Optimization of a variable-stiffness skin for morphing high-lift devices

Abstract

One of the possibilities for the next generation of smart high-lift devices is to use aseamless morphing structure. A passive composite variable-stiffness skin as asolution to the dilemma of designing the structure to have high enough stiffness towithstand aerodynamic loading and low stiffness to enable morphing is proposed. Thevariable-stiffness skin is achieved by allowing for a spatial fibre angle and skin thicknessvariation on a morphing high-lift system. The stiffness distribution is tailored to influencethe deformation of the structure beneficially. To design a realistic stiffness distribution, itis important to take aerodynamic and actuation loads into account during theoptimization. A two-dimensional aero-servo-elastic framework is created for thispurpose. Skin optimization is performed using a gradient-based optimizer, wheresensitivity information is found through application of the adjoint method. Theimplementation of the aero-servo-elastic environment is addressed and initialoptimization results presented. The results indicate that a variable-stiffness skinincreases the design space. Moreover, the importance of taking the change inaerodynamic loads due to morphing skin deformation into account during optimization isdemonstrated.