Earlier work did not find any static stiffness nonlinearities in the F-16 wing structure, but suggested that dynamic nonlinearities may be present. Computational studies have demonstrated that small amounts of nonlinear structural damping are sufficient to change a diverging flutter oscillation into a limited amplitude oscillation. Experimental damping measurements of a fixture-mounted F-16 wing were made to determine whether damping nonlinearities are significant and to quantify the nature of any structural damping present in the built-up wing structure. Three fundamental component configurations of the wing were examined: wing box only, wing (i.e., wing box with leading- and trailing-edge control surfaces), and wing with wingtip launcher. A ground vibration test approach was used with a stepped-sine excitation technique over a range of excitation forces. Damping and frequency were extracted from measured frequency response functions of the stepped-sine test data using a modified single degree-of-freedom modal analysis technique. Nonlinear damping with respect to bending mode displacement was observed for all test configurations. The overall magnitude of the damping increased when control surfaces were installed on the wing box. The presence of a wingtip launcher decreased the damping at higher displacements.
Experimental Characterization of Nonlinear Damping in the F-16 Wing Structure
Journal of Aircraft ; 58 , 2 ; 236-243
2020-08-13
8 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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