Aeroelastic analysis of the high aspect ratio wing considering the geometric nonlinearity

The large deformation of high aspect ratio wing during flight has an important effect on the aeroelastic stability of an air-vehicle. The aerodynamic performance and flying safety of high-altitude, long-endurance uninhabited air vehicles are greatly affected. Therefore, the geometric nonlinearity of high aspect ratio wing can't be ignored. Based on the secondary development of MSC.Nastran software, the method to analyze the aeroelastic characteristics considering the geometric nonlinearity was proposed. Considering the effect of large geometric deformation on aerodynamic surface grid, the aerodynamic surface grid was updated at every iterative step, the static aeroelastic deformation at the flight condition was obtained with a convergent iteration, then the flutter characteristic of the large aspect ratio wing was analyzed based on the stiffness matrix considering the geometric nonlinearity. Using the method, the aeroelastic characteristic of the large aspect ratio wing model was analyzed. It is shown that comparing with the linear result, the dynamic aeroelastic characteristic is affected by the static aeroelastic deformation, the torsion frequency of the wing decreases and the coupled bending-torsional flutter velocity drops at the same time.