Bilevel Design of a Wing Structure Using Response Surfaces

A methodology for performing bilevel structural optimization of aircraft wing structures is proposed. The overall design problem is decomposed into two levels: a wing (or upper) level and a panel (or lower) level. At the upper level the wing structure is evaluated and designed using a finite element model that is less detailed and contains fewer design variables compared to the actual structure. Constraints on the overall behavior of the structure, such as aeroelastic constraints or constraints on the tip deflection, are imposed a t this level. At the lower level more detailed models of certain portions of the structure are used to compute more complex failure modes and to design the details that were not included in the upper-level model. The upper and lower design levels are coordinated with one another using a set of response surface models. Proper coordination between the two levels is maintained through the transfer of stiffness and load information from the upper design level to the lower design level. Results obtained using the proposed technique are presented for a simple wing model.