A tunable hybrid damper with Coulomb friction and electromagnetic shunt damping

Vibration dampers with tunable properties are of practical significance to accommodate the need of vibration control under different circumstances. Among major parameters, tunable damping to deliver required accuracy within a given frequency range is difficult to achieve in practice. This paper proposes a hybrid tunable damper by combining the advantages of both Coulomb friction damping and electromagnetic shunt damping. The tunable friction damper (FD) allows for coarse tuning with a larger tunable range, while the tunable electromagnetic shunt damper (EMSD) functions as a fine tuner with fine precision. The end result is a significantly increased tunable frequency range with high precision. The proposed method allows for simple and low cost adjustment of the damping forces in both dampers. A prototype is fabricated and experimentally tested in a dynamic vibration absorber (DVA) system. The predicted tenability is experimentally verified and H_∞ optimal damping of the DVA is readily achieved by using the proposed hybrid damper.