Design, Analysis And Testing Of An Aircraft Wing Model With Morphing Mechanism

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Abstract

Wing morphing has the potential to significantly improve the performance of an aircraft. The aerospace industry currently relies on control surfaces for changing aircraft wing geometry for different parts of the flight envelope. The needs for reduced fuel consumption and improved flight capability are motivating the aerospace industry to explore alternatives such as wing morphing. Based on this premise, the design, analysis and testing of an aircraft wing model with morphing mechanism is presented. A design study was initially performed to verify the feasibility of the adaptive wing to entirely actuate using shape memory alloy wires (SMA). Finite element method (FEM) was used to assess the capability of the wing to withstand the aerodynamic load and to morph to a desired shape. The actuators’ forces and displacements were also evaluated by finite element simulation.The airframe of a morphing wing, consisting of two ribs made of 14 segments and interconnected through torsional stiffened hinges, was developed. The two ribs were connected through spars with circular cross sections. In the simulation, a skin was considered as the overlapping sliding segments. Morphing of the wing was achieved by displacement of a designed linkage mechanism, using SMA wires installed inside the airframe. The SMA wires connect the front spar to the linkage mechanism via mounting brackets. Torsional and gas springs were considered for providing counter-resisting forces to the system. Actuation occurred by heating the SMA wires through continuous feeding of electric current.Finally, a prototype with rectangular plan section was manufactured and tested so as to demonstrate the morphing capability of the conceived structural layout. The results of the functional test showed high correlation levels with respect to numerical predictions, thus validating the modelling approaches implemented during the design phase. The wing appears to deform smoothly with the induction of very small stresses. A change in thickness ratio of up to 200 % was first achieved through static loading with a total force of 90 N. A 55 mm displacement of the linkage mechanism transformed the model from NACA 0012 to NACA 0036. A total of 4 SMA wires (2 wires per bundle) provided the force required to actuate the test demonstrator up to half the morphing intended. The strain on the wires was limited to 3.5 % to allow a complete shape recovery. This thesis presents the methodology and the results obtained from designing building and testing the proposed wing-morphing model.

Keyword(s)

Adaptive wing; Morphing wing; SMA; Shape morphing; Smart materials; Variable thickness wing

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