Optimal Configuration Design for the Variable Geometry Wing-Box

Abstract

In wing morphing, it is desirable to have a system that acts both as a load-bearing structure and a morphing mechanism, without any distinction between the two. When dealing with a rather large design space, designing for this requirement would be less challenging because the constituting structural elements could be topologically placed in a fashion to enhance the static characteristics of the system, without sacrificing its kinematic abilities. However, in the case of an aircraft wing, where the design space is highly restrictive, conventional approaches typically yield inefficient designs from a static perspective. Such restrictions have served as inspirations for the proposed concept of a reconfigurable system, which is able to alter its kinematic and static characteristics to act both as a mechanism and a high-stiffness structure. The optimal configuration design of this system, referred to as the variable geometry wing-box is discussed in this paper. The optimal configuration design problem is posed in two parts: 1) the optimal limb configuration, and 2) the optimal topological configuration. The former seeks the optimal design of the kinematic joints and links, while the latter seeks the minimal compliance solution to their placement within the design space. In addition to the static and kinematic criteria required for reconfigurability, practical design considerations such as fail-safe requirements and design for minimal aeroelastic impact are included as constraints in the optimization process. In the end, the optimal configuration for the variable geometry wing-box is presented, and its rigidity is validated using a reconfigurable prototype.