The dynamic aeroelastic capabilities in the automated structural optimization system were used to evaluate the flutter behavior of various fully built-up finite element wing models in subsonic and supersonic flow. First, the performance of the flutter module was tested against results from other codes. Then, models of various wings with different aspect ratios were investigated for the influence on the free vibration and flutter characteristics of such modeling factors as finite element selection, structural grid refinement, number of selected modes, retention of in-plane and breathing modes, aerodynamic panel size and placement, splining of the aerodynamic grid to the structural grid, selection of extra points off the structural wing box for splining, solution procedures such as eigenvalue extraction routines, reduction schemes, etc. The results suggest that a quick initial evaluation of a preliminary wing design with a reasonably coarse grid for both the structure and the aerodynamics will result in natural frequencies and modes that are close to those from a more detailed model and in flutter speeds that tend to be conservative. Overall, such a simple model can represent a good start for a conventional redesign process as well as for optimization.
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