Ricerc@Sapienza

A nonlinear energy sink (NES), conceived to mitigate the vibrations of a multi-degree-of-freedom host mechanical system, is considered. The high-dimensional slow invariant manifold (SIM) describing the high-amplitude slow dynamics of the system is derived and exploited to interpret its transient regimes caused by impulsive excitation. It is shown that algebraic expressions derived from the SIM formulation enable to identify the so-called interaction points, providing the conditions in which two modes of the primary system interact and share energy through the nonlinear absorber.

The present paper deals with the dynamics of a two-degrees-of freedom system consisting of a nonlinear absorber attached to a primary linear structure under external excitations. The nonlinear attachment exhibits a hysteretic restoring force modeled with the classic Bouc–Wen law [hysteretic vibration absorber (HVA)]; furthermore, the mechanical characteristics of the nonlinear oscillator are tuned to regulate the ratio between the two natural frequencies and to lead the system near to internal resonance conditions.