A novel vari-potential bistable nonlinear energy sink for improved vibration suppression: Numerical and experimental study

Abstract A novel vari-potential energy bistable nonlinear energy sink (VBNES) is proposed in this paper. By introducing a pair of tuned oscillators (TOs) to dynamically adjust the potential barrier height of the BNES, the excitation threshold of the strong modulated response (SMR) is reduced and its vibration suppression ability is enhanced, especially under ultra-low and wide-amplitude excitation. Firstly, the dimensionless theoretical models of the VBNES and the fixed-potential BNES (FBNES) are constructed by the Lagrange equation. The actual response trajectories on the potential energy surface and restoring force surface are numerically tracked to verify the benefit of variable potential energy effect on vibration suppression. The dynamical characteristics of the typical target energy transfer (TET) mechanisms of the VBNES and their contributions to energy dissipation are analyzed. Furthermore, the transient responses and energy dissipation rates of the VBNES and FBNES with optimal stiffness under impact excitation are compared. The results indicate that the VBNES has higher impact vibration absorption efficiency and stronger robustness. The influences of system parameters on energy dissipation rate are analyzed. Finally, the experimental and numerical studies under harmonic excitation are carried out. The experimental results verify the correctness of the theoretical model. The complex dynamics under numerical frequency and amplitude sweeps demonstrate that the VBNES has a lower excitation threshold of the SMR and a broadband SMR. Parametric studies show that the optimal stiffness depends on the excitation amplitude.