Variable-potential bistable nonlinear energy sink for enhanced vibration suppression and energy harvesting

A variable-potential bistable nonlinear energy sink coupled electromagnetic harvesters (VBNES-EH) is proposed, that can simultaneously achieve high efficiency, broadband vibration suppression and energy harvesting under ultra-low and ultra-wide input energy level excitation. The performance is enhanced by introducing two hori-zontal energy harvesters (HEHs) to dynamically reduce the potential barrier height of the bistable nonlinear energy sink (BNES) or called bistable energy harvester (BEH) to form lower excitation thresholds of the chaotic and strong modulated responses. Firstly, the dimensionless mathematical model of the VBNES-EH is proposed and verified by the experiment. The experimental results are qualitatively consistent with the simulation results. The transient dynamics and the corresponding energy dissipation rates of five target energy transfer (TET) mechanisms for the weakly damped system are summarized numerically. The variable-potential energy effect and its benefits for the dual functions of vibration suppression and energy harvesting are analyzed. Afterward, the stiffness of the VBNES-EH and the fixed-potential BNES-EH (FBNES-EH) are optimized, and their energy dissipation rates under impact excitation are compared. The results indicate that the former has better perfor-mance under low-and intermediate-level impact excitations. Furthermore, the influence of system parameters on the energy harvesting rate is discussed to guide the optimal design of the performance. Finally, the dynamical evolution of the VBNES-EH and the parameter effects on the dual performance of the system under harmonic sweep excitation are investigated. Numerical results demonstrate that the VBNES-EH can achieve high perfor-mance under the different amplitudes of the harmonic excitation through stiffness optimization.