Abstract: Geometrically nonlinear aeroelastic problems are key issues in the design of large flexible aircrafts, and accurate model-ing of large deformation structures is the basis for geometrically nonlinear aeroelastic analysis. Compared with the non-linear finite element method, the reduced order model has the advantages of low order and fast solution, but the traditional structural modal modeling method is not applicable to nonlinear structures. For a large flexible aircraft wing, a nonlinear structural reduced-order model is established with the linear structural modes as the base, and the nonlinear stiffness coefficients are solved in a "non-intrusive" way, and the residual basis functions are supplemented to improve the accu-racy of structural de-formation calculation, and the results are in good agreement with the nonlinear finite element method. The geometrically nonlinear aeroelastic analysis framework is established by combining the non-planar vortex lattice method, and the geometrically nonlinear static aeroelastic deformation, flutter and gust response are analyzed. The re-sults show that the geometric nonlinear factors have an important influence on the design of large flexible wings, and the aeroelastic analysis method based on the nonlinear structural reduced-order model can take into account the analysis accuracy, computational efficiency, and applicability of complex models.

Key words: geometric nonlinear, reduced-order model, aeroelasticity, nonlinear flutter, large flexible aircrafts