Nonlinear Modal Interactions of Swept Composite Aircraft Wings Carrying External Stores

Modal interactions of swept aircraft wings carrying external stores in the presence of an internal resonance are investigated. The wing structure is modeled as a geometrically nonlinear composite thin-walled beam incorporating transverse shear strain and warping restraint effects. The anisotropy of the constituent material–induced bending-twist elastic coupling and the heavy external store–caused inertial couplings are accounted as well. The governing equations and the associated boundary conditions are derived via Hamiltons principle. The extended Galerkins method is adopted to semidiscretize the wing-store system, and then the nonlinear analysis is implemented based on the method of multiple scales. Based on the derived amplitude modulation equations under the condition of simultaneous internal and external resonances, steady-state solutions and their stability are critically discussed. Energy flow directions during modal interactions are investigated. In addition, conditions for the occurrence of saturation and jump phenomena are discussed.