Dissertations / Theses on the topic 'Morphing composites'
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Chillara, Venkata Siva Chaithanya. "Multifunctional Laminated Composites for Morphing Structures." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524104865278235.
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Ruangjirakit, Kitchanon. "Polyurethane corrugated composites for morphing wing applications." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/18064.
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The morphing wing can be considered as a wing with seamless control surfaces and high-lift devices, which is capable of changing its shape during flight. As a result, an aircraft with the morphing wing can fly multi-mission tasks effectively and efficiently. The morphing wing should be stiff in spanwise direction to withstand aerodynamic and actuation loads while, in chordwise direction, the wing should be compliant in order to allow shape change. In this thesis, corrugated carbon fibre reinforced polyurethane composite is introduced as a candidate for the skin of morphing wing applications as the corrugated composite is considered highly anisotropic. A parametric study of three corrugated profiles (sinusoidal, trapezoidal and U-shape) with differnet amplitudes and unit cell lengths was performed numerically using finite element analysis and compared with analytical model in order to investigate the effects of the corrugation geometry on the mechanical response under tensile load. The results indicate that the trapezoidal profile offers the lowest extensional stiffness followed by U-shape and sinusoidal, respectively. In terms of corrugation geometry, the extensional stiffness of the corrugation is inversely proportional to both unit cell length and amplitude. An aerodynamic analysis of an aerofoil with corrugated lower skin was performed experimentally at four different Reynolds numbers and compared with an aerofoil with smooth skin. The conclusion drawn from the wind tunnel testing is that the aerofoil with corrugated skin on the pressure side is feasible to be used for a morphing wing of a small unmanned aerial vehicle (UAV) that operates at Reynolds number of approximately 10[superscript 5]. A bench-top demonstrator was constructed as a proof of concept and experimentally tested for repeatability and structural integrity. Moreover, the mechanical advantage was evaluated through a simple experiment.
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Panesar, Ajit S. "Multistable morphing composites using variable angle tows (VAT)." Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574264.
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The continual need to better aircraft performance is increasingly prompting designers towards the realisation of morphing structures. One such enabling morphing technology are "multistable composites", and interest in them stems from the fact that they are able to sustain significant changes in shape without the need for a continuous power supply. This research benefits from the tow-steering technique to develop laminates with curved fibre-paths or Variable Angle Tows (VAT) in a ply (i.e. exploiting the anisotropy of composites), to introduce residual thermal stresses capable of imparting bistability. The principle idea is that VAT laminates can impart bistability with the new feature of ensuring fibre continuity within the wider structure facilitating structural integration (i.e. blending of lay-ups across components). Additional structural strength is shown to be imparted due to the load path continuity achieved via the tow-steering technique. The thermally induced bistable behaviour of VAT laminates is investigated through Finite Element (FE) modelling and experimental studies. The effect on the stable shapes for variations in the resin layers, fibre volume fraction (Vf), resin thermal expansion and laminate thickness are reported and found to be influential (from high to low) in the same quoted order. An approach, aiding the development of well- defined finite element models that are capable of predicting the bistable behaviour of manufactured laminates, is presented. It is shown that despite the inherent variabilities in laminates, a shell model capturing sufficient detail (i.e. resin layer[s), ply thicknesses and the Vf of a ply) is successful in predicting the cured shape(s). An optimisation based design framework aimed at realising the morphing potential of VAT laminates is presented. A morphing alternative to the plain flap is achieved, and the two potential solutions: one aiming to maximise the deployed flap-angle, and the other to attain maximum flap-angle increment, are discussed. Moreover, a good agreement exists between the FE predictions and the experimental observations for the manufactured laminates, demonstrating the feasibility of the morphing flap concept.
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Mulakkal, Manu. "Development of bio-inspired cellulosic smart composites for morphing." Thesis, University of Bristol, 2018. http://hdl.handle.net/1983/6c3e48d3-78f7-4ae3-a50d-2dd7f0f65857.
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Materials capable of self-actuation and architectures facilitating re-configuration are highly valued and profoundly sought-after for numerous applications in the fields of robotics, deployable and morphing structures. Here, a bio-inspired approach to realising a programmable materials system capable of morphing was explored and implemented with a specific focus on the sustainability of the material components. The deployment of manually folded paper architectures using a fluid medium as the morphing stimulus presents a simple and inexpensive methodology capable of self-actuation. The materials-based as well as the stimuli parameters of this system were found to be programmable to control the actuation response of folded paper architectures. These results confirmed the suitability of cellulose as a cost effective and sustainable smart material capable of further functionalisation, and thus justified its consideration in developing programmable morphing systems. Following nature’s inspiration, a strain-gradient mediated methodology for self-folding paper architectures was realised by locally patterning ‘fold-lines’ with a compatible hydrogel system. The architectures were designed to actuate along the principles of paper folding techniques such as origami and kirigami thus providing proven and elegant programmability and actuation attributes. As such, a novel methodology for self-folding and subsequent stimuli responsive deployment of cellulosic architectures was established. The developments in 3D printing (3DP) technology allow the controlled placement of building materials in 3D space and this feature was harnessed to complement the strain-gradient mediated actuation of the cellulosic substrates. Therefore, a bespoke bio-inspired cellulose-hydrogel (carboxymethyl cellulose - CMC) composite for 3D printing was developed which can morph in the time domain (4D) according to the design rules developed from the previous chapters to mimic the actuation of responsive cellulosic structures observed in nature. Consequently, these responsive materials permit 4D printing - a process which pertains the transformation of 3D printed forms with respect to time. In this material system, the cellulose-hydrogel composite constitutes the programmable substrate and the CMC hydrogel acts as the localised component responsible for actuation. The strategy of drying and crosslinking following 3D printing results in a high fibre volume fraction cellulosic composites. The versatility of the materials and fabrication strategies demonstrated here enables the development of complex morphing architectures from computer aided design files with the tuneable material and structural features permitting programmability of the actuation responses. As such, this project demonstrates the realisation of sustainable cellulosic architectures capable of morphing via 4D Printing.
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Mattioni, Filippo. "Thermally induced multi-stable composites for morphing aircraft applications." Thesis, University of Bristol, 2009. http://hdl.handle.net/1983/1a808d25-f44d-42b9-8c43-d5664f1d2417.
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This research focuses on the realisation of 'shape-adaptable' systems through unsymmetrical laminates. The residual stress field which is built-into this type of laminates, is used to obtain panels with two or more equilibrium states. Such systems provide a possible solution for the realisation of morphing structures because they allow to simultaneously fulfil the contradictory requirements of flexibility and stiffness.
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Arrieta-Diaz, Andres Felipe. "Nonlinear Dynamics and Control of Bi-stable Composites for Morphing Applications." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521093.
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Wang, Bing. "Viscoelastically prestressed composites : towards process optimisation and application to morphing structures." Thesis, University of Hull, 2016. http://hydra.hull.ac.uk/resources/hull:15173.
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This thesis covers research that focuses on facilitating the industrial application of viscoelastically prestressed polymeric matrix composites (VPPMCs). With nylon 6,6 fibre as the reinforcement and polyester resin as the matrix material, unidirectional prestressed composite samples were produced and investigated, to expand the knowledge of existing VPPMC technology, and identify the potential application of viscoelastic fibre prestressing to morphing (shape-changing) structures. To produce a VPPMC, a tensile load is applied to polymeric fibre yarns to induce viscoelastically prestress; following load removal, the yarns are cut and moulded into a matrix. Previous research has shown that by using viscoelastic fibre prestressing within a composite, mechanical properties, such as tensile strength, flexural modulus and impact toughness can be increased by up to 50%. To further understand the underlying prestress mechanisms, the viscoelastic performance of nylon 6,6 fibre was investigated in terms of creep, recovery and recovery force measurement. By using various creep loading conditions, the viscoelastic behaviour of the fibre also provided the basis for investigations into the optimisation of load-time conditions for producing prestress. This provides the first step towards facilitating the production of VPPMCs for industrial application. Since there are increasing demands for using composites within morphing technology, the application of VPPMC principles to morphing structures was studied through both experimental and numerical investigations. The viscoelastic behaviour of nylon 6,6 fibre showed approximately linear viscoelasticity under 24 h creep conditions with up to 590 MPa stress. This was further verified through use of the time-stress superposition principle: instead of a nonlinear relationship as predicted by the well-known WLF equation, a linear relationship between the applied creep stress and the stress shift factor was found. By approaching the maximum creep potential of the fibre material, impact benefits from the prestressing effect were further improved by ~75% (at ~4.0% creep strain level). Charpy impact testing and recovery force measurement demonstrated that there was an optimum level of viscoelastic fibre prestressing to maximise the mechanical benefits. A viscoelastic deformation mechanism based on the three-phase microstructural model and latch-based mechanical model was then proposed. It was found that the fibre processing time for viscoelastically generated prestress could be significantly reduced from 24 h to tens of minutes. By employing the time-temperature superposition principle, the impact benefits from viscoelastically generated prestress under the standard 330 MPa, 24 h creep (at ~3.4% creep strain level), was found broadly to be the same as subjecting the yarns to 590 MPa for 37 min creep. Hence, there was no deterioration in prestress benefits from VPPMC samples produced under both creep conditions to an equivalent of 20,000 years at a constant 20˚C. Two viscoelastic creep strain levels (i.e. ~3.4% and ~4.0%) were evaluated through Charpy impact testing, the relationships between applied creep stress and the corresponding fibre processing time followed a logarithmic trend. This suggested that the fibre processing time for prestress could be reduced further, subjecting to avoiding fibre damage. The effects from increasing creep time were found to compare with increasing stress in terms of optimum VPPMC performance. Finally, the principle of viscoelastic fibre prestressing was successfully used to produce a bistable composite structure, which could snap from one stable cylindrical shape to another when subjected to external loading. The bistable structure was produced by bonding four prestressed strips to the sides of a thin, flexible resin-impregnated fibre-glass sheet. Here, bistability was achieved through pairs of strips orientated to give opposing cylindrical configurations within the sheet. Snap-through behaviour of the bistable structure was investigated through both experimental and numerical simulation; a snap-through mechanism was subsequently proposed based on these observations.
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Rubenking, Samuel Kim. "Dual Mode Macro Fiber Composite-Actuated Morphing Tip Feathers for Controlling Small Unmanned Aircraft." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78433.
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The transition of flight from manned to unmanned systems has led to new research and applications of technology within the field that, until recently, were previously thought to be unfeasible. The industry has become interested in alternative control surfaces and uses for smart materials. A Macro Fiber Composite (MFC), a smart material, takes advantage of the piezoelectric effect and provides an attractive alternative actuator to servos in the Small Unmanned Aerial Systems (SUAS) regime of flight. This research looks to take MFC actuated control surfaces one step further by pulling inspiration from and avian flight. A dual mode control surface, created by applying two sets of two MFCs to patch of carbon fiber, can mimic the tip feathers of a bird. This actuator was modeled both using Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD). Real-world static testing on a feather confirmed preliminary FEA results, and wind tunnel tests simulating assumed cruise conditions confirmed the feather would not exhibit any adverse structural behaviors, such as flutter or aeroelastic divergence. From its modeled performance on a wing using CFD, the MFC feather proved to be a success. It was able to produce a wing that, when compared to a traditional rectangular wing, yielded 73% less induced drag and generated proverse yaw. However, the MFC feathers alone, in the configuration tested, did not produce enough roll authority to feasibly control an aircraft.Master of Science
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Chabaud, Guillaume. "3D and 4D printing of high performance continuous synthetic and natural fibre composites for structural and morphing applications." Thesis, Lorient, 2020. http://www.theses.fr/2020LORIS563.
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L’impression 3D et plus spécifiquement la technique de Fused Filament Fabrication (FFF) de matériaux composites à renforts continus est un domaine d’étude en plein essor visant à pallier les faibles performances mécaniques rencontrées par les composites élaborés en impression 3D et ainsi ouvrir les champs d’applications (aéronautique, course au large…). Autre tendance, l’impression 4D qui permet de développer des matériaux stimulables (capteurs et/ou actionneurs) et d’envisager des structures architecturées complexes se déformant sous l’action de divers stimuli (humidité, électricité, température, pression…). Le travail de thèse s’inscrit dans ce contexte pluriel et vise à développer de nouveaux matériaux multifonctionnels par impression 3D et 4D. Dans un premier temps, le travail de thèse a pour objectif scientifique de comprendre les relations entre le procédé, la microstructure induite, les performances mécaniques et hygro-mécaniques en vue d’applications structurelles (aéronautique, course au large …) sur des matériaux composites renforcés de fibres synthétiques (carbone et verre) et naturelles (lin). La deuxième partie des travaux de thèse vise à développer des matériaux composites hygromorphes renforcés de fibres continues (synthétiques et naturelles) par impression 4D avec une architecture en bilame bio-inspirée de la pomme de pin. Le caractère conducteur des fibres de carbone est utilisé pour développer de nouveaux actionneurs electro- thermo-hygromorphes présentant un actionnement contrôlé et accéléré par rapport aux hygromorphes classiques. Enfin, la liberté de design offerte par l’impression 3D a été utilisée pour contrôler localement la rigidité et l’actionnement d’actionneurs composites renforcés de fibres de lin continues3D printing and especially Fused Filament Fabrication (FFF) technology for composite materials reinforced by continuous fibers is an emerging research field which aims to enhance the mechanical performance of 3D printing structures and to widen the field of application (aerospace, sailing…). Another trend, 3D printing allows to develop stimulable materials (sensor and/or actuators) and to consider parts with complex architecture that can be deployed under various stimulation (electricity temperature, pressure…). The present work is therefore part of this context and aims to develop new multi-functional materials elaborated by 4D printing. First, the scientific objective of this work is to better understand the relationship between the process, the induced microstructure, mechanical and the hygromechanical performances in order to target structural applications (aeronautic, sailing) for composite materials reinforced with synthetic fibers (carbon and glass) and natural fibers (flax). The second part of this work aimed to develop hygromorphic composites reinforced with continuous fibers (synthetic and natural) by 4D printing with a bioinspired bilayer architecture inspired by the pinecone scale. The conductive behavior of carbon fiber was used to create new electro-thermo-hygromorph actuators with controlled and accelerated actuation compared to conventional hygromorphs. Finally, the design freedom provided by 4D printing made it possible to control the local stiffness and actuation of composite actuators reinforced with continuous flax fiber
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Basit, Abdul. "Development and characterization of a shape memory polymer composite actuator for morphing structures." Thesis, Mulhouse, 2012. http://www.theses.fr/2012MULH8494/document.
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Les polymères à mémoire de forme (SMP) sont des matériaux qui peuvent revenir à leur forme d'origine lorsqu'un stimulus approprié (par exemple de la chaleur) est prévu. Ces polymères sont programmés par cycle de mémoire de forme qui se compose de deux parties: une partie de la programmation qui donne un effet mémoire de forme (SME) à savoir la forme temporaire pour le polymère et la partie de récupération où il revient à sa forme initiale. Les SMP ont une faible rigidité, donc, produisent de grandes déformations récupérables, mais produisent des forces de récupération faibles. Cependant, les composites SMP produisent des forces de récupération plus grandes car ils sont relativement rigide mais ont des souches moins récupérables. En outre, de forts actionneurs à mémoire de forme peuvent être produits si deux effets différents peuvent être combinés dans une structure unique. Une structure déjà active (par exemple des alliages à mémoire de forme) peut être intégré dans SMP. Par conséquent, un fort actionneur couplé peut être obtenu. [...]Shape memory polymers (SMPs) are the materials which can return to their original shape when a suitable stimulus (e.g. heat) is provided. These polymers are programmed through shape memory cycle that consists of two parts: programming part which gives shape memory effect (SME) i.e. temporary shape to the polymer and the recovery part which return it to its original shape. SMPs have low stiffness, therefore, produce large recoverable strains, but produce low recovery forces. However, SMP composites produce larger recovery forces as they are relatively rigid but have less recoverable strains. Moreover, strong shape memory actuators can be produced if two different effects can be combined in a single structure. An already active structure (e.g shape memory alloys) can be embedded in SMP. Consequently, a strong coupled actuator can be obtained. In this work, the shape memory property of CBCM composite (an active composite that works on bimetallic affect) has been studied. CBCM stands for controlled behavior of composite material. CBCM activeness and its SM property has been coupled together to obtain a strong actuator. SM property has been obtained through thermo-mechanical programming at a temperature higher than glass transition temperature (Tg) of Epoxy resin used for its fabrication. The CBCM actuating properties have been studied through different one-step recoveries (unconstrained, constrained and recovery under load). Moreover, different asymmetrical CBCM composites have been developed by changing the position and orientation of the different layers used. These have been studied for their different actuation properties. Similarly, multi-step recoveries (unconstrained and constrained) have also been performed to show multi step actuation capabilities in CBCM. The actuating properties of CBCM have also been compared with symmetrical composite (SYM) to show the advantage of coupled properties in CBCM. It has been found that CBCM has the ability to give high strain, high recovery forces. Also, it can recover under load and recover to its original position at the temperatures lower than the deforming temperature used in the programming cycle
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Terzak, John Charles. "Modeling of Microvascular Shape Memory Composites." Youngstown State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1389719238.
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Lo, Kin Man. "Surface deformation on composite patches by constrained morphing." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2493981.
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Giddings, Peter F. "Piezoelectrically actuated bistable composite laminates for structural morphing." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538161.
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Thill, Christophe. "Corrugated composite structures for morphing wing skin applications." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685422.
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This PhD study developed a composite structure with extreme orthotropic stiffness properties that offers the possibility for use as a skin panel in a morphing trailing edge control surface. The work has shown through an extensive literature review a lack of maturity in existing morphing skin concepts and thus the need for further research and development in this field. The focus of this investigation was on arranging conventional composite materials in a hierarchical structure that allows the combination of inherently different properties such as compliance and stiffness. This resulted in a fibre reinforced composite corrugated sandwich structure that is stiff parallel to the corrugation direction and relatively compliant, in tension and flexure, transverse to the corrugation direction. Experimental, analytical and numerical structural analysis was carried out to define the envelope within which corrugated structures can be designed to meet the requirements of a morphing skin. Further experimental and numerical aerodynamic investigations showed how to best implement these corrugated morphing skins in order to minimise the aerodynamic penalties. The combination of these results led to the design, manufacturing and testing of an aerofoil section with a morphing trailing edge control surface that incorporates a corrugated morphing skin. Low speed wind tunnel tests proved the concept but also highlighted limitations and raised suggestions for future work
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Tawfik, Samer Anwar. "Stability and morphing characteristics of bistable composite laminates." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24702.
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Thesis (Ph.D.)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Erian Armanios; Committee Member: D. Stefan Dancila; Committee Member: Juan R. Cruz; Committee Member: Massimo Ruzzene; Committee Member: Rami Haj-Ali
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Morishima, Ryoko. "Analysis of composite wing structures with a morphing leading edge." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/6797.
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One of the main challenges for the civil aviation industry is the reduction of its environmental impact. Over the past years, improvements in performance efficiency have been achieved by simplifying the design of the structural components and using composite materials to reduce the overall weight. These approaches however, are not sufficient to meet the current demanding requirements set for a „greener‟ aircraft.
Significant changes in drag reduction and fuel consumption can be obtained by using new technologies, such as smart morphing structures. These concepts will in fact help flow laminarisation, which will increase the lift to drag ratio. Furthermore, the capability to adapt the wing shape will enable to optimise the aerodynamic performance not only for a single flight condition but during the entire mission. This will significantly improve the aircraft efficiency.
The current research work has been carried out as part of the European Commission founded Seventh Framework Program called „Smart High Lift Device for the Next Generation Wing‟ (SADE), which main aim is to develop and study morphing high lift devices. The author‟s investigation focused on developing a design concept for the actuation mechanism of a morphing leading edge device. A detailed structural analysis has been carried out in order to demonstrate its feasibility.In the first phase of the research the attention was directed on the preliminary design and analysis of the composite wing box. The parameters of the key structural components, such as skin, spars, ribs and stringers were set to satisfy the static stress and buckling requirements. Moreover, numerical and experimental studies were conducted to analyse the static failure and buckling behaviour of two typical composite wing structural components: a spar section and a web and base joint assembly.
In the second stage of the research, a design for the morphing leading edge actuation mechanism was developed. The actuation system was designed in such a way that the target shape was reached with minimum actuation force demand. A geometrical nonlinear FE analysis was conducted to simulate the leading edge morphing deflection and ensure that structural strength requirements were satisfied. Furthermore, the behaviour of the skin integrated with the internal actuation mechanism was modelled under the aerodynamic pressure, at different flight conditions and gust loads, in order to prove that the proposed actuation system can compete with the conventional rigid rib.
This study demonstrated that a feasible morphing leading edge design for a next generation large aircraft wing can be achieved. Developing the readiness of this technology will have a significant impact on aircraft efficiency and considerable contribution towards a more environmental friendly aviation.
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Lachenal, Xavier. "Concepts for morphing composite structures using non-linear stiffness tailoring." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601215.
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Recently, morphing structures have found increased interest due to their potential for combining conflicting requirements of strength, flexibility and low mass. Many concepts depend on continuously powered actuators to deform the structure. Others possess multiple stable states, i.e. multi-stability and power is only needed to change the shape, not to hold it. This dissertation explores the design space of a helical morphing, composite, twisting structure capable of large deformations along its axis of twist with non-linear stiffness properties. Multi-stability is achieved by a combination of pre-stress, geometry of the structure and material properties. Multi-stability is fully exploited by demonstrating the capability of the helix to be bi-stable or, depending on the design parameters, to hold any twisted configuration; hence presenting the remarkable property of zero torsional stiffness. Three proof-of-concept case studies are detailed: simple helices, a wind turbine twisting tip and a bi-stable I-beam. In the first instance, the helical structure is investigated and analytically modelled. Prototypes are developed to verify the non-linear stiffness properties of the structure and experimental results are correlated against analytical and finite element model data. Three different stability characteristics are explored and detailed. Multi-stability is analysed using a simple analytical model, predicting the positions of stable and unstable states for different design parameters and material properties. Actuation using piezoelectric material is also explored in a separate analytical study. Then, the negative stiffness property of the pre-stressed structure is incorporated into a half-scale twisting wind turbine blade. Overall, the manufactured blade achieves zero stiffness in torsion for angles of twist between _5° to +5° due to the added helical structure. Finally, a common structural component, the I-beam, is redesigned to show bi-stability.
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Dlisani, Mbulelo Patrick. "Development of Aero Morphing reinforced composite materials embedded with NiTi alloys." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1258.
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Thesis ( MTech(Mechanical Engineering))--Cape Peninsula University of Technology, 2011This study deals with the development of aero morphing reinforced composite materials embedded with NiTi alloys. It is shown that the composite materials can be manufactured using resin infusion process to produce better mechanical properties such as tensile strength and material stiffness. These composite materials are modelled experimentally using temperature and time parameters. The object of the modelling is to determine the effect of process temperature on the smart material alloy (SMA). As a result, a composite structural designer would now possess an added dimension in optimising material design. In addition, the study is conducted to analyse the structural behaviour of composite materials when embedded and when not embedded with NiTi alloys. The analysis is constrained to the evaluation of material tensile strength and stiffness upon performance of composite structures. A macro mechanical approach is employed to perform the analysis in specimens with different fibre orientation [0°, 45° and 90°]. The estimation of tensile strength and stiffness parameters is based on the characteristics obtained from a macro mechanical approach. The orientation which posses the best material properties is selected to embed NiTi alloys. The experimental results of unembedded specimens are validated with the application of micromechanics equations and an Ansys software finite element modelling tool. There is fair agreement between the finite element simulation of macro mechanical test of the specimens and the measured experimental results. Although the macro mechanical approach is found to be successful, it is imperative to characterise the material interface strength of embedded specimens using a pull out test. The pullout test showed to some great extent the properties of reinforced composite embedded with NiTi alloys.
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Dayyani, Iman. "Mechanical behavior of composite corrugated structures for skin of morphing aircraft." Thesis, Swansea University, 2015. https://cronfa.swan.ac.uk/Record/cronfa42865.
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Corrugated panels have gained considerable popularity in a range of engineering applications, particularly in morphing skin applications due to their remarkable anisotropic characteristics. They are stiff to withstand the aerodynamic loads and flexible to enable the morphing deformations. In this thesis a detailed review of the literature on corrugated structures is presented. The specific characteristics of corrugated structures such as: high anisotropic behaviour, high stiffness and good durability, lightness and cost effectiveness are discussed comprehensively. However for the application in morphing aircraft, the optimal design of the corrugated panels requires simple models of these structures to be incorporated into multi-disciplinary system models. Therefore equivalent structural models are required that retain the dependence on the geometric parameters and material properties of the corrugated panels. In this regard, two analytical solutions based on homogenization and super element techniques are presented to calculate the equivalent mechanical properties of the corrugated skin. Different experimental and numerical models are investigated to verify the accuracy and efficiency of the presented equivalent models. The parametric studies of different corrugation shapes demonstrate the suitability of the proposed super element for application in further detailed design investigations. Then the design and multi-objective optimization of an elastomer coated composite corrugated skin for the camber morphing aerofoil is presented. The geometric parameters of the corrugated skin are optimized to minimize the in-plane stiffness and the weight of the skin and to maximize the flexural out-of-plane stiffness of the corrugated skin. A finite element code for thin beam elements is used with the aggregate Newton's method to optimize the geometric parameters of the coated corrugated panel. The advantages of the corrugated skin over the elastomer skin for the camber morphing structure are discussed. Moreover, a finite element simulation of the camber morphing internal structure with the corrugated skin is performed under typical aerodynamic and structural loadings to check the design approach.
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Gustafson, Eric Andrew. "Design, Simulation, and Wind Tunnel Verication of a Morphing Airfoil." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/33663.
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The application of smart materials to control the flight dynamics of a Micro Air Vehicle
(MAV) has numerous benefits over traditional servomechanisms. Under study is wing morphing achieved through the use of piezoelectric Macro Fiber Composites (MFCs). These devices exhibit low power draw but excellent bandwidth characteristics. This thesis provides a background in the 2D analytical and computer modeling tools and methods needed to design and characterize an MFC-actuated airfoil.
A composite airfoil is designed with embedded MFCs in a bimorph configuration. The deflection capabilities under actuation are predicted with the commercial finite element package NX Nastran. Placement of the piezoelectric actuator is studied for optimal effectiveness. A thermal analogy is used to represent piezoelectric strain. Lift and drag coefficients in low Reynolds number flow are explored with XFOIL. Predictions are made on static aeroelastic effects. The thin, cambered Generic Micro Aerial Vehicle (GenMAV) airfoil is fabricated with a bimorph actuator. Experimental data are taken with and without aerodynamic loading to validate the computer model. This is accomplished with in-house 2D wind tunnel testing.Master of Science
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Hinshaw, Tyler. "Analysis and Design of a Morphing Wing Tip using Multicellular Flexible Matrix Composite Adaptive Skins." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/33932.
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The material presented in this thesis uses concepts of the finite element and doublet panel methods to develop a structural-aerodynamic coupled mathematical model for the analysis of a morphing wing tip composed of smart materials. Much research is currently being performed within many facets of engineering on the use of smart or intelligent materials. Examples of the beneficial characteristics of smart materials might include altering a structureâ s mechanical properties, controlling its dynamic response(s) and sensing flaws that might progressively become detrimental to the structure. This thesis describes a bio-inspired adaptive structure that will be used in morphing an aircraftâ s wing tip. The actuation system is derived from individual flexible matrix composite tube actuators embedded in a matrix medium that when pressurized, radical structural shape change is possible.
A driving force behind this research, as with any morphing wing related studies, is to expand the limitations of an aircraftâ s mission, usually constrained by the wing design. Rather than deploying current methods of achieving certain flight characteristics, changing the shape of a wing greatly increases the flight envelope. This thesis gives some insight as to the structural capability and limitations using current numerical methods to model a morphing wing in a flow.Master of Science
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Marcantoni, Matteo. "Design and development of a morphing wing trailing edge." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Modern aircraft rely on mechanical actuators and hydraulic systems to move flaps and slats that allow an increase of lift at low speed.
Although these systems are reliable and really efficient, gaps in between the extendable parts of flaps create lots of noise. Moreover, the conventional actuation system is quite complex due to the need for oleo-dynamic cylinders (or electrical actuators), hinges, leverages, slides.
Furthermore, these devices have discrete displacement of motion (in terms of angle) and they can be used during take-off and landing phases only due to the high dynamic pressure during the cruise phase.
The aim of this project is to find an alternative to conventional flaps creating a morphing trailing edge.
The rear part of the wing performs the same job as classic flaps but in this work the feasibility of a change in technology is addressed: a new way to obtain a change in airfoil camber can be achieved without discontinuities on the surface by introducing the concept of morphing wing. Removing the gaps between the movable and fixed surfaces will reduce significantly the noise both for passenger comfort and environmental issue. Furthermore, an increase in aerodynamic efficiency and a reduction of weight - which in turn lead to savings in terms of fuel - as well as an increase in reliability due to the need to use less parts have to be investigated in the future to better understand pros and cons of the morphing wing concept.
The morphing trailing edge could be divided into separate sections along the wing span in order to have a behavior similar to a set of single actuated mechanisms (controlled independently) with no constraints in displacements so that small changes can be applied during cruise condition to change the twist of the wing and aerodynamic performances depending on the attitude and speed.
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Puttmann, John Paul. "Spatially Targeted Activation of a SMP." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1525166147319011.
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Doepke, Edward Brady. "Design Demonstration and Optimization of a Morphing Aircraft Control Surface Using Flexible Matrix Composite Actuators." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82494.
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The morphing of aircraft wings for flight control started as a necessity for the Wright Brothers but quickly fell out of favor as aircraft increased speed. Currently morphing aircraft control is one of many ideas being explored as we seek to improve aircraft efficiency, reduce noise, and other alternative aircraft solutions. The conventional hinged control surface took over as the predominant method for control due to its simplicity and allowing stiffer wings to be built. With modern technologies in variable stiffness materials, actuators, and design methods, a morphing control surface, which considers deforming a significant portion of the wing's surface continuously, can be considered.
While many have considered morphing designs on the scale of small and medium size UAVs, few look at it for full-size commercial transport aircraft. One promising technology in this field is the flexible matrix composite (FMC) actuator. This muscle-like actuator can be embedded with the deformable structure and unlike many other actuators continue to actuate with the morphing of the structure. This was demonstrated in the FMC active spoiler prototype, which was a full-scale benchtop prototype, demonstrated to perform under closed-loop control for both the required deflection and load cases.
Based on this FMC active spoiler concept a morphing aileron design was examined. To do this an analysis coupling the structure, fluid, and FMC actuator models was created. This allows for optimization of the design with the objectives of minimizing the hydraulic energy required and mass of the system by varying the layout of the FMC aileron, the material properties used, and the actuator's design and placement with the morphing section.
Based on a commercial transport aircraft a design case was developed to investigate the optimal design of a morphing aileron using the developed analysis tool. The optimization looked at minimizing the mass and energy requirements of the morphing aileron and was subject to a series of constraints developed from the design case and the physical limitations of the system. A Pareto front was developed for these two objectives and the resulting designs along the Pareto front explored. From this optimization, a series of design guidelines were developed.Ph. D.
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Bilgen, Onur. "Macro Fiber Composite Actuated Unmanned Air Vehicles: Design, Development, and Testing." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33117.
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The design and implementation of a morphing unmanned aircraft using smart materials is presented. Articulated lifting surfaces and articulated wing sections actuated by servos are difficult to instrument and fabricate in a repeatable fashion on thin, composite-wing micro-air-vehicles. Assembly is complex and time consuming. A type of piezoceramic composite actuator commonly known as Macro Fiber Composite (MFC) is used for wing morphing. The actuation capability of this actuator on fiberglass unimorph was modeled by the Rayleigh-Ritz method and quantified by experimentation. Wind tunnel tests were performed to compare conventional trailing edge control surface effectiveness to an MFC actuated wing section. The continuous surface of the MFC actuated composite airfoil produced lower drag and wider actuation bandwidth. The MFC actuators were implemented on a 0.76 m wingspan aircraft. The remotely piloted experimental vehicle was flown using two MFC patches in an elevator/aileron (elevon) configuration. Preliminary testing has proven the stability and control of the design. Flight tests were performed to quantify roll control using the actuators. Force and moment coefficients were measured in a low-speed, open section wind tunnel, and the database of aerodynamic derivatives were used to analyze control response.Master of Science
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Stiltner, Brandon Chase. "Macro Fiber Composite Actuated Control Surfaces with Applications Toward Ducted Fan Vehicles." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/34441.
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In most man-made flight, vehicle control is achieved by deflecting flaps. However, in nature, morphing surfaces are found on both flying and swimming creatures. Morphing is used in nature because it is a more efficient form of control. This thesis investigates using morphing flaps to control a class of UAVs known as ducted fan vehicles. Specifically, this thesis discusses both the challenges and benefits of using morphing control surfaces.
To achieve morphing, a piezoelectric device known as Macro Fiber Composites is used. These devices are embedded in the skin of the vehicles control surface, and when actuated, they cause the control surface to increase or decrease camber. This thesis describes experiments that were performed to investigate the performance of this type of actuator. Specifically, the actuation bandwidth of these devices is presented and compared to a servo. Results show that the morphing control surfaces can actuate at frequencies twice as high as a servo.
Master of Science
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Lang, Jr Joseph Reagle. "Characterization of Oscillatory Lift in MFC Airfoils." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50935.
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The purpose of this research is to characterize the response of an airfoil with an oscillatory morphing, Macro-fiber composite (MFC) trailing edge. Correlation of the airfoil lift with the oscillatory input is presented. Modal analysis of the test airfoil and apparatus is used to determine the frequency response function. The effects of static MFC inputs on the FRF are presented and compared to the unactuated airfoil.
The transfer function is then used to determine the lift component due to cambering and extract the inertial components from oscillating airfoil. Finally, empirical wind tunnel data is modeled and used to simulate the deflection of airfoil surfaces during dynamic testing conditions. This research serves to combine modal analysis, empirical modeling, and aerodynamic testing of MFC driven, oscillating lift to formulate a model of a dynamic, loaded morphing airfoil.Master of Science
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Schultz, Marc Robert. "Use of Piezoelectric Actuators to Effect Snap-Through Behavior of Unsymmetric Composite Laminates." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27086.
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As a new concept for morphing structures, the use of piezoelectric actuators to effect snap-through behavior of simple unsymmetric cross-ply composite laminates is examined. Many unsymmetric laminates have more than one stable room-temperature shape and can be snapped through from one stable shape to another. In this new concept for morphing structures, one or more piezoelectric actuators are bonded to unsymmetric laminates, and are then used to snap the laminate from one shape to another. The actuator would be used to change shape, but would not be required to maintain the shape. Using the Rayleigh-Ritz technique, several models are developed to predict the interaction between the base laminate and the actuator. In particular, the voltage (applied to the actuator) needed to snap the laminate is predicted. The NASA-LaRC Macro-Fiber Composite&174; (MFC&174;) actuator is chosen as the actuator of choice for this work. A laminate is manufactured, an actuator is bonded to the laminate, and experiments are performed. Since the agreement between the initial models and experimental results was not good, the models were revised. Good agreement between the predictions of the revised model and experiment is reached. Suggestions for future research directions are presented.Ph. D.
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Pecorella, Daniele. "Methodology for the design and optimization of a morphing wing droop-nose structure for greener aircraft." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
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Droop-Nose Leading Edge (DNLE) morphing wings are one of the most promising devices in order to achieve aerodynamic drag and noise reduction during take-off and landing phases. An accurate design of these structures could lead to the decrease of aircraft fuel consumption in the perspective of reaching a greener aviation, following the objectives indicated by Flightpath 2050 issued by the E.U. However, due to the challenges related to the realization of this technology and TRL reached, DNLE are more likely implemented in Unmanned Aerial Systems (UAS) for testing and evaluation purposes. In the present study, an optimization methodology for the DNLE composite laminate skin and morphing mechanism structure is proposed and applied to a study case represented by the UAS-S45 aircraft. The work starts from the morphing leading edge structure developed by the LARCASE laboratory at ETS Montreal. The results showed that by means of the optimization strategy adopted, the force required on the actuator mechanism is 88% lower than the original design. A significant improvement on the profile smoothness along its section and in the spanwise direction in morphing conditions has been obtained too. However, further investigations are still needed in order to achieve a more appropriate morphing shape. Despite this, it appears from the results obtained that the proposed methodology can be useful to tackle the DNLE design problem in an effective and efficient way. What developed in this work has been conceived to support the investigation of DNLE in the small leading edge profiles typical of the UAS. In this way, an easier procedure for the set up of the design flow, and a decrease in the computational effort for the optimization process can be obtained. An experimental validation of the results obtained is currently being performed at ETS, and future development regards the assessment of the errors of the numeric procedure herein presented respect to real data.
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Elwell, Roston Clement. "Miniature Hourglass Shaped Actuator Geometry Study Using A Finite Element Simulation." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7711.
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This project investigated a miniature, hourglass-shaped actuator (MHA) and how its geometry affects performance. A custom, self-contained, finite-element simulation code predicts how each MHA deforms when pressurized internally.
This analysis describes the MHA geometry's effects on four characteristics: a) work density b) mechanical advantage, c) work advantage and d) percent elongation. The first three characteristics are compared to a traditional actuator operating at the same pressure and elongation.
A finite-element modeling code was tailored to study the MHA at 5 MPa internal pressure when 1) MHA height and side-wall thickness are constant and side-wall arc length varies; 2) MHA side-wall arc length and thickness are constant and the height varies; and 3) MHA side-wall thickness varies while height and side-wall arc length are fixed. Case 3 was studied using the MHA geometry with the highest work density found in either condition 1 or 2.
Peak mechanical advantage, 6.47, occurs in a constant height MHA-Case 1-when the side-wall arc length is shortest. Highest elongation, 8.67%, occurs in the Case 1 MHA with the longest side-wall arc length. Finally, under Case 3, work density reaches 0.434 MJ/m3 when the side-wall thickness is 1.9 mm.
The MHA has potential for active structures because its work density is high-higher than traditional actuators with the same elongation. Their small elongations limit their use; however, much work remains to determine how MHAs might be arranged in a useful array. Never the less, morphing airfoils and other active structures might benefit from embedded MHAs.