RESEARCH ON THE VIBRATION SUPPRESSION PERFORMANCE OF A SERIES TWO DEGREE OF FREEDOM NONLINEAR ENERGY SINK UNDER PULSE EXCITATION WITH DAMPING NONLINEARITY

Nonlinear energy sink (NES) is a passive energy absorption device that is superior to linear vibration absorbers and plays a crucial role in suppressing vibration in various fields. This paper presents a study on the series two degree of freedom nonlinear energy sink (2-DOF LNES) with linear damping. The vibration suppression performance and energy transfer form of the series two degree of freedom nonlinear energy sink (2-DOF NNES) with nonlinear cubic damping and the combination series two degree of freedom nonlinear energy sink (2-DOF CNES) with linear and nonlinear damping under impact load were studied. The theoretical models of the three systems were described, and the approximate solutions of the corresponding systems were derived using the complex variable averaging method. The corresponding slowly varying dynamic flow equation was obtained. The fourth order Runge-Kutta numerical method was used to longitudinally compare the vibration reduction efficiency and energy transfer form of NES for the same system at different initial energies. Additionally, a transverse comparative study was conducted on the vibration reduction performance and energy transfer form of different systems at the same initial energy. Results showed that the vibration suppression of the NES oscillator on the main structure is mainly achieved through 1:1:1 transient resonance capture. 2-DOF LNES has good vibration suppression ability on the main structure under small initial energy conditions. The 2-DOF LNES and 2-DOF NNES have better vibration suppression capabilities for the primary structure under smaller and larger initial energy conditions, respectively. 2-DOF CNES combines the advantages of the 2-DOF LNES and 2-DOF NNES systems, which not only has a small energy triggering threshold, but also maintains a higher vibration suppression performance when the primary structure is subjected to a larger initial pulse excitation. This advantage makes the system more efficient and robust when dealing with different initial energy conditions.