Nonlinear dynamical and harvesting characteristics of bistable energy harvester under hybrid base vibration and galloping

To harvest wind energy and vibration energy simultaneously, the nonlinear dynamical and harvesting characteristics of a bistable piezoelectric energy harvester (BPEH) under hybrid excitations are studied in this manuscript. A distributed model of BPEH is established by the generalized Hamilton's principle, Kirchhoff's law, and the quasi-steady hypothesis. The influences of wind speed, base excitation level, magnetic distance and resistance are studied by the harmonic balance method (HBM). The results show that the structure can be optimized to reach the best harvesting performance for wind energy and vibration energy. The analytical prediction and simulation results are verified by the experiments. The coexisting solutions appear while the BPEH is under a hybrid excitation of wind galloping and base vibration. The dynamical response will approach different branches for different initial conditions, by which the system can be intentionally designed to attain the high energy orbit. The experimental results show that the BPEH could reach the highest output efficiency while it undergoes the motion of inter-well period-1. Thus, a high energy output can be realized by controlling the initial conditions to the desired range. This study could provide a comprehensive insight into the promotion of harvesting performance for hybrid ambient excitations.