Aerodynamic and mechanical hierarchical aeroelastic analysis of composite wings

The coupled bending-torsion flutter is here investigated through Carrera Unified Formulation (CUF). The hierarchical capabilities of CUF offer a procedure to obtain refined one-dimensional models that, by going beyond the assumptions of classical theories, accurately describe the kinematics of structures. Aerodynamic loadings have been determined according to Theodorsen theory, from which the steady formulation can be easily obtained. The displacement variables over the cross section (x-z plane) are approximated by x,z polynomials of any order, N. The finite element method is used to solve the governing equations, which are derived in a weak form through the principle of virtual displacements. The equations are written in terms of "fundamental nuclei," which do not vary with the theory order, N. Several wing configurations have been studied, giving great attention to thin-walled box beams made of orthotropic material. The effects of sweep angle and lamination scheme on flutter conditions have been investigated, and the results have been compared with solutions obtained from two-dimensional theories, experimental tests, and aeroelastic analyses carried out with the doublet lattice method (DLM). The unsteady theory, combined with advanced beam theories, represents a computationally cheap tool for preliminary aeroelastic studies of complex wing structures.