Suppression Optimization of Vortex-Induced Vibration of a Circular Cylinder based on Nonlinear Energy Sinks

In this paper, the suppression of vortex-induced vibration (VIV) of a cylinder by a nonlinear energy sink (NES) with optimized parameters is investigated. The NES system integrates the auxiliary mass, linear damping, and nonlinear stiffness components and uses the van der Pol wake oscillator to simulate the dynamic characteristics of vortex shedding. The main research contents are as follows: (1) The dynamic equation of the fluid–cylinder–NES coupling system is derived, and the influence of NES parameters on the vibration suppression performance is studied. The slow flow equation is established by using the complexification-averaging (CXA) method. (2) The saddle-node (SN) bifurcation boundary and Hopf bifurcation boundary are derived. The influence of NES parameters on the bifurcation boundary and the influence of bifurcation on the vibration response arestudied. (3) The multiple scales method is used to analyze the slow invariant manifold (SIM), and the necessary conditions for the strongly modulated response (SMR) are derived based on SIM. (4) Aiming to maximize vibration suppression efficiency, a genetic algorithm optimization scheme based on the SMR existence criterion constraint is developed. The results show that the optimization method not only reduces the vibration amplitude of the cylinder by 71.94% but also achieves a continuous SMR response in the ‘lock-in’ interval, which effectively promotes the energy transfer from the cylinder to the NES and improves the energy dissipation efficiency of the system.