AN OPTIMUM DESIGN OF NONLINEAR ENERGY SINK VIBRATION ABSORBING DEVICE FOR SUPPRESSING VORTEX-INDUCED VIBRATION OF CYLINDRICAL STRUCTURES

To suppress the vortex-induced vibration (VIV) of a cylindrical structure, an optimal design simulation model of a nonlinear energy sink (NES) vibration-absorber is established based on Van der Pol wake oscillator model, structural dynamics and optimization algorithm. The Van der Pol wake oscillator model and the structural dynamic equation of a two-dimensional elastically supported cylinder are used to establish the model, which predicts one-degree-of-freedom VIV of a two-dimensional elastically supported cylinder. And the accuracy of the model is verified by comparing it with the reference’s experimental data. The nonlinear governing equations of motion with NES are embedded in the above model to modify the VIV model under the action of NES. Combining with an optimization algorithm which changes the parameters of the initial NES, nonlinear energy sink meeting design requirements are achieved. The effect and mechanism of the optimized NES parameters on suppression of the VIV are analyzed by a mount of simulations. The results of optimization case show that the amplitude of the cylinder under NES decreases by 66.39%, when U_\rmr = 5.5. The effect of vibration reduction is obvious. At the same time, the structure parameters of NES obtained by this optimization method meet requirements of actual production and ensure the possibility of physical production design.