Theoretical modeling and experimental verification of a 3-DOF bistable flutter-based energy harvester

This paper proposes a novel 3-DOF bistable flutter-based energy harvester (TBFEH) that converts wind energy into electrical energy by utilizing flutter-induced plunge motion to excite a piezoelectric cantilever beam. A dimensionless dynamic model of the TBFEH is established based on Euler-Bernoulli beam theory and Lagrange's equations. Wind tunnel experiments show that the TBFEH has a cut-in wind speed of 4.07 m/s, delivering an average power of 73.02 μW and a peak output power of 297.10 μW at 10.46 m/s. Comparative experiments against a monostable harvester verify that TBFEHs with different springs have a broader operating wind speed range. The energy harvesting performance and dynamic evolution of TBFEHs is examined. Numerical analysis reveals two distinct nonlinear response regimes in the TBFEH with a soft spring: chaotic motion at low wind speeds, where a great number of transitions between intrawell and interwell vibration improve performance, and quasi-periodic motion at high wind speeds preceding a high-amplitude vibration regime promote the energy harvesting efficiency. Parametric studies further identify optimal design parameters for performance enhancement.