Optimal Flutter Suppression of Nonlinear Typical Wing Section Using Time-Domain Finite Elements Method

Abstract

In this paper, the optimal time-domain finite element method is applied to the flutter suppression of a nonlinear two-dimensional typical wing section. The aeroelastic governing equations are based on the inclusion of stiffness nonlinearity in pitching motion and on the quasi-steady aerodynamics. The flutter suppression problem is formulated as a general optimization problem with equality constraints that are functions of state variables. Using the variational approach, the optimality conditions are derived and the resulting equations are discretized in time-domain. Then, by setting out the discrete equations, a set of nonlinear algebraic equations is generated, and through the Newton–Raphson method, the optimum answer is attained. The numerical results are presented in which the performance of the nonlinear optimal control system designed by the time-domain finite element technique for nonlinear aeroelastic wing sections is illustrated.