Effect of changing the coefficient of restitution of a single-sided vibro-impact nonlinear energy sink in a two-story structure

In many applications of structural dynamics, it is desirable to transfer energy from a primary system using a dynamic absorber to protect the structure from destructive vibration amplitudes. Nonlinear Energy Sinks (NESs) are local attachments used to rapidly and passively dissipate energy from a primary structure in a phenomenon known as Targeted Energy Transfer (TET). Consequently, many types of NESs, which incorporate an essential nonlinear property, have been proposed, designed and tested in the literature. Based on numerical and experimental investigations of these types, Single-Sided Vibro-Impact (SSVI) NESs, where impacts, usually between the top floor of the primary structure and the NES, are utilized to further dissipate energy, proved to be the most efficient for TET in small- and large-scale structures. In literature, researchers have mostly considered steel-to-steel impacts which correspond to a coefficient of restitution of approximately 0.7. In this work, the effect of changing this coefficient of restitution is analyzed and investigated in a two-story physical primary structure. The coupled systems are optimized to achieve the maximum energy transfer and dissipation by measuring the normalized weighted-averaged effective modal damping criteria. It is found that lowering the coefficient of restitution increases the capability of the SSVI NES to transfer and dissipate initial energy induced into a primary structure for a wide range of impulsive excitations.