Research on vibration suppression of nonlinear energy sink under dual-frequency excitation

Abstract

Most of modern civil turbofan engines adopt the dual-rotor layout, which introduces the typical dual-frequency excitation into the dynamic models. This work sets a single degree of freedom (SDOF) linear oscillator for the main system, and establishes the dynamic models of that coupled with the SDOF linear dynamic vibration absorber (DVA) and different configurations of nonlinear energy sink (NES). In view of the typical flutter mechanism of wing, the modal frequency of the first-order symmetric twist typical state of wing is introduced into dynamic models. With the wing, low and high characteristic frequency ratio (1:2.67:12.66) for the typical dual-rotor aero-engine in cruise, the fourth-order Runge-Kutta algorithm is employed for analysis. According to the energy criteria for the dynamic vibration absorber optimization, focusing on the effects of the characteristic frequency ratio on the kinetic energy of the primary mass, total system energy etc., numerical simulation results of comparison can indicate that reducing the torsional vibration of wing by NES is feasible, and NES has better vibration suppression effect than the traditional linear DVA with certain set of parameters under the dual-frequency excitation. In addition, the vibration suppression effects of the SDOF, two-DOF serial and parallel NES on the main oscillator system are focused on. Under the condition that the characteristic parameters of the main system and additive total mass of the vibration absorber remain unchanged, results show the two-DOF parallel NES has the best vibration energy suppression effect under dual-frequency excitation.