Distributed actuation concepts for a morphing aileron device

Recent Progress in Some Aircraft Technologies (InTech), 2016

European Union is involving increasing amount of resources on research projects that will dramatically change the costs of building and operating aircraft in the near future. Morphing structures are a key to turn current airplanes to more efficient and versatile means of transport, operating into a wider range of flight conditions. The concept of morphing may aim at a large number of targets, and its assessment strongly depends on the final objectives and the components where it has to be deployed. Maneuver, takeoff, landing, cruise conditions, just to cite few and very general examples, have all their own peculiarities that drive the specifications the wing shape change has to suit on. In general, an adaptive structure ensures a controlled and fully reversible transition from a baseline shape to a set of different configurations, each capable of withstanding the relative external loads. The level of complexity of morphing structures naturally increases as a consequence of the augmented functionality of the reference system. Actuation mechanisms constitute a very crucial aspect for adaptive structures design because has to comply variable wing shapes with associated loads and ensure the prescribed geometrical envelope. This chapter provides a presentation of the state of the art, technical requirements, and future perspectives of morphing ailerons. It addresses morphing aircraft component architecture and design with a specific focus on the structural actuator system integra‐ tion. The approach, including underlying concepts and analytical formulations, combines methodologies and tools required to develop innovative air vehicles. Aileron is a very delicate region, where aeroelastic phenomena may be very important because of the very reduced local stiffness and the complex aerodynamics, typical of the wingtip zone. On the other side, this wing segment showed to be the one where higher cruise benefits could be achieved by local camber variations. This target was achieved while keeping the typical maneuver functions.

Aerospace

The design and testing of a high-bandwidth continuous actuator for aeronauticalapplications is presented hereinafter. The actuator has a dual goal of controlling both the aeroelasticbehaviour and the flight mechanics of the model in which it is installed. In order to achieve theseaims, the actuation bandwidth of the active aerofoil, as well as its static camber variation, have to besufficiently high. The camber morph is achieved by using tailored piezoelectric patches in a sandwichconfiguration with a linear trailing edge slider to allow the necessary compliance. The morphingactuator is designed for a NACA 0018 aerofoil with a chord of 300mmand a span of 40 mm. Static anddynamic experimental tests are carried out on a prototype, and a camber variation control techniqueis implemented. It is proved that the actuator bandwidth is up to 25 Hz and the equivalent maximumdeflection is 15 degrees. This solution is shown to be a viable light-weight alternative to theconventional brushless/se...

Smart Structures and Materials 2003: Industrial and Commercial Applications of Smart Structures Technologies, 2003

Morphing aircraft structures can significantly enhance air vehicle performance. This paper highlights ongoing work to design novel compliant mechanisms that efficiently morph aircraft structures in order to exploit aerodynamic benefits. Computational tools are being developed to design structures that deform into specified shapes given simple actuator inputs. In addition, these synthesis methods seek to optimize the stiffness of the structure to minimize actuator effort and maximize the stiffness with respect to the environment (external loading). These tools have been used to study two different types of morphing systems: (i) variable geometry wings and (ii) high-frequency vortex generators for active flow control. Several case studies are presented which highlight the design approach and computational and experimental results of these morphing aircraft systems.

Actuators

The present work focuses on the actuation system of a morphing winglet conceived to adaptively alter the load distribution on the wing, to reduce its stress level and enhance the climb performance. The winglet is equipped with two flaps, independently controlled by dedicated kinematic chains, in turn moved by linear electro-magnetic actuators. An interior finger-like architecture, relevant part of the actuation system, makes particularly smooth the deflections. Starting from a survey on similar applications and on the basis of the requirements at aircraft level, the specifications of the actuation system were defined. A preliminary outline of the system was thus addressed, identifying the main components, their role and their working mode. Then, the advanced design was finalized. To this scope and considering the large displacements that characterize this kind of application, a non-linear finite element approach was implemented. Both the deflection capability with and without loads ...

Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2015

The paper presents the design and the experimental validation of a position controller for a morphing wing application. The actuation mechanism uses two DC motors to rotate two eccentric shafts which morph a flexible skin along two parallel actuation lines. In this way, the developed controller aim is to control the shape of a wing airfoil under different flow conditions.

Solid State Phenomena, 2017

Amongst current aircraft research topics, morphing wing is of great interest for improving the aerodynamic performance. A morphing wing prototype has been designed for wind tunnel experiments. The rear part of the wing - corresponding to the retracted flap - is actuated via a hybrid actuation system using both low frequency camber control and a high frequency vibrating trailing edge. The camber is modified via surface embedded shape memory alloys. The trailing edge vibrates thanks to piezoelectric macro-fiber composites. The actuated camber, amplitude and frequency ranges are characterized. To accurately control the camber, six independent shape memory alloy wires are controlled through nested closed-loops. A significant reduction in power consumption is possible via this control strategy. The effects on flow via morphing have been measured during wind tunnel experiments. This low scale mock-up aims to demonstrate the hybrid morphing concept, according to actuator capabilities point...

MDPI-Aerospace, 2019

Within the framework of the Clean Sky-JTI project the design and technological demonstration of a novel wing flap architecture were addressed. Research activities were carried out to substantiate the feasibility of morphing concepts enabling flap camber variation in compliance with the demanding safety requirements applicable to the next generation green regional aircraft. The driving motivation for the investigation on such a technology, was found in the opportunity to replace a conventional double slotted flap with a single slotted camber-morphing flap assuring similar high lift performances -in terms of maximum attainable lift coefficient and stall angle- while lowering emitted noise and system complexity. The actuation and control logics aimed at preserving prescribed geometries of the device under variable load conditions are numerically and experimentally investigated with reference to an “iron-bird” demonstrator. The actuation concept is based on load-bearing actuators acting on morphing ribs, directly and individually. The adopted un-shafted distributed electromechanical system arrangement uses brushless actuators, each rated for the torque of a single adaptive rib of the morphing structure. An encoder-based distributed sensor system generates the information for appropriate control-loop and, at the same time, monitors possible failures in the actuation mechanism. Further activities were then discussed in order to increase the TRL of the validated architecture.

2006

Morphing aircraft are flight vehicles that change their shape to effect both a change in the mission of the aircraft and to perform flight control without the use of conventional control surfaces. The key to morphing aircraft is the full integration of the shape control into the wing structure, and this is most easily achieved using composite structures. The design of these vehicles must take full account of the aerodynamic loads and must carefully consider the power requirements for shape control to ensure an overall performance benefit. This paper overviews three possible methods to achieve the required structural compliance that are under investigation at Bristol. The first is the design of the internal structure to produce a compliant mechanism that achieves the required aerofoil deformation using a small number of actuators. The second is the use of stiffness tailoring, incorporating the performance objectives, together with material constraints such as buckling and manufacturing requirements. The final approach is the use of multi-stable structures to perform large shape changes. For these structures, no force is required to maintain their stable configurations. The general features of these approaches will be described and illustrated using simulated and experimental results.

Physics Procedia, 2010

An experimental morphing laminar wing was developed to prove the feasibility of aircraft fuel consumption reduction through enhancement of the laminar flow regime over the wing extrados. The morphing wing prototype designed for subsonic cruise flight conditions (Mach 0.2…0.3; angle of attack -1…+2°), combines three principal subsystems: (1) flexible extrados, (2) rigid intrados and (3) an actuator group located inside the wing box. The morphing capability of the wing relies on controlled deformation of the wing extrados under the action of shape memory alloys (SMA) actuators. A coupled fluid-structure model of the morphing wing was used to evaluate its mechanical and aerodynamic performances in different flight conditions. A 0.5 m chord and 1 m span prototype of the morphing wing was tested in a subsonic wind tunnel. In this work, SMA actuators for morphing wings were modeled using a coupled thermo-mechanical finite element model and they were windtunnel validated. If the thermo-mechanical model of SMA actuators presented in this work is coupled with the previously developed structureaerodynamic model of the morphing wing, it could serve for the optimization of the entire morphing wing system.

AIAA Atmospheric Flight Mechanics Conference 2012, 2012

The paper presents a smart way to actuate and to control the airfoil shape of a morphing wing. The actuation system development is based on some smart material actuators like Shape Memory Alloys, disposed in two parallel actuation lines, and its control is performed by using a fuzzy logic PD controller of Mamdani type.