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Objectives: To assess factors affecting Saudi population preference in losing weight either by bariatric surgeries or by conservative strategies. Methods: A cross sectional study was done using a self-administered questionnaire distributed online. Study was done on 518 participants (group 1) who did not prefer to undergo bariatric surgery and preferred conservative strategies in weight reduction and group 2 (84 participants) who preferred to undergo bariatric surgery. Results: Participants in group 1 and group 2 represented 86% and 14% of the sample. Group II had a significant higher percent of obese and per-obese individuals, who usually eat basic meals every day, who usually have soft drinks as beverages, who eat fast food for more than 2 times weekly, who had more than 6 attempts to lose weight in the last 5 years and who thought that their families would support their efforts in improving their food habits. Group II had a statistically significant higher percent of those who consider bariatric surgery as an effective tool for weight loss, who believed that they would lose more weight with bariatric surgery, and who believe that surgery will cause a drastic change in their lifestyle. Group 1 had a significant higher percent of those who eat fruit and vegetables every day, who reported always practicing physical activity during the entire year. Conclusion: Factors affecting the preference of weight loss were eating habits, physical activity, and attempt of dieting. An efficient health education programs about bariatric surgeries is needed to correct misconceptions regarding the surgery.

This paper studies the influence of flared-hinge folding wingtips on the aerodynamic derivatives and flight dynamics of a narrow-body transport aircraft. In addition, the influence of fold angle, h...

This paper presents the development of a novel compliant polymorphing wing capable of chord and camber morphing for small UAVs. The morphing wing can achieve up to 10% chord extension and ±20° camber changes. The design, modelling, sizing, manufacturing and mechanical testing of the wing are detailed. The polymorphing wing consists of one continuous front spar fixed to the fuselage and a rear spar on each side of the wing. Each rear spar can translate in the chordwise direction (chord morphing) and rotate around itself (camber morphing). A flexible elastomeric latex sheet is used as the skin to cover the wing and maintain its aerodynamic shape whilst allowing morphing. The loads from the skin are transferred to the spars using the compliant cellular ribs that support the flexible skin and facilitate morphing. Pre-tensioning is applied to the skin to minimize wrinkling when subject to aerodynamic and actuation loads. A rack and pinion actuation system, powered by stepper motors, is used for morphing. Aero-structural design, analysis and sizing are conducted. Performance comparison between the polymorphing wing and the baseline wing (non-morphing) shows that chord morphing improves aerodynamic efficiency at low angles of attack while camber morphing improves efficiency at high angles of attack.

This paper presents a parametric study on the aeroelasticity of cantilever wings equipped with Flared Hinge Folding Wingtips (FHFWTs). The finite element method is utilized to develop a computational, low-fidelity aeroelastic model. The wing structure is modelled using Euler–Bernoulli beam elements, and unsteady Theodorsen’s aerodynamic strip Theory is used for aerodynamic load predictions. The PK method is used to estimate the aeroelastic boundaries. The model is validated using three rectangular, cantilever wings whose properties are available in literature. Then, a rectangular, cantilever wing is used to study the effect of folding wingtips on the aeroelastic response and stability boundaries. Two scenarios are considered for the aeroelastic analysis. In the first scenario, the baseline, rectangular wing is split into inboard and outboard segments connected by a flared hinge that allows the outboard segment to fold. In the second scenario, a folding wingtip is added to the baseline wing. For both scenarios, the influence of fold angle, hinge-line angle (flare angle), hinge stiffness, tip mass and geometry are assessed. In addition, the load alleviation capability of FHFWT is evaluated when the wing encounters discrete (1-cosine) gusts. Finally, the hinge is assumed to exhibit cubic nonlinear behavior in torsion, and the effect of nonlinearity on the aeroelastic response is assessed and analyzed for three different cases.

This paper investigates the effectiveness of a resonance avoidance concept for composite rotor blades featuring extension&ndash, twist elastic coupling. The concept uses a tendon, attached to the tip of the blade, to apply a proper amount of compressive force to tune the vibration behavior of the blade actively. The tendon is simulated by applying a non-conservative axial compressive force applied to the blade tip. The main load carrying part of the structure is the composite spar box, which has an antisymmetric layup configuration. The nonlinear dynamic behavior of the composite blade is modelled by using the geometrically exact fully intrinsic beam equations. The resulting nonlinear differential equations are discretized using a time&ndash, space scheme, and the stationary and rotating frequencies of the blade are obtained. It is observed that the proposed resonance avoidance mechanism is effective for tuning the vibration behavior of composite blades. The applied compressive force can shift the frequencies and the location at which the frequency veering take place. Furthermore, the compressive force can also cause the composite blade to get unstable depending on the layup ply angle. Finally, the results, highlighting the importance of compressive force and ply angle on the dynamic behavior of composite blades, are presented and discussed.

A morphing aircraft continuously adjusts its wing geometry to achieve optimal flight characteristics for a wide range of flight conditions. Research on morphing aircraft has focused on developing wings with 1 morphing degree of freedom “monomorphing”. However, nowadays the focus is on developing wings with multiple morphing degrees of freedom “polymorphing”. One of the key design challenges for morphing aircraft technology is the development of skin capable of facilitating morphing whilst maintaining the aerodynamic shape of the wing. Soft polymeric materials represent a potential candidate to act as morphing skin because of their ability to undergo large deformation in multiaxial directions. In this study, latex skin is characterized under all possible deformation modes such as uniaxial, pure shear, biaxial, and equibiaxial to account for monomorphing and polymorphing applications. The effects of strain rate, thickness, and aspect ratio on hysteresis loss, stress relaxation and, stiffness are also studied. The outcomes of this study provide a comprehensive understanding of the mechanical viscoelastic behavior of latex skin under various deformation modes.

This paper studies the aeroelastic behavior of telescopic, multi-segment, span morphing wings. The wing is modeled as a linear, multi-segment, stepped, cantilever Euler–Bernoulli beam. It consists of three segments along the axis and each segment has different geometric, mechanical, and inertial properties. The aeroelastic analysis takes into account spanwise out-of-plane bending and torsion only, for which the corresponding shape functions are derived and validated. The use of shape functions allows representing the wing as an equivalent aerofoil whose generalized coordinates are defined at the wingtip according to the Rayleigh–Ritz method. Theodorsen’s unsteady aerodynamic theory is used to estimate the aerodynamic loads. A representative Padé approximation for the Theodorsen’s transfer function is utilized to model the aerodynamic behaviors in state-space form allowing time-domain simulation and analysis. The effect of the segments’ mechanical, geometric, and inertial properties on the aeroelastic behavior of the wing is assessed. Finally, the viability of span morphing as a flutter suppression device is studied.

In this paper we propose a homogenisation-based four-scale model for the mechanical properties of cross-laminated timber. The spatial scales considered in this study are the wood cell-wall, the wood fibres, growth rings and the structural scale. The computational homogenisation scheme is solved sequently from the lowest to the highest level in order to determine the effective mechanical properties of each material scale. As we are interested in improving the predictions of our computational simulations, we propose an optimisation strategy to calibrate the micro-mechanical parameters. Our numerical predictions are compared with experimental results and are validated successfully.

Rigid wings usually fly at sub-optimal conditions generating unnecessary aerodynamic loses represented in flight time, fuel consumption, and unfavourable operational characteristics. High aspect ratio wings have good range and fuel efficiency, but lack manoeuvrability. On the other hand, low aspect ratio wings fly faster and are more manoeuvrable, but have poor aerodynamic performance. Span morphing technology allows integrating both features in a single wing design and allows continuously adjusting the wingspan to match the instantaneous flight conditions and mission objectives. This paper develops, a novel span morphing concept, the Gear driveN Autonomous Twin Spar (GNATSpar) for a mini-UAV. The GNATSpar can be used to achieve span extensions up to 100% but for demonstration purposes it is used here to achieve span extensions up to 20% to reduce induced drag and increase flight endurance. The GNATSpar is superior to conventional telescopic and articulated structures as it uses the space available in the opposite sides of the wing instead of relying on overlapping structures and bearings. In addition, it has a self-locking actuation mechanism due to the low lead angle of the driving worm gear. Following the preliminary aero-structural sizing of the concept, a physical prototype is developed and tested in the 7 ′ × 5 ′ wind-tunnel at the University of Southampton. Finally, benefits and drawbacks of the design are highlighted and analysed.

This paper presents the development and extensive testing of the Transformer aircraft, a multimission UAV capable of symmetric and asymmetric span morphing. The UAV utilises a novel actuation system based on a rack and pinion mechanism to achieve span extensions up to 50%. The Transformer can morph symmetrically to enhance flight performance and asymmetrically to provide roll control. Extensive mechanical testing followed by wind-tunnel testing in the RJ Mitchell Wind-tunnel at the University of Southampton were conducted to ensure structural integrity and assess the behaviour of the UAV. Finally, a series of flight-testing were performed and the flight mechanics aspects associated with both symmetric and asymmetric span morphing were investigated.

A low-fidelity aeroelastic model is developed to study the dynamic behaviour of uniform, cantilever span morphing wings. The wing structure is modelled using the shape functions of the bending and torsional modes of a uniform cantilever wing according to the Rayleigh–Ritz method. Theodorsen's unsteady aerodynamic theory is used to model the aerodynamic loads. A Pade approximation for the Theodorsen's transfer function is utilised to allow time-domain simulation and analysis. The sensitivity of the aeroelastic behaviour of span morphing wings to different geometric parameters and mechanical properties is considered. Furthermore, the impact of morphing rate on the aeroelastic behaviour is studied. Finally, the use of two novel span morphing concepts for flutter suppression is assessed.

This paper presents the optimum design of a PID controller for the Adaptive Torsion Wing (ATW) using the genetic algorithm (GA) optimiser. The ATW is a thin-wall, two-spar wingbox whose torsional stiffness can be adjusted by translating the spar webs in the chordwise direction inward and towards each. The reduction in torsional stiffness allows external aerodynamic loads to deform the wing and maintain its shape. The ATW is integrated within the wing of a representative UAV to replace conventional ailerons and provide roll control. The ATW is modelled as a two-dimensional equivalent aerofoil using bending and torsion shape functions to express the equations of motion in terms of the twist angle and plunge displacement at the wingtip. The full equations of motion for the ATW equivalent aerofoil were derived using Lagrangian mechanics. The aerodynamic lift and moment acting on the aerofoil were modelled using Theodorsen’s unsteady aerodynamic theory. The equations of motion are then linearised around an equilibrium position and the GA is employed to design a PID controller for the linearised system to minimise the actuation power require. Finally, the sizing and selection of a suitable actuator is performed.

In this paper we investigate the mechanical behaviour of cross-laminated timber panels by a computational homogenisation approach. A finite element procedure is adopted within a multi-scale modelling framework to determine the constitutive response of timber. As some of the microstructural parameters of wood are either not well-known or susceptible to considerable variation, we introduce uncertainty in the definition of the material. In order to validate the present multi-scale model, we measure experimentally the longitudinal Young’s modulus and density of sawn wood beams made of radiata pine. In addition, we carry out several experimental tests on cross-laminated timber panels subject to bending, shear and compression loads. Our numerical predictions are compared with the experiments and are validated successfully, revealing the potential predictive capabilities of the present multi-scale modelling for the analysis of wood materials and timber structures.

This paper investigates the extensibility of the wood cell-wall composite in the presence of parametric uncertainty by means of a multi-scale finite element approach. Normally, the three fundamental phases in wood, that is, cellulose, lignin and hemicellulose, present considerable scatter in their microstructure and mechanical properties. Nevertheless, by considering uncertainty in their properties, a significant computational cost is added to the solution of a large set of realisations represented by expensive fully-coupled multi-scale analyses. In order to tackle this high cost, we build a statistical approximation to the output of the computer model. Following this strategy, several micromechanical parameters are perturbed to study their influence on the extensibility of the material under tensile loading conditions. By reducing the cost of performing uncertainty analysis of the homogenised mechanical response, we are able to estimate the 5-th, 50-th, and 95-th percentile of the ultimate tensile strains of the material. We contrast our numerical predictions with experimental data, finding a good agreement for a wide range of initial microfibril angles.

Background: Fractures of acrylic resin dentures are a common occurrence in clinical dentistry. The denture may be fractured accidentally when dropped or while in service in the mouth due to flexural fatigue. Objectives: The aim of this study was to compare the elastic modulus and the flexural strength between two heat-cured acrylic resins used in denture bases: a high-impact resin (Lucitone 199) and a traditional resin (Rodex). Materials and methods: Rectangular strips of Lucitone 199 and Rodex (10 samples each) were fabricated and stored in artificial saliva at 37 °C for 2 weeks. The specimens were subjected to a three-point flexural test. The data were statistically analysed with Student’s t-test (p ⩽ .05). Results: The high-impact acrylic resin had a lower elastic modulus (p = .000) and higher flexural strength (p = .001) compared to the traditional acrylic resin. Conclusion: Within the limitations of this study, it can be concluded that the high-impact acrylic resin is a suitable denture base material for patients with clinical fracture of the acrylic denture. Keywords: Denture, Acrylic resin, Fracture, High-impact, Elastic modulus, Flexural strength

This note assesses the benefits of active aeroelastic structures (AAS) in enhancing flight performance and control authority. A representative AAS concept, whose torsional stiffness and shear centre position can be altered depending on the instantaneous flight condition, is employed in the wing of a medium altitude long endurance (MALE) UAV. A multidisciplinary design optimisation (MDO) suite is used in this study. It turns out that AAS can be very effective when used for enhancing control authority of the vehicle but have limited benefits in terms of flight performance (lift to drag).

This paper presents an overview of an advanced, conceptual wing-box weight estimation and sizing model for transport aircraft. The model is based on linear thin-walled beam theory, where the wing-box is modelled as a simple, swept tapered multi-element beam. It consists of three coupled modules, namely sizing, aeroelastic analysis, and weight prediction. The sizing module performs generic wing-box sizing using a multi-element strategy. Three design cases are considered for each wing-box element. The aeroelastic analysis module accounts for static aeroelastic requirements and estimates their impact on the wing-box sizing. The weight prediction module estimates the wing-box weight based on the sizing process, including static aeroelastic requirements. The breakdown of the models into modules increases its flexibility for future enhancements to cover complex wing geometries and advanced aerospace materials. The model has been validated using five different transport aircraft. It has shown to be sufficiently robust, yielding an error bandwidth of ±3%, an average error estimate of -0·2%, and a standard error estimate of 1·5%.

This paper assesses the feasibility of the Adaptive Torsion Wing (ATW) concept to replace conventional ailerons and enhance the manoeuvrability of a MALE UAV. The ATW concept is a thin-walled closed section two-spar wingbox whose torsional stiffness can be adjusted through the chord-wise position of the front and rear spar webs. The reduction in torsional stiffness allows external aerodynamic loads to induce aeroelastic twist that can be used as a function of the flight conditions to obtain a desired roll control authority. Modelling of the concept was performed using a conceptual design tool developed in MATLABTM. The variation of structural figures of merit are evaluated and discussed. Finally, an MDO study was performed to have in-depth assessments of the potential benefits of the ATW in replacing ailerons and providing sufficient roll control.

This paper proposes a novel framework for classification of morphing technology based on its functionality, operation, and the structural layout. In addition, it highlights the limitations of the conventional design approach to exploit the benefits of the technology using representative examples and results.

This paper presents the Adaptive Torsion Wing (ATW) concept and performs two multidisciplinary design optimisation (MDO) studies by employing this novel concept across the wing of a representative UAV. The ATW concept varies the torsional stiffness of a two-spar wingbox by changing the enclosed area through the relative chordwise positions of the front and rear spar webs. The first study investigates the use of the ATW concept to improve the aerodynamic efficiency (lift-to-drag ratio) of the UAV. In contrast, the second study investigates the use of the concept to replace conventional ailerons and provide roll control. In both studies, the semi-span of the wing is split into five equal partitions and the concept is employed in each of them. The partitions are connected through thick ribs that allow the spar webs of each partition to translate independently of the webs of adjacent partitions and maintain a continuous load path across the wing span. An MDO suite consisting of a Genetic Algorithm (GA) optimiser coupled with a high-end low-fidelity aero-structural model was developed and employed in this paper.

This paper presents a methodology that permits accounting for acoustic fatigue effects when sizing safe-life structural skin-stringer panels at the conceptual design stage of aircraft product development. The approach is based upon estimation of the maximum noise radiated from an entry-into-service year 2020 turbofan. Sonic fatigue endurance is assessed for different skin-stringer panels having different values of skin thickness, rib pitch and stringer pitch. Three different materials were considered in this study: aluminium 2024-T3 alloys (Al 2024-T3); carbon fibre-reinforced plastics (CFRP); and, glass reinforced fibre metal laminate (Hybrid Glare-3). The study resulted in CFRP having the most favourable sonic fatigue performance. In order to link economic considerations into technical decision making, the sonic endurance methods were coupled with an industry grade costing analysis tool (SEER-HTM) to examine the impact of safe-life design on the panel cost and weight. The presented methodology has been shown to be sufficiently generic in nature and robust. This will not only assist in identifying acoustic fatigue as a potential critical design scenario, but will also increase throughput during conceptual design sizing and optimisation.

This paper presents the variable cross section spar (VCSpar) concept that facilitates varying the shear center position relative to the aerodynamic center, allowing the external aerodynamic loads to twist the structure and maintain its deformed shape. The VCSpar is considered in this paper as integrated within the wing of a representative unmanned aerial vehicle (UAV) to enhance its flight performance and control authority. A preliminary design study was conducted to assess the potential benefits of the concept using a low-fidelity design tool. Then, aeroelastic modeling of the concept was performed where the VCSpar was modeled as a two-dimensional equivalent aerofoil using bending and torsion shape functions to express the equations of motion in terms of the twist angle and plunge displacement at the wingtip. The aerodynamic lift and moment acting on the equivalent aerofoil were modeled using Theodorsen’s unsteady aerodynamic theory. A low-dimensional state-space representation of an empirical Theodorsen’s transfer function was adopted to allow time-domain analyses.

This paper presents an experimental investigation on using FOLDing wingtips sERving as cONtrol effectorS (FOLDERONS) for a mini Unmanned Aerial Vehicle (UAV). A representative off-the-shelf mini-UAV with a conventional configuration was selected. The main theme of this paper is to utilise FOLDERONS as a control effector (mainly in roll) to augment the control authority of conventional control surfaces. Furthermore, the impact of actuation rate on the effectiveness of FOLDERONS is assessed. The paper describes the preliminary and detailed design and sizing of the morphing wing. In addition, the manufacturing of the wing system and its integration with the UAV are addressed. Wind-tunnel testing in the RJ Mitchell wind-tunnel at the University of Southampton was performed. Both static (straight and sideslip) and dynamic (straight flight) tests are conducted at a range of airspeeds and Angles Of Attack (AOAs). The impact of folding wingtips on the lateral and directional stability is analysed. The main finding of this paper is that FOLDERONS are effective (especially at large dynamic pressure and AOAs) in controlling the lateral and directional stability. Finally, this study shows that FOLDERONS cannot fully replace conventional ailerons especially at low dynamic pressures, and their strong dependence on the AOA makes them prone to a roll reversal phenomena when the wing (and FOLDERONS) is operating at negative AOAs.

This paper develops and models the Compliant Spar concept that allows the wing span to be varied to provide roll control and enhance the operational performance for a medium altitude long endurance (MALE) UAV. The wing semi-span is split into morphing partitions and the concept maybe incorporated in each partition; however only the tip partition is considered here. The Compliant Spar is made of compliant joints arrange in series to allow the partition to be flexible under axial (spanwise) loads but at the same time stiff enough to resist bending loads. Each compliant joint consists of two concentric overlapping AL 2024-T3 tubes joined together using elastomeric material. Under axial (spanwise) loading, the elastomeric material deforms in shear allowing the overlapping distance between the tubes to vary and hence the length (in the spanwise direction) of the joint/spar to vary. High fidelity modelling of the concept is performed. Then, structural optimisation studies are performed to minimise the axial stiffness and the structural mass of the concept for various design constraints. The flexible skin and actuation system to be used are also addressed.

Aircraft designed to fly a wide mission range will have their design compromised so that they can meet all mission requirements. There has been continued interest in morphing aircraft in recent years. These proposed morphing systems allow for aircraft to undergo large-scale planform shape changes, such that they adopt the optimum shape for the given mission phase. An aircraft that can change wingspan could operate with high aerodynamic efficiency at cruise, due to a large aspect ratio wing. Upon retraction of the wingspan, higher manoeuverability is gained. For a span-changing aircraft, the wing skins must also change geometry with the span change. One proposed type of skin to do this is a corrugated skin, which displays high anisotropy in stiffness, allowing it to take significant aerodynamic pressure loading, whilst being compliant in the spanwise direction to allow for wing morphing. The method of corrugation used produces sharp leading edges, and so different methods for rounding of the leading edge are examined to determine whether lost aerodynamic performance can be recovered. These are analysed first in 2D, and then the simulations are extended to 3D to determine the effects of corrugation wavelength in the spanwise direction, and the effect of corrugation depth. It is found that the leading edge profile can greatly impact performance, that corrugation wavelength has only a minimal effect on aerodynamic efficiency, and finally that corrugation depth can incur a significant performance penalty.

ight performance and dynamic analysis can be performed. This framework prospectively enables development of morphing concepts, in addition to assessment activities from a conceptual design phase. An example small/ medium Unmanned Air Vehicle (UAV) (mass of 25 kg and nominal aspect ratio of 6.67) is used to demonstrate the tool, presenting results for both symmetric and asymmetric span retraction. The span retraction is performed using the outboard 50% of the main wing, with up to 50% allowable span retraction. Results presented are for a loiter mission. The loiter is at 55 (km/r) where the high speed cruise is from 75-110 km/hr. Span retraction is used to optimise the conguration performance for these ight phases. LTrim and dy- namic (both longitudinal and lateral) results are presented for both high speed cruise and loiter for straight and level conditions. Loiter results include lateral coordinated turn with varying strategies, which include using either rudder span retraction, to trim the UAV. Final results show the eect of modelling _ Ixx using a reduced model for roll dynamics. This investigation shows that the maximum error occurs where the roll and inertia dynamics are matched.

The concept of span morphing aircraft is attracting a lot of attention due to the demands to enhance flight performance and control authority. Corrugated laminates provide a good solution for the skin of a span morphing wing due to their extremely anisotropic behaviour. Although corrugated skins have been proposed for camber morphing, they have not been proposed for span morphing. Hence the main focus of this paper is to optimise the geometry of the corrugated skin to minimize the axial stiffness, with constraints of material strength limits and out-of-plane deformations due to the aerodynamics. Two aerodyanic solvers, Tornado Vortex Lattice Method (VLM) and XFOIL, are compared and a Genetic Algorithm (GA) is used as the optimizer. Parametric modeling and calculation by ANSYS APDL was used to generate the finite element model and perform the analysis automatically based on the global and local geometric parameters. The parameter sensitivity is also analyzed and discussed. The optimization results show that XFOIL is more accurate than VLM for this analysis. The maximum displacement constraint causes the optimizer to choose fewer corrugations rather than increase the sheet thickness. This implies that the thickness has a higher impact than the number of corrugations on the axial stiffness. The optimization results show that the corrugation height and angle are maximized as they seem to have less influence on the maximum out-of-plane displacement.

A comprehensive conceptual design study is performed to assess the potential benefits of span morphing technology and to determine its feasibility when incorporated on medium altitude long endurance unmanned air vehicles. A representative medium altitude long endurance unmanned air vehicle based on the BAE Systems Herti unmanned air vehicle was selected. Stability and control benefits are investigated by operating the morphing span asymmetrically to replace conventional ailerons. The Tornado vortex lattice method was incorporated for aerodynamic predictions. The sensitivity of rolling moment generated by span morphing for different flight parameters (instantaneous vehicular weight and angle of attack) is studied. The variation of roll rate (steady and transient response) with span morphing (for constant rolling moment) for different rolling strategies (extension and retraction) is investigated. It turns out that the optimum rolling strategy is to extend one side of the wing by 22% while retract the other by 22%. Operational performance benefits are investigated by operating the morphing span symmetrically to reduce drag, increase endurance and reduce take-off and landing distances. Twenty-two per cent symmetric span morphing reduces the total drag by 13%, enhances the endurance capability by 6.5% and reduces the take-off field length and landing distance by 28% and 10%, respectively.

Morphing wing strategies can be applied to configure aircraft geometry to successfully complete a mission/s. This requires fulfillment of requirements set within a series of flight phases, which generally specify an objective to be completed and constraints to be satisfied whilst optimising some measure of performance or efficiency. The following paper presents results from a software framework to assess the potential benefits of span morphing in performance and efficiency. An investigation of the effect of morphing on flight stability and control is presented. As an example, span variation from a nominal aspect ratio of 6.67 for a Unmanned Air Vehicle (UAV) of 25kg is presented, with results given for a representative mission profile for typical operations. A structural concept that integrates span retraction is assumed.

This paper develops and models the Compliant Spar concept that allows the wing span to be varied to provide roll control and enhance the operational performance for a medium altitude long endurance (MALE) UAV. The wing semi-span is split into morphing partitions and the concept maybe incorporated in each partition; however only the tip partition is considered here. The Compliant Spar is made of compliant joints arrange in series to allow the partition to be flexible under axial (spanwise) loads but at the same time stiff enough to resist bending loads. Each compliant joint consists of two concentric overlapping Aluminium (AL) 2024-T3 tubes joined together using elastomeric material. Under axial (spanwise) loading, the elastomeric material deforms in shear allowing the overlapping distance between the tubes to vary and hence the length (in the spanwise direction) of the joint/spar to vary. High fidelity modelling of the concept is performed. Then, multidisciplinary design optimisation (MDO) studies are performed to minimise the axial stiffness and the structural mass of the concept for various design constraints. The flexible skin and actuation system to be used are also addressed.

This paper presents the Zigzag wingbox concept that allows the wing span to be varied by 44% (22% extension and 22% retraction). The Zigzag wingbox consists of a rigid part and a morphing part. The rigid part is a semi-monocoque construction that houses the fuel tank and transfers the aerodynamic loads from the morphing part to the fuselage. The morphing part consists of various morphing partitions where in each partition there are two spars each consisting of two beams hinged together. Each morphing partition is covered by flexible skin and is bounded by two ribs through which the spars are connected. The ribs transfer the loads between the spars of adjacent morphing partitions and serves as the main structure to which the flexible skins are to be attached. The Zigzag wingbox concept is then incorporated in the rectangular wing of a medium altitude long endurance (MALE) UAV to enhance its operational performance and provide roll control. Equivalent modelling and preliminary sizing of the concept are performed to assess its feasibility and quantify its potential benefits.

The use of variable wing span to enhance flight performance and control authority of high endurance, medium altitude UAV is investigated. Asymmetric span extension is used to replace ailerons and maintain roll control over the entire flight envelope of the vehicle. The span extension required to generate a rolling moment equal to that produced by ailerons is estimated at four flight points. The study is performed using Tornado Vortex Lattice Method (VLM). 36% increase in wing semi-span is required to maintain roll authority. On the other hand, symmetric span morphing is used to reduce induced drag and enhance the endurance capability of the vehicle. 20% symmetric span morphing was found to be the optimum to reduce the overall drag of the wing by 10% at the start of cruise and 2.5% at the end of cruise. The morphing wing structure is to be designed using Zero Poisson’s ratio Accordion honeycomb with elastomeric skins. The geometry of the honeycomb will be optimised using the Genetic Algorithm (GA) optimiser to minimise the structural weight of the wing while meeting various design constraints.

This paper presents a suggested generic process for selecting and subsequently integrating arbitrary morphing devices specifically during aircraft conceptual and predesign stages. The absence of formally documented procedures by academia and industry alike necessitated the formulation of a standardized objective-driven, top-down approach where implementation of novel adaptive utilities could come into consideration. For the suggested hierarchical approach six top-down Morphing Resolution Levels (MRLs) are introduced where the contents are populated by an array of expert catalogues. Qualitative assessment follows the Georgia Institute of Technology Strategic Planning and Prioritization (SP2) process and encompasses five phases: (1) Problem Definition; (2) Effect Translation; (3) Outer Mold Line Morphing; (4) Structural Layout; and, (5) Technology Selection. This process results in a down-selection of the most pragmatically effective morphing schemes to be considered for further design investigation.

This paper presents the optimum design of a PID controller for the Adaptive Torsion Wing (ATW) using the genetic algorithm (GA) optimiser. The ATW is a thin-wall, twospar wingbox whose torsional stiffness can be adjusted by translating the spar webs in the chordwise direction inward and towards each. The reduction in torsional stiffness allows external aerodynamic loads to deform the wing and maintain its shape. The ATW is integrated within the wing of a representative UAV to replace conventional ailerons and provide roll control. The ATW is modelled as a two-dimensional equivalent aerofoil using bending and torsion shape functions to express the equations of motion in terms of the twist angle and plunge displacement at the wingtip. The full equations of motion for the ATW equivalent aerofoil were derived using Lagrangian mechanics. The aerodynamic lift and moment acting on the aerofoil were modelled using Theodorsen’s unsteady aerodynamic theory. The equations of motion are then linearized around an equilibrium position and the GA is employed to design a PID controller for the linearized system to minimise the actuation power require. Finally, the sizing and selection of a suitable actuator is performed.

Advanced studies have been undertaken using Multidisciplinary Design Optimization (MDO) on the retrofitting of an outboard morphing wing system to an existing conventionally designed commercial passenger jet. Initial studies focusing on the single objective of specific air range improvement for a number of flight phases revealed increases of approximately 4-5% over the baseline aircraft with wing fences across each case. This validated the advantage of re-optimizing the geometric schedules for off-design conditions in comparison with fixed winglets, for which negative effects were observed. Due to the high number of design sensitivities of the outboard wing geometry it has now become necessary to conduct refined studies to analyse the effects of the wing system on additional operational performance metrics, such as take-off, initial climb, approach-climb and landing performance parameters, in order to ascertain a truly holistic representation of the benefits of morphing wing technology. In addition, further effort has been expended to couple the effects of each phase within a multiobjective framework. Thus, refined studies have been performed, incorporating a number of multiobjective optimization methods into a high-end, low fidelity aero-structural-control analysis together with a full engine model and integrated operational performance algorithm. Furthermore, updated aeroelastic functionality and improved aero-structural wing sizing allows for investigation of C-wing configurations. Results reveal the potential for significant field length reductions and climb performance enhancements, while maintaining improvements in cruise performance throughout the entire flight envelope and across multiple stage lengths.

This paper presents the conceptual analysis of a novel Active Aeroelastic Structure (AAS) device, which allows tailored twist deformations of wing structures to be achieved. The Adaptive Torsion Wing (ATW) concept is a thin-walled closed section two-spar wing-box whose torsional stiffness can be adjusted by changing the area enclosed between the front and rear spar webs. This is done by translating the spar webs in the chord-wise direction inward and towards each other using internal actuators. As the webs move closer to each other, the torsional stiffness of the structure reduces, while its bending stiffness in the span-wise direction is unaffected. The reduction in torsional stiffness allows external aerodynamic loads to induce twist on the structure and to maintain its deformed shape. These twist deformations can be controlled by changing the relative position of the webs as a function of the flight conditions to obtain an optimal or targeted level of performance. A Quasistatic Aeroelastic Suite has been developed in MATLAB TM to model the ATW concept and to study its behavior with respect to different web shifting strategies. Finally, the variation of structural figures of merit such as torsion constant, tip twist, shear centre position, and minimum actuation energy are evaluated and discussed.

Aircraft wings are a compromise that allows the aircraft to fly at a range of flight conditions, but the performance at each condition is sub-optimal. The ability of a wing surface to change its geometry during flight has interested researchers and designers over the years as this reduces the design compromises required. Morphing is the short form for metamorphose; however, there is neither an exact definition nor an agreement between the researchers about the type or the extent of the geometrical changes necessary to qualify an aircraft for the title ‘shape morphing.’ Geometrical parameters that can be affected by morphing solutions can be categorized into: planform alteration (span, sweep, and chord), out-of-plane transformation (twist, dihedral/gull, and span-wise bending), and airfoil adjustment (camber and thickness). Changing the wing shape or geometry is not new. Historically, morphing solutions always led to penalties in terms of cost, complexity, or weight, although in certain circumstances, these were overcome by system-level benefits. The current trend for highly efficient and ‘green’ aircraft makes such compromises less acceptable, calling for innovative morphing designs able to provide more benefits and fewer drawbacks. Recent developments in ‘smart’ materials may overcome the limitations and enhance the benefits from existing design solutions. The challenge is to design a structure that is capable of withstanding the prescribed loads, but is also able to change its shape: ideally, there should be no distinction between the structure and the actuation system. The blending of morphing and smart structures in an integrated approach requires multi-disciplinary thinking from the early development, which significantly increases the overall complexity, even at the preliminary design stage. Morphing is a promising enabling technology for the future, next-generation aircraft. However, manufacturers and end users are still too skeptical of the benefits to adopt morphing in the near future. Many developed concepts have a technology readiness level that is still very low. The recent explosive growth of satellite services means that UAVs are the technology of choice for many investigations on wing morphing. This article presents a review of the state-of-the-art on morphing aircraft and focuses on structural, shape-changing morphing concepts for both fixed and rotary wings, with particular reference to active systems. Inflatable solutions have been not considered, and skin issues and challenges are not discussed in detail. Although many interesting concepts have been synthesized, few have progressed to wing tunnel testing, and even fewer have flown. Furthermore, any successful wing morphing system must overcome the weight penalty due to the additional actuation systems.

Recent advances in smart structures and multifunctional materials have facilitated many novel aerospace technologies such as morphing aircraft. A morphing aircraft, bio-inspired by natural fliers, has gained a lot of interest as a potential technology to meet the ambitious goals of the Advisory Council for Aeronautics Research in Europe (ACARE) Vision 2020 and the FlightPath 2050 documents. A morphing aircraft continuously adjusts its wing geometry to enhance flight performance, control authority, and multi-mission capability.[...]

Objective: To assess the performance of a test for breast cancer utilizing synchrotron x-ray diffraction analysis of scalp hair from women undergoing diagnostic radiology assessment. Design and Setting: A double-blinded clinical trial of women who attended diagnostic radiology clinics in Australia. Patients: 1796 women referred for diagnostic radiology, with no previous history of cancer. Main Outcome Measures: Sensitivity, specificity and accuracy of the hair test analysis compared to the gold standard of imaging followed by biopsy where indicated. Results: The hair-based assay had an overall accuracy of >77% and a negative predictive value of 99%. For all women, the sensitivity of both mammography and x-ray diffraction alone was 64%, but when used together the sensitivity rose to 86%. The sensitivity of the hair test for women under the age of 70 was 74%. Conclusion: In this large population trial the association between the presence of breast cancer and an altered hair fibre X-ray diffraction pattern previously reported has been confirmed. It appears that mammography and X-ray diffraction of hair detect different populations of breast cancers, and are synergistic when used together.

Shape memory alloys (SMAs) are a unique class of metallic materials with the ability to recover their original shape at certain characteristic temperatures (shape memory effect), even under high applied loads and large inelastic deformations, or to undergo large strains without plastic deformation or failure (super-elasticity). In this review, we describe the main features of SMAs, their constitutive models and their properties. We also review the fatigue behavior of SMAs and some methods adopted to remove or reduce its undesirable effects. SMAs have been used in a wide variety of applications in different fields. In this review, we focus on the use of shape memory alloys in the context of morphing aircraft, with particular emphasis on variable twist and camber, and also on actuation bandwidth and reduction of power consumption. These applications prove particularly challenging because novel configurations are adopted to maximize integration and effectiveness of SMAs, which play the role of an actuator (using the shape memory effect), often combined with structural, load-carrying capabilities. Iterative and multi-disciplinary modeling is therefore necessary due to the fluid–structure interaction combined with the nonlinear behavior of SMAs.