Vibrations of a High-Aspect-Ratio, Multi-Element Wing

A full-scale finite element model of a high aspect ratio, back swept, slotted-natural-laminar-flow wing is used to: 1) study the uncoupled and coupled modes of the two elements of the wing; 2) investigate the effects of connection stiffness and number of connections on the coupled modes. The two elements are attached via constraint equations and springs or connectors, using a component mode synthesis approach. The wing model includes the aerodynamic skins as well as internal structural elements. The analysis shows that increasing the stiffness of the springs can couple the two wings such that the low order modes resemble those of a conventional wing. Out-of-plane modes are the most compliant modes with coupling. Torsional modes become mixed bending/torsional modes, with the aft element undergoing most of the deformation. In-plane bending modes appear to evolve to mixed in-plane /out-of-plane/ torsion modes with more connectors or higher stiffness.