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.

A comparative study between a tuned mass damper (TMD) and a nonlinear energy sink (NES), attached to a linear two-degree-of-freedom (DoF) mechanical system under impulsive excitation, is performed. The analysis involves different scenarios; namely, we consider the cases in which only one or both modes of the primary system are initially excited. First, exploiting a harmonic balance approach, the invariant manifolds describing the slow dynamics of the system are identified.