Global/local structural wing design using response surface techniques

Abstract

A new methodology for performing global/local design optimization of large wing structures is described. A simple but flexible interface between the global and local design optimization codes is constructed using response surface techniques. This interface is structured so as to minimize the changes required in either the existing global design code or the existing local design code(s). Proper coupling between the global and local levels is maintained through the transfer of global stiffness information from the global design code to the local design code. Using a finite number of local analysis/design cycles, the optimal panel obtained from the local design code is approximated by a response surface model over appropriate ranges of the loading and stiffness parameters. During the global/local design iterations, the resulting response surface model replaces the local design code via a weight constraint. Results obtained using the proposed technique are presented for a simple global wing model. 'Graduate Research Assistant, Member AIAA * Professor, Associate Fellow AIAA * Professor, Fellow AIAA ' Senior Member, AIAA Introduction This paper describes a new methodology that may be used to perform global/local design optimization of large wing structures. Typically, when global/local design optimization is performed, the interface between the local design code and the global design code must be carefully constructed in order to take into account the specific requirements of each code. In addition, the operation of the local design code is often de-coupled from the global design code because the local code is not usually provided with information about how its actions may affect global level constraints. The global/local interface proposed in the present work, which is based on response surface techniques, is designed to avoid these difficulties. Once this interface has been implemented at the local level, any number of local design codes may be utilized in the design process without requiring additional changes in either the local or global design codes. The local design code(s) may potentially incorporate a variety of local failure constraints, such as buckling, strength, damage tolerance, and manufacturing constraints while taking into account a variety of local structural details. Because global stiffness information is made available at the local level, proper coupling is Copyright © 1997 by S.A. Ragon. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission.