04.1 - Aerospace Grade Materials, Structural Analysis, Fatigue and Damage Tolerance
OPTIMAL DESIGN OF STIFFENED PANELS UNDER BUCKLING CONSTRAINTS: A DESIGN METHODOLOGY CONSIDERING CAD-BASED PARAMETERIZATION WITH SIMULTANEOUS LAYOUT AND SIZING OPTIMIZATION
H. Rahman¹, R. De Breuker¹, S.G.P. Castro¹; ¹Delft University of Technology, Netherlands
Stiffened panel is widely used in aerospace and marine applications owing to its higher stiffness and strength-to-weight ratio. Since these panels are thin walled structures, therefore they are more susceptible to fail under buckling loads. Optimization techniques have been employed to design stiffened panels with minimum weight whilst ensuring their enough resistance against buckling failure. The key factors which influence the optimal weight of a stiffened panel include the choice of material, panel and stiffeners sizing, stiffeners layout and the type of the stiffener. The layout parameters describe the arrangement of the stiffeners on the panel including their location and orientation. There exist various research studies in which the optimal stiffened panel design was achieved through layout optimization. The common trend in all these studies was the use of non-gradient based optimization techniques which are computationally expansive and therefore can allow only a very limited number of design variables. This shrinks the design space which ultimately limits the performance improvement. The probable reasons for using non-gradient based techniques are their easy implementation and to avoid the challenging task of calculating the shape gradients which are required because a change in the stiffener layout will change the shape of the stiffened panel. The motivation of the current research is to use gradient based methods for simultaneous layout and sizing optimization of stiffened panels under buckling constraints. Another challenge which is addressed here is the use of CAD-based geometry parameterization for the stiffened panels. An innovative design strategy for simultaneous layout and sizing optimization has been developed and employed on stiffened panels. The use of gradient based method opens up the design space which is currently restricted because of the use of non-gradient based methods and therefore great improvement in the structural performance of the s