Quasiperiodic energy pumping in coupled oscillators under periodic forcing

The effect of a nonlinear energy sink (NES) with relatively small mass on the dynamics of a coupled system under periodic forcing in the vicinity of a main (1:1) resonance is studied theoretically and experimentally. It is demonstrated that over a range of amplitudes of the external forcing the damped system exhibits a quasiperiodic vibration regime, rather than the steady-state response reported in earlier publications. This regime is related to attraction of the dynamical flow to a damped-forced nonlinear normal mode (NNM) of the system and hysteretic motion of the flow in the vicinity of this mode. A physical experiment using an appropriate electric circuit confirms the above results. The regime of quasiperiodic response is shown to provide more efficient vibration suppression than the best-tuned linear absorber with the same mass. (c) 2006 Elsevier Ltd. All rights reserved.