Targeted Energy Transfer Between a Swept Wing and Winglet-Housed Nonlinear Energy Sink

Abstract

A prototype nonlinear energy sink, whose design is based upon parameters determined to effectively suppress transonic aeroelastic instabilities of a wind-tunnel wing model (denoted as generic transport wing) via passive targeted energy transfer, is introduced. The lightweight nonlinear energy sink is mounted within a low-profile winglet, which is attached to the tip of the generic transport wing. In addition, safety features and measurement hardware have been built in to the prototype to facilitate a future transonic wind-tunnel experiment. The effects of the nonlinear energy sink on the structural dynamics of the model wing are demonstrated in ground vibration tests, both experimental and computational. Results show that the nonlinear energy sink causes a significant increase in the dissipation rate of energy in the second bending mode of the generic transport wing, even for small wing-tip oscillations. This is a strong indication that the prototype nonlinear energy sink will be effective in wind-tunnel tests because the frequency of the second bending mode is within the range of experimental and computational flutter frequencies of the generic transport wing. Furthermore, accompanying computational analysis is used to show that moderate friction damping in the nonlinear energy sink is unlikely to have a significant effect on the qualitative interaction between the nonlinear energy sink and the generic transport wing.