Nonlinear Static Aeroelasticity of High Aspect Ratio Wing Aircraft by FEM and Multibody Methods

Two procedures for the nonlinear static aeroelastic analysis of flexible high aspect ratio wing aircraft subject to geometric nonlinearities are developed. The two approaches are based on the nonlinear Finite Element Method and on multibody dynamics, and employ aerodynamic formulations based on Doublet Lattice Method and strip theory respectively. Static aeroelastic results in terms of wing integrated loads at various trim conditions for a very flexible aircraft test case are presented and compared to the linear ones. Significant differences are found between linear and nonlinear approaches and attention is drawn to the importance of the follower force effects of the aerodynamics and of considering large displacements and rotations, identified as the main sources of the discrepancies, for the static flight loads computation and subsequent structural sizing of the wing.