Multidisciplinary Wing Optimization Using a Wing Box Layout Concept and a Parametric Thickness Model

Abstract

A concept is presented here for simultaneous optimization of an aircraft wing shape and gauges of the corresponding structural wing box. The approach also follows the concept of a single common parametric description as a basis for structural and aerodynamic modelling. The coordinates of the segment corners or typical planform parameters like the wing sweep angle represent the design variables for planform variation. Control points of parametric Bezier surfaces are used to de¯ne the thickness distribution of the wing box structural elements (skin, ribs, and spars). This concept also takes into consideration common design rules for practicable wing box structures. The parametric description of the gauges of the wing box structural elements guarantees the creation of regular and smooth surfaces and thus supports the generation of practicable thickness distributions from the design engineer's point of view. To improve the optimization e±ciency a lumping of certain stress constraints using the Kreisselmeier/Steinhauser-Function was introduced. A generic wing design is presented as an application and test example for which conventional FE-based thickness optimiza- tions were already performed with various sweep angles. A further example is that of a wing with identical external geometry but with a more realistic wing box structure. Its ribs are perpendicular to the front spar and must be regenerated if the external geometry is modi¯ed.