The optimization of a single column subject to a follower load is studied. The shape of the column that maximizes the critical load for a given amount of material is found using optimization. The objective function is nonsmooth and there are also multiple local optima. Improved solutions to the optimization problem are found and compared to previous columns suggested in the literature. The sensitivity to perturbations in shape and refined discretizatiou is also investigated.
A simple and efficient algorithm for robust flutter analysis is presented. First, a general linear fractional transformation formulation of the -k method is provided, making it straightforward to pose the uncertain flutter equation in a form suitable for structured singular value analysis. The new formulation establishes a close connection between -k flutter analysis and traditional frequency-domain flutter analysis, which is used to formulate an efficient algorithm for computation of robust flutter boundaries. The proposed method is successfully applied to an F-16 sample test case with uncertain external stores aerodynamics, showing that standard tools for structural dynamics and unsteady aerodynamics can be used to perform robust flutter analysis with only modest additional modeling.
The optimal design of a cantilever wing in incompressible flow is considered. The wing is modelled as a full depth sandwich wing using finite element analysis. A doublet lattice panel method is used for computation of the unsteady aerodynamic loads. The weight of the wing is minimized using the thicknesses of the composite face sheets as design variables subject to constraints on flutter and divergence speed. Imperfection sensitivity of the final design is analysed and general aspects of imperfection sensitivity in optimization subject to aeroelasticity constraints are discussed in some detail.
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