AEROELASTIC ANALYSIS OF A FLEXIBLE CONTROL SURFACE WITH STRUCTURAL NONLINEARITY

Abstract

This article is concerned with a time domain approach to the nutter analysis of a night vehicle control surface with concentrated nonlinearities, In this study, an elastic model of a control surface with root freeplay nonlinearity in pitch is considered. A finite element structural model is used for structural analysis and a doublet lattice unsteady aerodynamic model is used for the calculation of aerodynamic loads, In approximating the frequency domain aerodynamic forces, the least-square rational function approximating method is used with an optimizing algorithm, To transform the frequency domain aerodynamic forces to the time domain forces, the method of Brace and Eversman is used. To reduce the problem size and the computation time, the fictitious mass modal approach is used, which can afford the possible local change of structural properties, The effects of the initial conditions and the magnitude of nonlinearity on the aeroelastic characteristics are examined. The aeroelastic responses are sensitive to initial conditions, Limit cycle oscillation and chaotic motion are observed in this study. The presence of freeplay makes the divergent nutter speeds larger than those of a linear case.