Design Optimization of Airframe Structures

Abstract

A wing design optimization study is conducted to determine the effect of the configuration variable, sweep, on the minimum weight with strength and flutter constraints. In addition to sweep, the thicknesses of the plates are considered as variables in the optimization. The wing is subjected to two maneuver loads, a 6-g symmetric pull up and an antisymmetric roll condition combined with a 1-g steady flight. The multidisciplinary optimization systems, ASTROS, was used in the design study. The same system was used in calculating the static airloads. The study is divided into three categories. In category I the wing is optimized for the static loads with stress and size constraints. The optimum designs are then subject to a flutter analysis in category II. In category III the wing is optimized for the same loading conditions, but in addition to stress and size constraints a flutter constraint is imposed. The optimal designs are found to be relatively insensitive to wing sweep.