularly in increasing the operational bandwidth of wind speeds.