Flutter Boundary Prediction of Digitalized Smart Multimode Systems Using Steady-State Responses

Abstract

Flight flutter test of a newly built airplane is traditionally carried out by measuring the damping of the critical wing mode. As it is hard to evaluate damping coefficients precisely from damped oscillations of the wing, accurate prediction of the flutter speed is very difficult. Since 1980's, the flutter boundary prediction based on digital data techniques has been developed by the present author and his coworkers, focusing on the stability of wing systems by using Jury's stability criterion. Their studies showed that this prediction method was more effective than the conventional damping approach. As the most previous studies were limited to binary-mode systems, here we formulate a smart multi-mode flutter system excited stationary by air turbulence in the flow. Calculating response signals of the system, we perform a simulation analysis of the flutter boundary estimation using Jury’s criterion. Numerical results show that our digitized method based on the Jury criterion is also effective in predicting flutter onset of the multimode system in which at least one higher mode is involved in the occurrence of flutter.