Flexible Multibody Dynamics and Sensitivity Analysis in the Design of a Morphing Leading Edge for High-Performance Sailplanes

Abstract

High-performance sailplanes have a wide speed range. Form-variable wings with a morphing leading edge in combination with a trailing flap for a high-speed and a lowspeed configuration have shown to increase the performance. In the present work, a morphing wing leading edge modeled as a system constituted of a flexible external wing skin and an actuation mechanism with rigid bodies is investigated. Flexible multibody dynamics with the floating frame of reference formulation is applied to analyze the behavior of the system during the motion from the high-speed configuration to the low-speed configuration. The methodology includes generalized-a time integration with Newton–Raphson iterations and efficient design sensitivity analysis. The design sensitivities are calculated with a semi-analytical approach based on direct differentiation. Of particular interest in the simulation are the deviations of the wing profile from the target shape in morphed configuration and the stresses in the external wing skin. The design variables used in the sensitivity analysis include geometric parameters, material parameters and loading parameters. The introduced methods show high efficiency and provides reliable results. The sensitivities are visualized giving an easy interpretation of the sensitivity values and in understanding how the design variables can be changed to improve the design. The sensitivity computations enable further investigations such as uncertainty analysis or gradient-based design optimization of the system.