Journal articles: 'Wings - Load Alleviation'

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Krüger, Wolf R., Yasser M. Meddaikar, Johannes K. S. Dillinger, Jurij Sodja, and Roeland De Breuker. "Application of Aeroelastic Tailoring for Load Alleviation on a Flying Demonstrator Wing." Aerospace 9, no. 10 (September 21, 2022): 535. http://dx.doi.org/10.3390/aerospace9100535.

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This article presents the application of aeroelastic tailoring in the design of wings for a flying demonstrator, as well as the validation of the design methodology with flight test results. The investigations were performed in the FLEXOP project (Flutter Free Flight Envelope Expansion for Economical Performance Improvement), funded under the Horizon 2020 framework. This project aimed at the validation of methods and tools for active flutter control, as well as at the demonstration of the potential of passive load alleviation through composite tailoring. The technologies were to be demonstrated by the design, manufacturing and flight testing of an unmanned aerial vehicle of approximately 7 m wingspan. This article addresses the work towards the load alleviation goals. The design of the primary load-carrying wing-box in this task is performed using a joint DLR–TU Delft optimization strategy. Two sets of wings are designed in order to demonstrate the potential benefits of aeroelastic tailoring—first, a reference wing in which the laminates of the wing-box members are restricted to balanced and symmetric laminates; second, a tailored wing in which the laminates are allowed to be unbalanced, hence allowing for the shear–extension and bending–torsion couplings essential for aeroelastic tailoring. Both designs are numerically optimized, then manufactured and extensively tested to validate and improve the simulation models corresponding to the wing designs. Flight tests are performed, the results of which form the basis for the validation of the applied aeroelastic tailoring approach presented in the article.

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Castrichini, A., V. Hodigere Siddaramaiah, D. E. Calderon, J. E. Cooper, T. Wilson, and Y. Lemmens. "Preliminary investigation of use of flexible folding wing tips for static and dynamic load alleviation." Aeronautical Journal 121, no. 1235 (November 21, 2016): 73–94. http://dx.doi.org/10.1017/aer.2016.108.

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ABSTRACTA recent consideration in aircraft design is the use of folding wing-tips with the aim of enabling higher aspect ratio aircraft with less induced drag while also meeting airport gate limitations. This study investigates the effect of exploiting folding wing-tips in flight as a device to reduce both static and dynamic loads. A representative civil jet aircraft aeroelastic model was used to explore the effect of introducing a wing-tip device, connected to the wings with an elastic hinge, on the load behaviour. For the dynamic cases, vertical discrete gusts and continuous turbulence were considered. The effects of hinge orientation, stiffness, damping and wing-tip weight on the static and dynamic response were investigated. It was found that significant reductions in both the static and dynamic loads were possible. For the case considered, a 25% increase in span using folding wing-tips resulted in almost no increase in loads.

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Liu, Haojie, and Xiao Wang. "Aeroservoelastic design of piezo-composite wings for gust load alleviation." Journal of Fluids and Structures 88 (July 2019): 83–99. http://dx.doi.org/10.1016/j.jfluidstructs.2019.04.010.

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Krishnamurthy, Vikram, and Vega Handojo. "Structural design process and subsequent flight mechanical evaluation in preliminary aircraft design: demonstrated on passenger ride comfort assessment." CEAS Aeronautical Journal 12, no. 2 (April 2021): 457–69. http://dx.doi.org/10.1007/s13272-021-00505-x.

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AbstractNew fuel-efficient aircraft designs have high aspect ratio wings. Consequently, those aircraft are more flexible. Additionally, load alleviation functions are implemented to reduce the structural loads, which results in further reductions of the structural stiffness. At the same time, the structural design impacts other disciplines in preliminary aircraft design, especially flight mechanics. For example, it is important to know how at that design stage such flexible aircraft with load alleviation affect passenger ride comfort in turbulent flight. For an efficient design process, it is essential to answer such questions with accurate multi-disciplinary tools and methods as early as possible to minimize development risk and avoid costly and time-consuming redesign loops. Current available tools and methods are not accurate enough for this task. To address this issue, the DLR MONA based design and the TUB flight mechanical assessment tool MITRA are linked to investigate the impact of the structural design on specific flight mechanical assessments such as passenger ride comfort. This is particularly interesting since the implemented load alleviation functions are designed to reduce loads, and not explicitly to improve passenger ride comfort. By conducting this assessment for a particular aircraft configuration, more insight into passenger ride comfort and the key contributors can be gained during preliminary design. This paper describes the combined toolchain and its application on a generic long-range reference aircraft to investigate the effects of load alleviation functions on passenger ride comfort and discusses the results.

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Ajaj, Rafic M., Erick I. Saavedra Flores, Mohammadreza Amoozgar, and Jonathan E. Cooper. "A Parametric Study on the Aeroelasticity of Flared Hinge Folding Wingtips." Aerospace 8, no. 8 (August 10, 2021): 221. http://dx.doi.org/10.3390/aerospace8080221.

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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.

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An, Chao, Chao Yang, Changchuan Xie, and Yang Meng. "Gust Load Alleviation including Geometric Nonlinearities Based on Dynamic Linearization of Structural ROM." International Journal of Aerospace Engineering 2019 (May 12, 2019): 1–20. http://dx.doi.org/10.1155/2019/3207912.

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This paper describes a framework for an active control technique applied to gust load alleviation (GLA) of a flexible wing, including geometric nonlinearities. Nonlinear structure reduced order model (ROM) and nonplanar double-lattice method (DLM) are used for structural and aerodynamic modeling. The structural modeling method presented herein describes stiffness nonlinearities in polynomial formulation. Nonlinear stiffness can be derived by stepwise regression. Inertia terms are constant with linear approximation. Boundary conditions and kernel functions in the nonplanar DLM are determined by structural deformation to reflect a nonlinear effect. However, the governing equation is still linear. A state-space equation is established in a dynamic linearized system around the prescribed static equilibrium state after nonlinear static aeroelastic analysis. Gust response analysis can be conducted subsequently. For GLA analysis, a classic proportional-integral-derivative (PID) controller treats a servo as an actuator and acceleration as the feedback signal. Moreover, a wind tunnel test has been completed and the effectiveness of the control technology is validated. A remote-controlled (RC) model servo is chosen in the wind tunnel test. Numerical simulation results of gust response analysis reach agreement with test results. Furthermore, the control system gives GLA efficacy of vertical acceleration and root bending moment with the reduction rate being over 20%. The method described in this paper is suitable for gust response analysis and control strategy design for large flexible wings.

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Kilimtzidis, Spyridon, and Vassilis Kostopoulos. "Static Aeroelastic Optimization of High-Aspect-Ratio Composite Aircraft Wings via Surrogate Modeling." Aerospace 10, no. 3 (March 6, 2023): 251. http://dx.doi.org/10.3390/aerospace10030251.

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The race towards cleaner and more efficient commercial aviation demands novel designs featuring improved aerodynamic and structural characteristics, the main pillars that drive aircraft efficiency. Among the many proposed and introduced, the increase in the aspect ratio of the wings enables greater fuel efficiency by reducing induced drag. Nevertheless, such structures are characterised by elevated flexibility, aggravating static and dynamic aeroelastic phenomena. Consequently, the preliminary and conceptual design and optimization stages using high-fidelity numerical tools is rendered extremely intricate and prohibitive in terms of computational cost. Low-fidelity tools, contrastingly, enable computational-burden alleviation. In our approach, a computational framework for the low-fidelity steady-state static aeroelastic optimization of a composite high-aspect-ratio commercial aircraft wing via surrogate modelling is proposed. The methodology starts with the development of the 3D panel method as well of the elements of the surrogate model. The design variables, objective function and constraints which formulate the optimization problem are then provided. Moreover, comparison against rigid aerodynamics indicate the significant load-alleviation capabilities of the present case study. The effect of structural nonlinearities is also explored. The optimization framework is executed and optimal laminates for the structural members are obtained. The optimal structure was deemed critical in panel buckling.

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Breitenstein, C., and R. Radespiel. "Flow simulation of the flight manoeuvres of a large transport aircraft with load alleviation." Aeronautical Journal 126, no. 1298 (October 28, 2021): 681–709. http://dx.doi.org/10.1017/aer.2021.93.

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AbstractA new method for predicting manoeuvre loads on a large transport aircraft with a swept-back wing and a load alleviation system based on control surface deflections is developed. For this purpose, three-dimensional Reynolds-averaged Navier–Stokes (RANS) simulations of the rigid wing–fuselage configuration are performed while the aerodynamics of the tailplane are estimated by means of handbook methods. For a closer analysis, different quasi-steady pitching manoeuvres are chosen based on the CS-25 regulations. One of these manoeuvres is also simulated with active load alleviation, leading to a reduction in the wing-root bending moment by more than 40%. Besides demonstrating the potential of the considered load alleviation system, it is shown which manoeuvres are especially critical in this context and which secondary effects come along with load alleviation.

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Ye, Bo, Youxu Yang, and Zhiyong Cheng. "Flare folding wing tips for static and gust loads alleviation." Journal of Physics: Conference Series 2459, no. 1 (March 1, 2023): 012071. http://dx.doi.org/10.1088/1742-6596/2459/1/012071.

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Abstract The Passive gust load alleviation device can effectively simplify the control system by relying on the adaptive deformation of the structure. This research examines the influence of using folding wingtips during flight as a means of reducing static loads and gusty loads. Effects of hinge direction, wing-tip weight, stiffness and wing-tip centre of gravity on static and gust alleviation performance has been examined. The results show that the flare folding wing-tip can significantly reduce the static load and gust load of the aircraft. In a static aeroelastic trim analysis, a folding wingtip can increase span by 25% without increasing the wing root bending moment and decrease the trim angle of attack by 0.14°. In the gust response analysis, the maximum bending moment of wing root can be decrease by nearly 50% compared with the fixed wing-tip, only 17% higher than the baseline model without a wing-tip.

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Gatto, A., P. Bourdin, and M. I. Friswell. "Experimental Investigation into the Control and Load Alleviation Capabilities of Articulated Winglets." International Journal of Aerospace Engineering 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/789501.

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An experimental investigation into the real-time flow and control characteristics of a flying wing with articulated winglets is described in this paper. The philosophy of the concept centres around the use of active, in-flight adjustment of each wing's winglet dihedral angle, both as a primary means of aircraft roll control (single winglet actuation) and though smaller equal and simultaneous winglet deflections, tailor and alleviate main wing load. Results presented in this paper do provide good evidence of the concept's ability to adequately perform both tasks, although for the current chosen wing/winglet configuration, roll control authority was unable to achieve, per unit of control surface deflection, the same level of performance set by modern aileron-based roll control methodologies.

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Handojo, Vega, Jan Himisch, Kjell Bramsiepe, Wolf Reiner Krüger, and Lorenz Tichy. "Potential Estimation of Load Alleviation and Future Technologies in Reducing Aircraft Structural Mass." Aerospace 9, no. 8 (July 29, 2022): 412. http://dx.doi.org/10.3390/aerospace9080412.

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In recent years, load alleviation technologies have been more widely used in transport aircraft. For aircraft already in service, load alleviation can contribute in extending the fatigue life, or enable small configurational changes. If load alleviation is considered in the aircraft design process, the structural mass of the aircraft can be reduced. This paper investigates various maneuver and gust load alleviation algorithms as well as potential future technologies regarding flight operation, turbulence forecast and material science, and it evaluates the mass reduction that can be achieved. In doing so, a long-range transport aircraft was taken as the reference, and the considered load case conditions were 1-cos gusts, maneuvers and quasi-steady landing. Based upon the loads, the composite structure of the lifting surfaces was optimized, while the secondary masses as well as the wing planform were kept unchanged. With all technologies implemented, a reduction of the wing box mass by 26.5% or 4.4% of the operating empty mass could be achieved.

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Saetti, Umberto, and Joseph F. Horn. "Load Alleviation Flight Control Design using High-Order Dynamic Models." Journal of the American Helicopter Society 65, no. 3 (July 1, 2020): 1–15. http://dx.doi.org/10.4050/jahs.65.032009.

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The present study considers two notional rotorcraft models: a conventional utility helicopter, representative of an H-60, and a wing-only compound utility rotorcraft, representative of an H-60 with a wing similar to the X-49A wing. An explicit model following (EMF) control scheme is designed to achieve stability and desired rate command / attitude hold response around the roll, pitch, and yaw axes, while alleviating vibratory loads through both feed-forward and feedback compensation. The harmonic decomposition methodology is extended to enable optimization of primary flight control laws that mitigate vibratory loads. Specifically, linear time-periodic systems representative of the periodic rotorcraft dynamics are approximated by linear time-invariant (LTI) models. The LTI models are subsequently reduced and used in linear quadratic regulator (LQR) design to constrain the harmonics of the vibratory loads. Both fuselage state feedback and rotor state feedback are considered. A pseudo-inverse strategy is incorporated into the EMF scheme for redundant control allocation on the compound configuration. Simulations of the load alleviating controllers are compared to results from a baseline controller. Finally, an analysis is performed to assess the impact that load alleviating control action, rotor state feedback, and pseudo-inverse have on handling qualities in terms of ADS-33E specifications.

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Ibren, Mohamed, Erwin Sulaeman, Amelda D. Andan, Yulfian Aminanda, and A. K. A. Halim. "Gust Load Alleviation of Flexible Composite Wing." CFD Letters 12, no. 4 (April 20, 2020): 79–89. http://dx.doi.org/10.37934/cfdl.12.4.7989.

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Bordogna, Marco Tito, Paul Lancelot, Dimitri Bettebghor, and Roeland De Breuker. "Static and dynamic aeroelastic tailoring with composite blending and manoeuvre load alleviation." Structural and Multidisciplinary Optimization 61, no. 5 (January 9, 2020): 2193–216. http://dx.doi.org/10.1007/s00158-019-02446-w.

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AbstractIn aircraft design, proper tailoring of composite anisotropic characteristics allows to achieve weight saving while maintaining good aeroelastic performance. To further improve the design, dynamic loads and manufacturing constraints should be integrated in the design process. The objective of this paper is to evaluate how the introduction of continuous blending constraints affects the optimum design and the retrieval of the final stacking sequence for a regional aircraft wing. The effect of the blending constraints on the optimum design (1) focuses on static and dynamic loading conditions and identifies the ones driving the optimization and (2) explores the potential weight saving due to the implementation of a manoeuvre load alleviation (MLA) strategy. Results show that while dynamic gust loads can be critical for wing design, in the case of a regional aircraft, their influence is minimal. Nevertheless, MLA strategies can reduce the impact of static loads on the final design in favour of gust loads, underlining the importance of considering such load-cases in the optimisation. In both cases, blending does not strongly affect the load criticality and retrieve a slightly heavier design. Finally, blending constraints confirmed their significant influence on the final discrete design and their capability to produce more manufacturable structures.

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Paletta, Nicola, Marika Belardo, and Modesto Pecora. "Load Alleviation on a Joined-Wing Unmanned Aircraft." Journal of Aircraft 47, no. 6 (November 2010): 2005–16. http://dx.doi.org/10.2514/1.c000265.

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Khalil, Khalid, Salvatore Asaro, and André Bauknecht. "Active Flow Control Devices for Wing Load Alleviation." Journal of Aircraft 59, no. 2 (March 2022): 458–73. http://dx.doi.org/10.2514/1.c036426.

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Schildkamp, Roderick, Jing Chang, Jurij Sodja, Roeland De Breuker, and Xuerui Wang. "Incremental Nonlinear Control for Aeroelastic Wing Load Alleviation and Flutter Suppression." Actuators 12, no. 7 (July 9, 2023): 280. http://dx.doi.org/10.3390/act12070280.

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This paper proposes an incremental nonlinear control method for an aeroelastic system’s gust load alleviation and active flutter suppression. These two control objectives can be achieved without modifying the control architecture or the control parameters. The proposed method has guaranteed stability in the Lyapunov sense and also has robustness against external disturbances and model mismatches. The effectiveness of this control method is validated by wind tunnel tests of an active aeroelastic parametric wing apparatus, which is a typical wing section containing heave, pitch, flap, and spoiler degrees of freedom. Wind tunnel experiment results show that the proposed nonlinear incremental control can reduce the maximum gust loads by up to 46.7% and the root mean square of gust loads by up to 72.9%, while expanding the flutter margin by up to 15.9%.

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Versiani, Thiago de Souza Siqueira, Flávio J. Silvestre, Antônio B. Guimarães Neto, Domingos A. Rade, Roberto Gil Annes da Silva, Maurício V. Donadon, Rafael M. Bertolin, and Gefferson C. Silva. "Gust load alleviation in a flexible smart idealized wing." Aerospace Science and Technology 86 (March 2019): 762–74. http://dx.doi.org/10.1016/j.ast.2019.01.058.

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Ossmann, Daniel, and Manuel Pusch. "Fault Tolerant Control of an Experimental Flexible Wing." Aerospace 6, no. 7 (June 30, 2019): 76. http://dx.doi.org/10.3390/aerospace6070076.

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Active control techniques are a key factor in today’s aircraft developments to reduce structural loads and thereby enable highly efficient aircraft designs. Likewise, increasing the autonomy of aircraft systems aims to maintain the highest degree of operational performance also in fault scenarios. Motivated by these two aspects, this article describes the design and validation of a fault tolerant gust load alleviation control system on a flexible wing in a wind tunnel. The baseline gust load alleviation controller isolates and damps the weakly damped first wing bending mode. The mode isolation is performed via an H 2 -optimal blending of control inputs and measurement outputs, which allows for the design of a simple single-input single-output controller to actively damp the mode. To handle actuator faults, a control allocation scheme based on quadratic programming is implemented, which distributes the required control energy to the remaining available control surfaces. The control allocation is triggered in fault scenarios by a fault detection scheme developed to monitor the actuators using nullspace based filter design techniques. Finally, the fault tolerant control scheme is verified by wind tunnel experiments.

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Lobo do Vale, José, John Raffaelli, and Afzal Suleman. "Experimental Validation and Evaluation of a Coupled Twist-Camber Morphing Wing Concept." Applied Sciences 11, no. 22 (November 11, 2021): 10631. http://dx.doi.org/10.3390/app112210631.

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A morphing wing concept allowing for coupled twist-camber shape adaptation is proposed. The design is based on an optimized thickness distribution both spanwise and chordwise to be able to morph the wing sections into targeted airfoil shapes. Simultaneously, the spanwise twist is affected by the actuation. The concept provides a higher degree of control on the lift distribution which can be used for roll control, drag minimization, and active load alleviation. Static deformation and flight tests have been performed to evaluate and quantify the performance of the proposed mechanism. The ground tests include mapped actuated wing shapes, and wing mass and actuation power requirements. Roll authority, load alleviation, and aerodynamic efficiency estimates for different configurations were calculated using a lifting line theory coupled with viscous 2D airfoil data. Roll authority was estimated to be low when compared to a general aviation aircraft while the load alleviation capability was found to be high. Differences between the lift to drag ratio between the reference and morphing wing configurations are considerable. Mass and actuation energy present challenges that can be mitigated. The flight tests were used to qualitatively assess the roll control capability of the prototype, which was found to be adequate.

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Wang, Xuerui, Tigran Mkhoyan, Iren Mkhoyan, and Roeland De Breuker. "Seamless Active Morphing Wing Simultaneous Gust and Maneuver Load Alleviation." Journal of Guidance, Control, and Dynamics 44, no. 9 (September 2021): 1649–62. http://dx.doi.org/10.2514/1.g005870.

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Liu, Xiang, and Qin Sun. "Gust Load Alleviation with Robust Control for a Flexible Wing." Shock and Vibration 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/1060574.

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Traditional methods for gust alleviation of aircraft are mostly proposed based on a specific flight condition. In this paper, robust control laws are designed for a large flexible wing with uncertainty in Mach number and dynamic pressure. To accurately describe the aeroelastic model over a large flight envelope, a nonlinear parameter-varying model is developed which is a function of both Mach number and dynamic pressure. Then a linear fractional transformation is established accordingly and a modified model order reduction technique is applied to reduce the size of the uncertainty block. The developed model, in which the statistic nature of the gust is considered by using the Dryden power spectral density function, enables the use ofμ-synthesis procedures for controller design. The simulations show that theμcontroller can always effectively reduce the wing root shear force and bending moment at a given range of Mach number and dynamic pressure.

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Castrichini, A., V. Hodigere Siddaramaiah, D. E. Calderon, J. E. Cooper, T. Wilson, and Y. Lemmens. "Nonlinear Folding Wing Tips for Gust Loads Alleviation." Journal of Aircraft 53, no. 5 (September 2016): 1391–99. http://dx.doi.org/10.2514/1.c033474.

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Tang, Martin, Marc Böswald, Yves Govers, and Manuel Pusch. "Identification and assessment of a nonlinear dynamic actuator model for controlling an experimental flexible wing." CEAS Aeronautical Journal 12, no. 2 (April 2021): 413–26. http://dx.doi.org/10.1007/s13272-021-00504-y.

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AbstractIn this paper, the effect of nonlinear actuator dynamics on the performance of an active load alleviation system for an experimental flexible wing is studied. Common nonlinearities such as backlash or rate limits are considered for the control surface actuator. An aeroelastic simulation model of a flexible wing with control surface is being used. With this, a parameter study is carried out to quantify the impact of the individual nonlinearities on the overall closed-loop performance by means of describing functions. Finally, the nonlinear actuator model with parameters identified from dedicated tests is experimentally validated allowing for an accurate prediction of the expected gust load alleviation performance.

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Dimino, Ignazio, Giovanni Andreutti, Frédéric Moens, Federico Fonte, Rosario Pecora, and Antonio Concilio. "Integrated Design of a Morphing Winglet for Active Load Control and Alleviation of Turboprop Regional Aircraft." Applied Sciences 11, no. 5 (March 9, 2021): 2439. http://dx.doi.org/10.3390/app11052439.

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Aircraft winglets are well-established devices that improve aircraft fuel efficiency by enabling a higher lift over drag ratios and lower induced drag. Retrofitting winglets to existing aircraft also increases aircraft payload/range by the same order of the fuel burn savings, although the additional loads and moments imparted to the wing may impact structural interfaces, adding more weight to the wing. Winglet installation on aircraft wing influences numerous design parameters and requires a proper balance between aerodynamics and weight efficiency. Advanced dynamic aeroelastic analyses of the wing/winglet structure are also crucial for this assessment. Within the scope of the Clean Sky 2 REG IADP Airgreen 2 project, targeting novel technologies for next-generation regional aircraft, this paper deals with the integrated design of a full-scale morphing winglet for the purpose of improving aircraft aerodynamic efficiency in off-design flight conditions, lowering wing-bending moments due to maneuvers and increasing aircraft flight stability through morphing technology. A fault-tolerant morphing winglet architecture, based on two independent and asynchronous control surfaces with variable camber and differential settings, is presented. The system is designed to face different flight situations by a proper action on the movable control tabs. The potential for reducing wing and winglet loads by means of the winglet control surfaces is numerically assessed, along with the expected aerodynamic performance and the actuation systems’ integration in the winglet surface geometry. Such a device was designed by CIRA for regional aircraft installation, whereas the aerodynamic benefits and performance were estimated by ONERA on the natural laminar flow wing. An active load controller was developed by PoliMI and UniNA performed aeroelastic trade-offs and flutter calculations due to the coupling of winglet movable harmonics and aircraft wing bending and torsion.

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Wada, Daichi, Masato Tamayama, and Hideaki Murayama. "Smart wing load alleviation through optical fiber sensing, load identification, and deep reinforcement learning." Engineering Research Express 2, no. 4 (October 7, 2020): 045004. http://dx.doi.org/10.1088/2631-8695/abbb59.

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Sinha, Kautuk, Thomas Klimmek, Matthias Schulze, and Vega Handojo. "Loads analysis and structural optimization of a high aspect ratio, composite wing aircraft." CEAS Aeronautical Journal 12, no. 2 (February 7, 2021): 233–43. http://dx.doi.org/10.1007/s13272-021-00494-x.

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AbstractComposite structures have shown a prominent impact in the aircraft structural design. With an increasing shift towards incorporating more composite materials in the primary aircraft structure it is imperative to have corresponding design tools to simplify the design process. In the present work, a simplified implementation for composite optimization has been developed within the DLR-AE (German Aerospace Centre, Institute of Aeroelasticity) automated aeroelastic structural design framework cpacs-MONA. This paper presents the results of structural optimization of a high aspect ratio composite wing aircraft model developed in the DLR project ATLAs. The generation of almost all involved simulation models for this study is done using the in-house DLR tool ModGen. An aeroelastic trim analysis is conducted for various manoeuvre and gust conditions. A load selection process is used to determine the most relevant sizing load cases. A comparison is made between the optimization results of a composite wing and an aluminium wing to demonstrate the more favourable strength to weight ratio of the composite wing. A manoeuvre load alleviation procedure has been introduced in the load calculation process. The results show further weight savings in the design process when load alleviation is utilized due to reduction in the span wise bending moment.

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Darden, Christine M. "The influence of leading-edge load alleviation on supersonic wing design." Journal of Aircraft 22, no. 1 (January 1985): 71–77. http://dx.doi.org/10.2514/3.45082.

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Matsuzaki, Y., T. Ueda, Y. Miyazawa, and H. Matsushita. "Gust load alleviation of a transport-type wing - Test and analysis." Journal of Aircraft 26, no. 4 (April 1989): 322–27. http://dx.doi.org/10.2514/3.45763.

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Suresh, P. S., G. Radhakrishnan, and K. Shankar. "Manoeuvre load alleviation using multi-objective optimisation for combat aircraft wing." International Journal of Design Engineering 3, no. 2 (2010): 195. http://dx.doi.org/10.1504/ijde.2010.034864.

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Sodja, Jurij, Noud P. M. Werter, and Roeland De Breuker. "Aeroelastic Demonstrator Wing Design for Maneuver Load Alleviation Under Cruise Shape Constraint." Journal of Aircraft 58, no. 3 (May 2021): 448–66. http://dx.doi.org/10.2514/1.c035955.

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Li, Yonghong, and Ning Qin. "Gust load alleviation on an aircraft wing by trailing edge Circulation Control." Journal of Fluids and Structures 107 (November 2021): 103407. http://dx.doi.org/10.1016/j.jfluidstructs.2021.103407.

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Bernhammer, Lars O., Sjors PW Teeuwen, Roeland De Breuker, Gijs J. van der Veen, and Edwin van Solingen. "Gust load alleviation of an unmanned aerial vehicle wing using variable camber." Journal of Intelligent Material Systems and Structures 25, no. 7 (November 7, 2013): 795–805. http://dx.doi.org/10.1177/1045389x13511010.

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Gennaretti, M., and C. Ponzi. "Finite-state aerodynamic modelling for gust load alleviation of wing–tail configurations." Aeronautical Journal 103, no. 1021 (March 1999): 147–58. http://dx.doi.org/10.1017/s0001924000064964.

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Abstract A finite-state aerodynamics methodology is proposed for the analysis of the forces generated by a gust. To illustrate and assess the methodology, gust-response and gust-alleviation applications are included. Finite-state aerodynamics denotes a technique to approximate aerodynamic loads so as to yield an aircraft model of the type ẋ = Ax + Bu (state-space formulation). In this paper, a finite-state formulation is proposed to include the presence of a gust. The aerodynamic loads to be approximated are evaluated here by using a frequency-domain boundary-element formulation; the flow is assumed to be irrotational except for a zero-thickness vortex layer (wake). The gust-alleviation application consists of determining a control law for reducing the response to a vertical gust disturbance, as measured by the centre of mass acceleration. Two optimal-control approaches are considered for the synthesis of the control law: one uses the classical linear-quadratic regulator (LQR), whereas the second includes the additional feed-forward of the gust velocity ahead of the aircraft. Deflections of ailerons and elevators are assumed to be the control variables. Numerical results deal with responses to both a deterministic ‘1 – cosine’ gust distribution and a stochastic von Kármán spectrum. They indicate that the finite-state aerodynamic model proposed is capable of approximating, with a high level of accuracy, both the aerodynamic loads induced by the aircraft kinematics variables and those induced by the control variables, over a wide frequency range.

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35

Skinner, S. N., and H. Zare-Behtash. "Study of a C-wing configuration for passive drag and load alleviation." Journal of Fluids and Structures 78 (April 2018): 175–96. http://dx.doi.org/10.1016/j.jfluidstructs.2017.12.018.

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Li, Hongkun, Rui Huang, Yonghui Zhao, and Haiyan Hu. "Maneuver load alleviation for high performance aircraft robust to flight condition variations." Journal of Vibration and Control 25, no. 5 (November 18, 2018): 1044–57. http://dx.doi.org/10.1177/1077546318810033.

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The design of a robust maneuver load alleviation (MLA) system for a high-performance aircraft is studied in this paper. First, the aeroservoelastic (ASE) models of a high-performance military aircraft in climbing maneuver at varying Mach numbers are established. Then, a linear parameter-varying (LPV) model of the ASE systems is constructed and an [Formula: see text] robust controller is designed based on the LPV model. The robust control is realized via a pair of outboard ailerons to alleviate the wing-root bending moments in the climbing maneuvers. To compensate the loss of performance in the load alleviation, a controller based on recurrent neural networks is designed in the flight control. Finally, some numerical simulations are made to testify the performance and robustness of the MLA system.

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37

SUZUKI, Shinji, and Satoshi YONEZAWA. "Optimum Structural Design of Cantilevered Rectangular Elastic Wing with Gust Load Alleviation System." Journal of the Japan Society for Aeronautical and Space Sciences 39, no. 451 (1991): 419–25. http://dx.doi.org/10.2322/jjsass1969.39.419.

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38

Fujimori, A., H. Ohta, and P. N. Nikiforuk. "Controller Designs of a Gust Load Alleviation System for an Elastic Rectangular Wing." IFAC Proceedings Volumes 22, no. 7 (July 1989): 153–58. http://dx.doi.org/10.1016/s1474-6670(17)53399-6.

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39

Cheung, R. C. M., D. Rezgui, J. E. Cooper, and T. Wilson. "Testing of Folding Wingtip for Gust Load Alleviation of Flexible High-Aspect-Ratio Wing." Journal of Aircraft 57, no. 5 (September 2020): 876–88. http://dx.doi.org/10.2514/1.c035732.

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40

Meyer, Patrick, Sebastian Lück, Tobias Spuhler, Christoph Bode, Christian Hühne, Jens Friedrichs, and Michael Sinapius. "Transient Dynamic System Behavior of Pressure Actuated Cellular Structures in a Morphing Wing." Aerospace 8, no. 3 (March 20, 2021): 89. http://dx.doi.org/10.3390/aerospace8030089.

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High aspect ratio aircraft have a significantly reduced induced drag, but have only limited installation space for control surfaces near the wingtip. This paper describes a multidisciplinary design methodology for a morphing aileron that is based on pressure-actuated cellular structures (PACS). The focus of this work is on the transient dynamic system behavior of the multi-functional aileron. Decisive design aspects are the actuation speed, the resistance against external loads, and constraints preparing for a future wind tunnel test. The structural stiffness under varying aerodynamic loads is examined while using a reduced-order truss model and a high-fidelity finite element analysis. The simulations of the internal flow investigate the transient pressurization process that limits the dynamic actuator response. The authors present a reduced-order model based on the Pseudo Bond Graph methodology enabling time-efficient flow simulation and compare the results to computational fluid dynamic simulations. The findings of this work demonstrate high structural resistance against external forces and the feasibility of high actuation speeds over the entire operating envelope. Future research will incorporate the fluid–structure interaction and the assessment of load alleviation capability.

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Schirrer, A., C. Westermayer, M. Hemedi, and M. Kozek. "Actuator and Sensor Positioning Optimization in Control Design for a Large BWB Passenger Aircraft." ISRN Mechanical Engineering 2011 (June 26, 2011): 1–11. http://dx.doi.org/10.5402/2011/635815.

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This paper states an approach to actuator and sensor positioning optimization and design in the control system design of a large blended wing body (BWB) passenger aircraft. Numerous objectives have to be achieved by the control system: loads alleviation, vibration attenuation, and the fulfillment of handling quality requirements. Exploiting the system structure and existing system knowledge (excitation, comfort, and load formulations), evaluation criteria are designed to assess actuator and sensor effectiveness and efficiency for the aircraft dynamic range of interest. The tasks of optimal actuator and sensor positioning, actuator sizing, and actuator bandwidth requirements are investigated, whereby solutions that are robust are sought with respect to parameter variations. The results are shown on a BWB passenger aircraft model and verified using a normalized closed-loop performance assessment approach.

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42

Hao, Shuai, Tielin Ma, Yi Wang, Huadong Li, Shiwei Zhao, and Puxue Tan. "ArticleGust Alleviation by Active–Passive Combined Control of the Flight Platform and Antenna Array for a Flying Wing SensorCraft." Aerospace 10, no. 6 (May 29, 2023): 511. http://dx.doi.org/10.3390/aerospace10060511.

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SensorCraft is an intelligence, surveillance, and reconnaissance (ISR) system that integrates unmanned flight platforms and airborne antenna arrays. Under gust loads, the high–aspect–ratio, light–wing structure of SensorCraft has considerable bending and torsion deformation, affecting the flight performance of unmanned flight platforms and leading to the loss of antenna arrays’ electromagnetic performance. Taking SensorCraft as the background, a wing conformal antenna array was designed, an aircraft model with a passive wingtip device was established, a control law was developed by the LQG/LTR method, and a gust alleviation active–passive combined control method of a “LQG/LTR active controller + passive wingtip device” was proposed. By constructing an unsteady aerodynamic reduced–order model (ROM) based on the Volterra series and a conformal array pattern fast method based on the modal form, the effectiveness of the gust alleviation active–passive combined control method on the aircraft platform and antenna array was analyzed. The results show that structural deformation of the wing conformal antenna leads to changes in the main lobe gain, beam direction, and sidelobe level. The active–passive gust alleviation method has obvious advantages. Compared with the LQG/LTR active gust alleviation method, the peak value of wingtip displacement is reduced by 15.6%, and the peak value of the gain loss is reduced by 0.72 dB, which is conducive to better performance of the airborne conformal antenna array.

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Sheta, Essam F. "A Multidisciplinary Analysis of Tail Buffeting Alleviation Using Streamwise Fences." Journal of Vibration and Control 9, no. 5 (May 2003): 583–604. http://dx.doi.org/10.1177/1077546303009005005.

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A multidisciplinary analysis of vertical tail buffeting and buffeting alleviation of generic fighter aircraft is conducted. This complex multidisciplinary problem is solved for the fluid dynamics, structure dynamics, fluid-structure coupling, and grid deformation using a computing environment that controls the temporal synchronization of the data transfer between the analysis modules. The generic fighter aircraft consists of a sharp-edged delta wing with an aspect ratio of one and a swept-back, flexible, vertical twin tail with a taper ratio of 0.23. Twin streamwise fences are located at the 30% chord-station of the delta wing. The fences are used to alter the vortical flow and to delay the onset of vortex breakdown above the delta wing, in order to alleviate the twin-tail buffeting. The effect of the geometrical shape of the fences on the buffeting responses is investigated. The performance of the fences over a wide range of high angles of attack is also investigated. The trapezoidal configuration of the fences at a taper ratio of 0.7 produced the most favorable results. The results indicated that the fences are effective in reducing the aeroelastic loads and responses, especially at angles of attack less than 30°.

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Suzuki, Shinji, and Satoshi Yonezawa. "Simultaneous structure/control design optimization of a wing structure with a gust load alleviation system." Journal of Aircraft 30, no. 2 (March 1993): 268–74. http://dx.doi.org/10.2514/3.48276.

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Balatti, Davide, Hamed Haddad Khodaparast, Michael I. Friswell, Marinos Manolesos, and Andrea Castrichini. "Experimental and numerical investigation of an aircraft wing with hinged wingtip for gust load alleviation." Journal of Fluids and Structures 119 (May 2023): 103892. http://dx.doi.org/10.1016/j.jfluidstructs.2023.103892.

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Dillinger, Johannes K. S., Yasser M. Meddaikar, Jannis Lübker, Manuel Pusch, and Thiemo Kier. "Design and Optimization of an Aeroservoelastic Wind Tunnel Model." Fluids 5, no. 1 (March 17, 2020): 35. http://dx.doi.org/10.3390/fluids5010035.

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Through the combination of passive and active load alleviation techniques, this paper presents the design, optimization, manufacturing, and update of a flexible composite wind tunnel model. In a first step, starting from the specification of an adequate wing and trailing edge flap geometry, passive, static aeroelastic stiffness optimizations for various objective functions have been performed. The second optimization step comprised a discretization of the continuous stiffness distributions, resulting in manufacturable stacking sequences. In order to determine which of the objective functions investigated in the passive structural optimization most efficiently complemented the projected active control schemes, the condensed modal finite element models were integrated in an aeroelastic model, involving a dedicated gust load alleviation controller. The most promising design was selected for manufacturing. The finite element representation could be updated to conform to the measured eigenfrequencies, based on the dynamic identification of the model. Eventually, a wind tunnel test campaign was conducted in November 2018 and results have been examined in separate reports.

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Zhou, Yitao, Zhigang Wu, and Chao Yang. "Gust Alleviation and Wind Tunnel Test by Using Combined Feedforward Control and Feedback Control." Aerospace 9, no. 4 (April 18, 2022): 225. http://dx.doi.org/10.3390/aerospace9040225.

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Gust alleviation is of great significance for improving aircraft ride quality and reducing gust load. Using aircraft response (feedback control) and gust disturbance information (feedforward control) to improve the gust alleviation effect is worthy of attention. In this paper, a combined control system (CCS) composed of feedforward control system (FFCS) and feedback control system (FBCS) is designed and analyzed. At the same time, the gust alleviation effect of the CCS, the single FFCS and the single FBCS are analyzed and compared by means of numerical simulation and wind tunnel test, respectively. Taking a flexible wing as the research object, the gust alleviation effects of three control systems under different forms of gust excitation (1-cos discrete gust, sine gust and Dryden turbulence) are analyzed by numerical simulation. In the wind tunnel test, the sine gust generated by a gust generator was used, and the gust alleviation test was carried out under different wind speeds and gust frequencies. The simulation and experimental results show that the CCS has better gust alleviation performance for various gust excitations. When comparing FFCS and FBCS, the FFCS has better robustness and control effect than the FBCS. When comparing FFCS and CCS, the better the alleviation effect of FFCS, the more difficult it is to achieve significant effect improvement by using CCS, which is obtained by adding FBCS on the FFCS.

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Bi, Ying, Changchuan Xie, Chao An, and Chao Yang. "Gust load alleviation wind tunnel tests of a large-aspect-ratio flexible wing with piezoelectric control." Chinese Journal of Aeronautics 30, no. 1 (February 2017): 292–309. http://dx.doi.org/10.1016/j.cja.2016.12.028.

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Szczyglowski, Christopher P., Simon A. Neild, Branislav Titurus, Jason Z. Jiang, and Etienne Coetzee. "Passive Gust Loads Alleviation in a Truss-Braced Wing Using an Inerter-Based Device." Journal of Aircraft 56, no. 6 (November 2019): 2260–71. http://dx.doi.org/10.2514/1.c035452.

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FUJIMORI, Atsushi, and Hirobumi OHTA. "Designs of a gust load alleviation system for a cantilevered elastic rectangular wing and wind-tunnel tests." Journal of the Japan Society for Aeronautical and Space Sciences 38, no. 441 (1990): 524–32. http://dx.doi.org/10.2322/jjsass1969.38.524.

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Journal articles on the topic 'Wings - Load Alleviation'

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