Limit cycle oscillation prediction for aeroelastic systems with continuous non-linearities

This paper describes an investigation into the prediction and characterisation of Limit Cycle Oscillations (LCO) occurring in non-linear aeroelastic systems. Through the use of Normal Form Theory, it is shown how it is possible to predict the amplitude of Limit Cycle Oscillations as function of two variables, the air speed and the reduced frequency. The approach is analytical and does away with the need for numerical simulation of the system. The methodology is demonstrated upon a simple two degrees-of-freedom aeroelastic wing model with cubic stiffness. The characteristics of the Limit Cycle Oscillations were determined and compared with those produced via numerical simulation. A good agreement was found for all the cases considered.