Physics-Based Identification and Management of Aeroelastic Limit-Cycle Oscillations (LCO)

A highly qualified team consisting of NextGen Aeronautics Inc., the University of Illinois, Texas A&M University and NES Tech, Inc., proposes an approach to the problem of aircraft limit cycle oscillations (LCO) that includes both analytical predictive methods and hardware for preventing in-flight LCO. LCO phenomena to be addressed include those induced by structural nonlinearities, shock-boundary layer interaction, free-play, and transonic flow effects. The team will leverage considerable prior work by its members, including development of an innovative nonlinear energy sink (NES), variations of which have been designed, built and wind-tunnel-tested with very successful results. The approach will allow for the recognition and suppression of transient, nonlinear modal interactions that trigger LCO events. This is in contrast with standard practice of treating the actual LCO event subsequent to its buildup, by either passive or active techniques. The proposed NES hardware is lightweight and possesses unique nonlinear dynamical features that enable it to passively draw and locally dissipate broadband vibration energy from the aircraft structure, leading to rapid and robust suppression of LCO instabilities. Moreover, the NES can interact with structural modes in arbitrary frequency ranges acting, in essence, as a passive adaptive boundary controller.