Abstract:Nonlinear energy sink (NES) absorber has a critical feature of mitigating vibrations in broad frequency ranges, which could be utilized in vibration reduction of tall structures. In this paper, partial differential equations governing system motion are concluded, whereby the analytic expressions of nonlinear normal modes are achieved by applying Galerkin’s method and Rauscher’s method. The analysis on the nonlinear normal modes reveals the vibration suppression principle of the NES absorber. Time history analysis is conducted for parametric analysis of the vibration suppression of NES-Structure system, through nonlinear finite-element-method (FEM). Results indicate that the NES absorber has optimal parameters, with those the structure vibration would be greatly suppressed, namely the structure vibrates on a level of 20% of the vibrating structure without NES. The empirical formula proposed is capable of predicting the optimal cubic stiffness values of NES absorber, and the values agree well with those obtained via FEM.