VARIABLE-COMPLEXITY RESPONSE SURFACE APPROXIMATIONS FOR WING STRUCTURAL WEIGHT IN HSCT DESIGN

Matthew Douglas Kaufman

Thesis submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of

master of science

Approved

Bernard Grossman, Co-Chair
Raphael T. Haftka, Co-Chair
William H. Mason
Layne T. Watson

April 25, 1996
Blacksburg, Virginia

Abstract

A procedure for generating and using a polynomial approximation to wing bending material weight of a High Speed Civil Transport (HSCT) is presented. Response surface methodology is used to fit a quadratic polynomial to data gathered from a series of structural optimizations. Several techniques are employed in order to minimize the number of required structural optimizations and to maintain accuracy. First, another weight function based on statistical data is used to identify a suitable model function for the response surface. In a similar manner, geometric and loading parameters that are likely to appear in the response surface model are also identified. Next, rudimentary analysis techniques are used to find regions of the design space where reasonable HSCT designs could occur. The use of intervening variables along with analysis of variance reduce the number of polynomial terms in the response surface model function. Structural optimization is then performed by the program GENESIS on a 28-node Intel Paragon. Finally, optimizations of the HSCT are completed both with and without the response surface.

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