Targeted Energy Transfer Between a Model Flexible Wing and Nonlinear Energy Sink

Abstract

Passive and nonlinear targeted energy transfers induced by resonant interactions between a single-degree-of-freedom nonlinear energy sink and a flexible swept wing are studied. With a series of ground-vibration tests, it is shown that the nonlinear energy sink can be designed to quickly and efficiently absorb energy from one or more wing modes in a completely passive manner. Results indicate that it is feasible to use such a device to suppress or prevent aeroelastic instabilities like limit-cycle oscillations. The design of a compact nonlinear energy sink is introduced and the parameters of the device are examined experimentally, confirming that the required nonlinearizable stiffness is achieved. Ground-vibration experiments performed on the wing's nonlinear energy-sink system indicate that targeted energy transfer is achievable, resulting in a significant reduction in the second bending mode response of the wing. Furthermore, a finite element model of the system is developed to computationally reproduce the experiments, providing good agreement between the two. Finally, the finite element model is used to simulate the effects of increased nonlinear energy-sink stiffness on the system and to show the conditions under which the nonlinear energy sink will resonantly interact with higher-frequency wing modes.