1,721,015 research outputs found
On the experimental characterization of morphing structures
No full textA major difficulty in the design of morphing devices for aircraft wings is to reach an adequate compromise between high load-carrying capacity to withstand aerodynamic loads and sufficient flexibility to achieve better aerodynamic performance. Such counteracting and demanding targets lead to an increased structural complexity whose experimental characterization is a matter of high priority prior to the ultimate physical integration into the aircraft structure. Compared to the passive counterpart, morphing devices enable augmented capabilities by locally adapting wing shape and lift distribution through either a quasistatic or dynamic deflection, with excursions ranging into a few units of degrees, positive and negative.This chapter provides an overview of the verification approaches suitable for morphing devices ranging from the basic concepts applicable to individual subsystems up to the global experimental analysis of the integrated system. A number of test objectives are illustrated at both component and system level, providing practical tips for the experimental analysis of morphing structures combining both compliant structural systems and multibox self-contained actuation mechanisms
SARISTU: Adaptive Trailing Edge Device (ATED) design process review
No full textSARISTU was a big cooperation project granted by the European Commission, 7th Framework Programme, carried out between 2011 and 2015. It dealt with smart aeronautic structures, both morphing and sensored; its main target was to demonstrate the feasibility of designing, manufacturing and operating in representative environment, instrumented structures. Till now, it represents the major effort carried out within the European Union on the development of adaptive architectures for air systems. Inside that big activity, the realization of an Adaptive Trailing Edge Device (ATED) for wing camber adaptations aimed at compensating the weight reduction following the fuel consumption during cruise was addressed. It made the core of investigations target variable geometry aircraft components together with two other analyses concerning the development of shape-changing winglet and droop nose. ATED activities were conducted by the Italian Aerospace Research Centre (CIRA) in tight cooperation with the University of Napoli, “Federico II”, who coordinated a group of 12 different partners from 8 different nations (France, Germany, Greece, the Netherlands, Israel, Spain, Turkey, and Italy). In this paper, an integral synthesis of that work is reported, with a focus on the definition and realization of the components of the presented device. The publication is in fact meant as the first part of a series that is aimed at overviewing the whole adaptive trailing edge development, till wind tunnel tests execution. Such a concise report is a critical and harmonized review of what have been performed by many colleagues spread all over Europe, all of which are duly recalled in the reported bibliography where the reader may access more detailed information and descriptions. In detail, the paper starts with a general introduction of the concept and its aims, to move to the specs definition immediately after. Then, it deals with a short but comprehensive description of the main ATED components: structural skeleton, skin, actuation and sensing systems. It is worth remarking that the paragraph dedicated to the body frame includes some discussion about aeroelastic assessment and manufacture, seen as complementation for a complete assessment of the design constraints
Morphing Wing Technologies, Large Commercial Aircraft and Civil Helicopters
No full textMorphing Wings Technologies: Large Commercial Aircraft and Civil Helicopters offers a fresh look at current research on morphing aircraft, including industry design, real manufactured prototypes and certification. This is an invaluable reference for students in the aeronautics and aerospace fields who need an introduction to the morphing discipline, as well as senior professionals seeking exposure to morphing potentialities. Practical applications of morphing devices are presented-from the challenge of conceptual design incorporating both structural and aerodynamic studies, to the most promising and potentially flyable solutions aimed at improving the performance of commercial aircraft and UAVs. Morphing aircraft are multi-role aircraft that change their external shape substantially to adapt to a changing mission environment during flight. The book consists of eight sections as well as an appendix which contains both updates on main systems evolution (skin, structure, actuator, sensor, and control systems) and a survey on the most significant achievements of integrated systems for large commercial aircraft. Provides current worldwide status of morphing technologies, the industrial development expectations, and what is already available in terms of flying systems Offers new perspectives on wing structure design and a new approach to general structural design Discusses hot topics such as multifunctional materials and auxetic materials Presents practical applications of morphing devices. © 2018 Elsevier Ltd. All rights reserved
Preliminary Design of an Adaptive Aileron for Next Generation Regional Aircraft
No full text“Inspiration from nature” is the key words that lies behind the morphing idea. Just as bird helped to inspire the design of the warping mechanism of the Wright Flyer, nature offers a philosophy inspiration for morphing wing design. Since aviation origin, a connection between bio-inspiration and aeronautical engineering can be found which has led through years at the current idea of a morphing wing as a mechanism capable to adapt its shape as well as the flight conditions change. Design of morphing wings at increasing TRL is common to several research programs worldwide, especially aimed at improving their associated benefits (optimize aerodynamic efficiency, fuel consumption reduction, decrease of COx and NOx emission, etc.) and overcoming classical limits (increasing system complexity, certification, reliability and so on). In this framework, the CRIAQ MD0505 project was launched; a joint research program between Canadian and Italian academies, research centers and leading industries. The target of this research cooperation is the development of combined smart structures systems on a full scale wing tip of a next generation regional aircraft. The complex device combines a modifiable airfoil thickness with a camber morphing aileron. This paper focuses on the preliminary design and the numerical modeling of the aileron architecture. The structural layout consists of a number of deformable ribs, each made of three consecutive blocks connected each other by hinges. Further cross connections between pair of elements, make the system a SDOF finger-like mechanism. The aileron is moved by servo rotary load bearing actuators which drive a kinematic chain and sustain the external aerodynamic pressure distribution. A FE model of the entire architecture was released to verify the structural integrity under prescribed operational conditions
SMA for aeronautics (2nd edition)
No full textThe advantages of using shape memory alloys (SMAs) in aeronautical applications are various (compactness, lightness, etc.). Some of the most interesting aeronautical applications involving SMAs are briefly examined with a focus on wing morphing, propulsion systems, and noise reduction. In particular, the potential of SMAs to realize adaptive flaps according to two different architectures, compliant and kinematic, is discussed, examining the pros and cons
Active vibration control of a mounting bracket for automotive gearboxes
Full text linkThe aim of this paper is to investigate the use of active vibration control in automotive gearboxes mounting brackets to reduce tonal disturbances. A combination of piezoelectric accelerometers and an internally preloaded piezo stack actuator is used to counteract their unbalanced caused vibrations. Initially, a numerical modal analysis was carried out to identify the normal modes in the frequency range of interest. The piezo stack was simulated by a ROD element and its effect numerically characterized. The upper and lower faces of the stack were mechanically coupled with the bracket structure, whereas the active control strategy involved the relative displacement of two opposite points of the bracket. To this aim, dedicated interfaces were designed to integrate the stack into the mounting bracket. In order to control the vibrations in correspondence of the second bending mode (1599.4Hz), the primary disturbance, simulated by a shaker, was modelled in the frequency domain using a white noise signal. A narrow window of 20Hz was initially selected as the control system domain. Then, this frequency range has been made gradually wider around the resonance peak, in order to optimize the control effect, and then extended up to 80 Hz when undesired effects occurred. Primary and secondary control plants were firstly numerically fitted from the measured responses and excitations using system identification techniques, and then used for the active controller design and simulations
Polymer based morphing skin for adaptive wings
No full textThe development of elastomeric materials for adaptive wings focuses on the elasticity at -55 °C to ensure morphing at cruise altitudes. FEM simulations and mechanical tests are carried out to optimize fatigue and aging properties of this new multi-material device. Two large skin panels are manufactured and successfully assembled into a true-scale wind tunnel demonstrator for the experimental validation of adaptive trailing edge device functionality in simulated operative conditions
Fiber Optic Shape Sensor System for a Morphing Wing Trailing Edge
Full text linkThe objective of this work is to present a conceptual design and the modelling of a distributed sensor system based on fiber optic devices (Fiber Bragg Grating, FBG), aimed at measuring span-wise and chord-wise variations of an adaptive (morphing) trailing edge. The network is made of two different integrated solutions for revealing deformations of the reference morphing structure. Strains are confined to typical values along the span (length) but they are expected to overcome standard ranges along the chord (width), up to almost 10%. In this case, suitable architectures may introduce proper modulations to keep the measured deformation low while preserving the information content. In the current paper, the designed monitoring system combines the use of a span-wise fiber reinforced patch with a chord-wise sliding beam. The two elements make up a closed grid, allowing the reconstruction of the complete deformed shape under the acceptable assumption that the transformation refers to regular geometry variations. Herein, the design logic and some integration issues are reported. Preliminary experimental test results are finally presented
Feasibility study for a tonal vibration control system of a mounting bracket for automotive gearboxes
No full textA conceptual design of an active device able to attenuate the tonal vibrations of a mounting bracket for automotive gearboxes is addressed in this paper. A preloaded piezo stack actuator is used to counteract the unbalanced vibrations of the component by monitoring its operational deformations. Firstly, a numerical modal analysis is carried out to characterize the normal modes in the frequency range of interest. The piezo stack is simulated by a rod element and its effect is numerically characterized. The upper and lower faces of the stack are mechanically coupled with the bracket structure, whereas the active control deals with the relative displacement of two points of the bracket. The primary disturbance was simulated by a shaker to control the vibrations in correspondence of the second bending mode (around 1.6 kHz). A 20 Hz narrow band was additionally selected as the control window. Then, this frequency range was enlarged around the resonance peak in order to optimize the control effect, till 80 Hz to investigate the resulting effects. Finally, focus is given to the structural damping by assessing its impact on the control forces and phases to cancel the deformation along the contact direction. The description of the experimental results concludes this work by generally confirming the numerical expectations
- …
