Assessment of geometrically nonlinear effects on the aeroelastic response of a transport aircraft configuration

This paper investigates geometrically-nonlinear aeroelastic effects on an industry-level aircraft configuration. Results are obtained via a new approach that uses geometrical information to compute nonlinear effects and seamlessly integrates with conventional, linear aeroelastic load packages. The starting point is a generic finite-element model and frequency-domain aerodynamic influence coefficient matrices, and the resulting system includes control inputs, longitudinal trim, or gust disturbances in time domain, which can be employed separately or in combination to obtain a nonlinear dynamic model for loads and stability analysis. The aeroelastic response of a long range aircraft is studied, highlighting the difference between linear and nonlinear approaches in the calculations of the aircraft flying equilibrium, dynamic perturbations, and variations to the flutter boundary. Results justify the need for geometrically nonlinear analysis in the production environment of airplanes with ultra high aspect ratio wings