Nonlinear aeroelastic analysis of an airfoil with control surface free-play using stochastic approach

In this study the nonlinear aeroelastic of an airfoil with control surface free-play nonlinearity was analyzed using a stochastic approach. An unsteady aerodynamic flow based on the Theodorsen function was applied to model the aerodynamic load and moments. Using the stochastic approach, response variance against flow speed was analyzed where the flow speed of the maximum variance was taken as flutter speed. The results show that the effect of free-play nonlinearity on the decrement of the flutter speed is considerable if the flutter of the corresponding linear system is due to the flap motion instability. Moreover, the response variance of the nonlinear system experienced the flip bifurcation and chaos before the linear flutter speed and left the chaos through an intermittency road and tangent bifurcation. This tangent bifurcation led to jump phenomenon and abrupt change in response variance and was thus regarded as the nonlinear flutter speed. Tackling the challenge of aeroelastic analysis with free-play nonlinearity based on the stochastic approach is novel. We demonstrate that this approach is an efficient method which provides a better vision of types of bifurcation, chaos and jump phenomenon. (C) 2017 Elsevier Ltd. All rights reserved.