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Morphing wings offer potential efficiency and performance benefits for aircraft fulfilling multiple mission requirements. However, the design of shape adaptable wings is limited by the inherent design trade-offs of weight, aerodynamic control authority, and load-carrying capacity. A potential solution to this trilemma is proposed by exploiting the stiffness adaptability of thin, curved structures which geometric instability results in two statically stable states. We design and manufacture a morphing wing section demonstrator composed of two compliant 3D printed ribs monolithically embedded with the proposed bi-stable elements. The demonstrator’s structural response is numerically modelled and compared with experimental results from a static loading test. A deflection field of the response under mechanical actuation is obtained through digital image correlation. Numerical and experimental results indicate the capability of the wing section to achieve four distinct stable configurations with varying global stiffness behavior.

A trade-off exists in compliant morphing structures between weight, adaptability, and load-carrying capacity. A truss-like structure utilizing a selectively stiff, bi-stable element is proposed to provide a solution to this problem. The design space of the element is explored in a parameter study using a finite element model. The element is embedded in a rib to correlate its behavior to that of the element in isolation. Finally, an aeroelastic analysis is conducted on the rib to determine the response of the structure to aerodynamic loading.

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Morphing wings provide a potential avenue to improve aerodynamic performance of aircraft operating at multiple design conditions. Nevertheless, morphing wing design is constrained by the mutually exclusive goals of high load-carrying capacity, low weight, and sufficient aerodynamic control authority via conformal shape adaptation. This trade-off can be addressed by exploiting the stiffness selectivity and shape “lock-in” properties enabled by using bistable beam-like elements within compliant structures. In this paper, we present an aero-structural optimization method to realize morphing structures with selective stiffness and shape “lock-in” capability from embedded bistable elements. We leverage an embeddable beam element with an invertible curved arch that provides stiffness selectivity and camber variation to the proposed rib geometry. Optimization objectives and constraints are designed to maximize the structure’s stiffness change and camber morphing “lock-in” effect when operating at two distinct flight conditions. Using the optimization results, we manufacture a wing section demonstrator with selective stiffness and “lock-in” morphing featuring two optimized ribs, a load-carrying skin made of a carbon reinforced laminate, Macro-Fiber Composite (MFC) actuators, and a servo-controlled mechanism for switching the bistable elements’ states. The power and energy requirements of actuating and holding a target deflection are experimentally measured and compared. The results show that the bistable elements can assist in holding a target deflection at a reduced energy cost. Finally, we test the experimental demonstrator in a low-speed wind tunnel demonstrating the load carrying capability and lift variation achieved from switching states.

the first sentence is incomplete. The first two sentences of the first paragraph should read:Advances in adaptive structures have led to renewed interest in continuous shape-changing morphing aircraft in the aerospace community [Valasek, 2012]. These designs are advantageous because they allow for optimal operation of an aircraft subject to a multi-objective mission with unique requirements and operational conditions at each stage [1,2].