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De Breuker R. - One of the best experts on this subject based on the ideXlab platform.

  • The interaction between active aeroelastic control and structural tailoring in aeroservoelastic wing design
    'Elsevier BV', 2021
    Co-Authors: Binder S., Wildschek Andreas, De Breuker R.
    Abstract:

    This paper presents an analysis of the interaction and trade-off between active aeroelastic control and passive structural tailoring on a free-flying fully flexible aircraft model. Both technologies are included in the preliminary design of a typical transport aircraft configuration with a conventional control surface layout containing trailing edge control surfaces and spoilers. The passive structural tailoring is facilitated by exploiting the anisotropic properties of composite materials to steer the static and dynamic aeroelastic behaviour. Active aeroelastic control is implemented by scheduled control surface deflections redistributing the aerodynamic Loads during manoeuvres to achieve manoeuvre Load alleviation and a feed-forward control law for Gust Load alleviation. The panel-based aerodynamic modelling of spoiler deflections is improved by a correction of the spatial distribution of the boundary condition derived from higher fidelity simulation data. The optimisation of active control laws requires the consideration of constraints of the actuation system, namely rate and deflection saturation, in a nonlinear manner. The interaction of manoeuvre Load alleviation, Gust Load alleviation and passive structural tailoring is investigated on the basis of results of different aeroservoelastic optimisations. Therefore the primary wing structure is simultaneously optimised with the individual technologies being activated or deactivated, resulting in eight different wing structures. The results of the individual and combined optimisations reveal significant design differences. The potentials of the different technologies can only be optimally exploited by simultaneous optimisation. The paper concludes with a study of the sensitivity of the major findings with respect to the knockdown factor for failure applied to the material properties. A substantial shift of effectiveness from active aeroelastic control to passive structural tailoring is observed with increased allowables resulting in more flexible and hence less stiff wing designs.Aerospace Structures & Computational Mechanic

  • Results of an Aeroelastically Tailored Wing on the FLEXOP Demonstrator Aircraft
    'American Institute of Aeronautics and Astronautics (AIAA)', 2020
    Co-Authors: Roessler Christian, De Breuker R., Ossmann Daniel, Teubl Daniel, Meddaikar Yasser, Wüstenhagen Matthias, Sodja J., Luspay Tamás, Gyulai László
    Abstract:

    The idea of the EU funded FLEXOP project is to raise efficiency of a currently existing wing by derivative solution with higher aspect ratio at no excess structural weight. In order to enable such a resulting highly flexible wing the project goal is to develop methods for active suppression of flutter and passive Load alleviation. The developed methods will be tested and validated with a UAV flutter demonstrator. The demonstrator is a 7m wingspan, 65kg MTOW UAV equipped with a jet engine. It features three different wing pairs. The first wing is a stiff design reference case, which is flown to get the baseline measurements for comparison. The second one is a wing designed very flexible specifically for active flutter control. The third wing is aeroelastically tailored for Gust Load alleviation. The paper describes the results of the aeroelastically tailored wing compared to the baseline reference wing.Aerospace Structures & Computational Mechanic

  • Flexible Aircraft Gust Load Alleviation with Incremental Nonlinear Dynamic Inversion
    'American Institute of Aeronautics and Astronautics (AIAA)', 2018
    Co-Authors: Wang X., Chu Q. P., Van Kampen E., De Breuker R.
    Abstract:

    In this paper, an Incremental Nonlinear Dynamic Inversion (INDI) controller isdeveloped for the flexible aircraft Gust Load alleviation (GLA) problem. First, a flexible aircraft model captures both inertia and aerodynamic coupling effects between flight dynamics and structural vibration dynamics is presented. Then an INDI GLA controller is designed for this aircraft model based on sensor measurements and the Kalman filter online estimation. Besides, the fifth order Padé approximation is used to model the pure time delay in the state estimation. Furthermore, simulations of the flexible aircraft flying through various spatial turbulence and Gust fields demonstrate the effectiveness of the proposed controller on rigid-body motion regulation, vertical Load alleviation, wing root bending moment reduction and elastic modes suppression. Additionally, numerical perturbation tests and a Monte-Carlo study show the robustness of the proposed controller to aerodynamic model uncertainties

  • Passively actuated spoiler for Gust Load alleviation
    2016
    Co-Authors: Lancelot P.m.g.j., De Breuker R.
    Abstract:

    This paper summarises a conceptual study regarding a passively actuated spoiler for Gust Load alleviation. The design of such system is intended to limit the use of computers, sensors and actuators to operate the device. The study mainly relies on using Theodorsen’s unsteady flow theory for a typical airfoil section. To cope with the limitations of this type of model for spoiler aerodynamic, corrections are brought from unsteady high fidelity flow simulations by means of transfer functions. The outcome is a 2D aeroelastic model with three degrees of freedom. It describes the spoiler contribution to the overall aeroelastic behaviour of the airfoil in the event of a Gust encounter. Results show that the spoiler can help to reduce Loads passively, but requires to be retracted with an active system to work properly

  • Passively actuated spoiler for Gust Load alleviation
    2016
    Co-Authors: Lancelot P.m.g.j., De Breuker R.
    Abstract:

    This paper summarises a conceptual study regarding a passively actuated spoiler for Gust Load alleviation. The design of such system is intended to limit the use of computers, sensors and actuators to operate the device. The study mainly relies on using Theodorsen’s unsteady flow theory for a typical airfoil section. To cope with the limitations of this type of model for spoiler aerodynamic, corrections are brought from unsteady high fidelity flow simulations by means of transfer functions. The outcome is a 2D aeroelastic model with three degrees of freedom. It describes the spoiler contribution to the overall aeroelastic behaviour of the airfoil in the event of a Gust encounter. Results show that the spoiler can help to reduce Loads passively, but requires to be retracted with an active system to work properly.Aerospace Structures & Computational Mechanic

Chu Q. P. - One of the best experts on this subject based on the ideXlab platform.

  • Active Gust Load alleviation of high-aspect ratio flexible wing aircraft
    'American Institute of Aeronautics and Astronautics (AIAA)', 2018
    Co-Authors: Ferrier, Yvonne L., Nguyen, Nhan T., Ting Eric, Chaparro Daniel, Wang Xuerui, De Visser C.c., Chu Q. P.
    Abstract:

    This paper presents a novel active Gust Load alleviation approach within a multi-objective flight control framework developed by NASA for a flexible wing aircraft. The aircraft model is based on the NASA Generic Transport Model (GTM). The wing structures incorporate an aerodynamic control surface known as the Variable Camber Continuous Trailing Edge Flap (VCCTEF). Previous work already showed the ability of the VCCTEF to perform aeroelastic mode suppression, drag minimization and maneuver Load alleviation in a multi-objective flight control framework. In this paper, the multi-objective flight control framework is extended to include active Gust Load alleviation. A Linear-Quadratic Gaussian (LQG) controller is augmented with Model Reference Adaptive Control (MRAC) to provide active Gust Load alleviation. Disturbance estimation is done using an Extended State Observer (ESO) to support the design of the active Gust Load alleviation controller. The results demonstrate the potential of active Gust Load alleviation within a multi-objective flight control framework for a high-aspect ratio flexible wing aircraft embodied with the VCCTEF.Control & Simulatio

  • Flexible Aircraft Gust Load Alleviation with Incremental Nonlinear Dynamic Inversion
    'American Institute of Aeronautics and Astronautics (AIAA)', 2018
    Co-Authors: Wang X., Chu Q. P., Van Kampen E., De Breuker R.
    Abstract:

    In this paper, an Incremental Nonlinear Dynamic Inversion (INDI) controller isdeveloped for the flexible aircraft Gust Load alleviation (GLA) problem. First, a flexible aircraft model captures both inertia and aerodynamic coupling effects between flight dynamics and structural vibration dynamics is presented. Then an INDI GLA controller is designed for this aircraft model based on sensor measurements and the Kalman filter online estimation. Besides, the fifth order Padé approximation is used to model the pure time delay in the state estimation. Furthermore, simulations of the flexible aircraft flying through various spatial turbulence and Gust fields demonstrate the effectiveness of the proposed controller on rigid-body motion regulation, vertical Load alleviation, wing root bending moment reduction and elastic modes suppression. Additionally, numerical perturbation tests and a Monte-Carlo study show the robustness of the proposed controller to aerodynamic model uncertainties

Chao Yang - One of the best experts on this subject based on the ideXlab platform.

  • Gust Load Alleviation including Geometric Nonlinearities Based on Dynamic Linearization of Structural ROM
    Hindawi Limited, 2019
    Co-Authors: Chao Yang, Changchuan Xie, Yang Meng
    Abstract:

    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

  • Gust Load alleviation wind tunnel tests of a large aspect ratio flexible wing with piezoelectric control
    Chinese Journal of Aeronautics, 2017
    Co-Authors: Changchuan Xie, Chao Yang
    Abstract:

    Abstract An active control technique utilizing piezoelectric actuators to alleviate Gust-response Loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibration control of engineering structures. In this paper, piezoelectric materials further attempt to suppress the vibration of the aeroelastic wing caused by Gust. The motion equation of the flexible wing with piezoelectric patches is obtained by Hamilton’s principle with the modal approach, and then numerical Gust responses are analyzed, based on which a Gust Load alleviation (GLA) control system is proposed. The Gust Load alleviation system employs classic proportional-integral-derivative (PID) controllers which treat piezoelectric patches as control actuators and acceleration as the feedback signal. By a numerical method, the control mechanism that piezoelectric actuators can be used to alleviate Gust-response Loads is also analyzed qualitatively. Furthermore, through low-speed wind tunnel tests, the effectiveness of the Gust Load alleviation active control technology is validated. The test results agree well with the numerical results. Test results show that at a certain frequency range, the control scheme can effectively alleviate the z and x wingtip accelerations and the root bending moment of the wing to a certain extent. The control system gives satisfying Gust Load alleviation efficacy with the reduction rate being generally over 20%.

  • Gust response analysis and wind tunnel test for a high aspect ratio wing
    Chinese Journal of Aeronautics, 2016
    Co-Authors: Yi Liu, Changchuan Xie, Chao Yang, Jialin Cheng
    Abstract:

    A theoretical nonlinear aeroelastic response analysis for a flexible high-aspect ratio wing excited by harmonic Gust Load is presented along with a companion wind tunnel test. A multidisciplinary coupled numerical calculation is developed to simulate the flexible model wing undergoing Gust Load in the time domain via discrete nonlinear finite element structural dynamic analysis and nonplanar unsteady vortex lattice aerodynamic computation. A dynamic perturbation analysis about a nonlinear static equilibrium is also used to determine the small perturbation flutter boundary. A novel noncontact 3-D camera measurement analysis system is firstly used in the wind tunnel test to obtain the spatial large deformation and responses. The responses of the flexible wing under different static equilibrium states and frequency Gust Loads are discussed. The fair to good quantitative agreements between the theoretical and experimental results demonstrate that the presented analysis method is an acceptable way to predict the geometrically nonlinear Gust response for flexible wings.

  • Dynamic Gust Load Analysis for Rotors
    Hindawi Limited, 2016
    Co-Authors: Yuting Dai, Chao Yang, Linpeng Wang, Xintan Zhang
    Abstract:

    Dynamic Load of helicopter rotors due to Gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural Load for a rotor under the impulse Gust and slope-shape Gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic Gust Load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse Gust with the speed of 2m/s increases twice to the one without Gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect

Stanford, Bret K. - One of the best experts on this subject based on the ideXlab platform.

  • Optimal Aircraft Control Surface Layouts for Maneuver and Gust Load Alleviation
    2020
    Co-Authors: Stanford, Bret K.
    Abstract:

    The goal of this work is to conduct aeroservoelastic optimization of a high aspect ratio transport wingbox with distributed control surfaces along the trailing edge. The control surfaces are utilized for both quasi-steady maneuver Load alleviation (MLA) and unsteady Gust Load alleviation (GLA). The optimizer dictates the sizing details of the wingbox, the steady and unsteady control surface rotations, and also the control surface layout. Layout design variables specifically dictate which control surfaces to retain, and which to remove. The objective function is to minimize the sum of the actuator weight and the structural weight, with several imposed constraints related to structural failure and actuator saturation. The optimizers preferences with regards to control surface layout for MLA are in strong contrast to GLA-driven designs. The GLA-driven design space also suffers from local minima not evident in the MLA space

  • Gradient-Based Aeroservoelastic Optimization with Static Output Feedback
    2019
    Co-Authors: Stanford, Bret K.
    Abstract:

    Static output feedback considers an optimal low-order feedback matrix which directly connects the sensors to the control inputs. This work demonstrates the numerical techniques needed to compute the analytical gradient of the optimal feedback matrix with respect to design variables, which may then be used for gradient-based optimization. The derivatives are demonstrated for aeroservoelastic optimization under a series of closed- loop Gust Load alleviation constraints, considering a continuous stochastic Gust Load applied to a transport vehicle configuration, among other design constraints such as utter and maneuver Loads. The optimal trade-o s between passive Load alleviation and active Load alleviation for static output feedback are compared with those from full-state feedback, which may be considered an upper-bound for effective sensor-based control

  • Performance Enhancement of the Flexible Transonic Truss-Braced Wing Aircraft Using Variable-Camber Continuous Trailing-Edge Flaps
    2019
    Co-Authors: Waite, Josiah M., Stanford, Bret K., Bartels, Robert E.
    Abstract:

    Aircraft designers are to a growing extent using vehicle flexibility to optimize performance with objectives such as Gust Load alleviation and drag minimization. More complex aerodynamically optimized configurations may also require dynamic Loads and perhaps eventually flutter suppression. This paper considers an aerodynamically optimized truss-braced wing aircraft designed for a Mach 0.745 cruise. The variable camber continuous trailing edge flap concept with a feedback control system is used to enhance aeroelastic stability. A linearized reduced order aerodynamic model is developed from unsteady Reynolds averaged Navier-Stokes simulations. A static output feedback controller is developed from that model. Closed-loop simulations using the reduced order aerodynamic model show that the controller is effective in stabilizing the vehicle dynamics

  • Aeroservoelastic Optimization under Stochastic Gust Constraints
    2018
    Co-Authors: Stanford, Bret K.
    Abstract:

    This work considers the aeroservoelastic optimization of a highly flexible transport aircraft wingbox with several control surfaces distributed along the trailing edge. The steady deflections of the control surfaces are designed to alleviate static maneuver Loads, while the unsteady deflections are designed to alleviate stochastic continuous Gust disturbances. Spatially-detailed unsteady stochastic stress and panel buckling constraints are formulated via modal acceleration, and by methods to locate the most-probable failure point along an equal-probability hypersurface. For the case considered here, it is found that the inclusion of such Gust constraints during optimization presents a sizable structural mass penalty. In some cases, this mass penalty can be completely recovered with controlled Gust Load alleviation

Xiong Juntao - One of the best experts on this subject based on the ideXlab platform.

  • Simulation and Modeling of Flow Generated by Gust Generator in a Wind Tunnel
    2020
    Co-Authors: Cramer, Nicholas B., Nhan Nguyen, Xiong Juntao
    Abstract:

    A computational study of a Gust field generated by a Gust generator in a low-speed wind tunnel. The Gust generator is designed for the University of Washington Aeronautical Laboratory (UWAL) Kirsten wind tunnel for a Gust Load alleviation (GLA) control experiment of a Common Research Model (CRM) flexible wing utilizing the Variable Camber Continuous Trailing Edge Flap (VCCTEF). The Gust generator comprises four horizontal NACA 0015 Gust generator vanes placed upstream of the test section. Computational fluid dynamics simulations using a two-dimensional (2D) Unsteady-Reynolds-Averaged-Navier-Stokes (URANS) with k- Shear Stress Transport (SST) turbulence model provide detailed time-resolved information about the generated flow by the Gust generator under prescribed sinusoidal motion. The characteristics of the induced flow by the Gust generator are analyzed. A Gust propagation model of the Gust field is investigated. An unsteady lift model is developed using a varying-fidelity approach which includes a 2D interference aerodynamic model of the combined Gust generator-wing system. The computed integrated unsteady lift is compared to experimental data for validation of the unsteady lift model. Both the amplitude and transport delay are found to be accurately captured by the unsteady lift model

  • Progress on Gust Load Alleviation Wind Tunnel Experiment and Aeroservoelastic Model Validation for a Flexible Wing with Variable Camber Continuous Trailing Edge Flap System
    2020
    Co-Authors: Xiong Juntao, Nguyen Nhan, Jackson Joseph, Hashemiz Kelley, Boskovic Jovan, Drew Michael, Wise Richard, Cramery Nicholas, Shultz Adam, Livne Eli
    Abstract:

    This paper discusses a wind tunnel experiment of active Gust Load alleviation of a flexible wing which took place at University of Washington (UW) in 2019. The experiment performed under a NASA SBIR contract with Scientific Systems Company, Inc (SSCI). The objective of the experiment is to demonstrate active controls of the Variable Camber Continuous Trailing Edge Flap (VCCTEF) system for Gust Load alleviation and real-time drag optimization. The wind tunnel model is a 8.2% sub-scale Common Research Model (CRM) wing. The wing structure is designed to provide a substantial degree of flexibility to represent that of a modern high-aspect ratio wing. Eight active control surfaces are employed in the VCCTEF. A new Gust generator system was designed and installed by UW under a sub-contract with SSCI. The first test entry started in July 2019 and ended in September 2019. During this test entry, many significant issues were found with the hardware and software. The significant issues with the servos prevented the test objective from being completed. A follow-up second test entry in 2020 is being planned. The wing system is being repaired by SSCI. This paper reports on the progress of this experimental effort and the aeroservoelastic (ASE) model validation which was conducted during the test entry

  • Multi-Objective Gust Load Alleviation Control Designs for an Aeroelastic Wind Tunnel Demonstration Wing
    2020
    Co-Authors: Drew, Michael C., Cramer, Nicholas B., Xiong Juntao, Nguyen, Nhan T., Hashemi, Kelley E.
    Abstract:

    This paper presents several control and Gust disturbance estimation techniques applied to a mathematical model of a physical flexible wing wind tunnel model used in ongoing tests at the University of Washington Aeronautical Laboratory's Kirsten Wind Tunnel. Three methods of Gust disturbance estimation are presented, followed by three control methods: LQG, Basic Multi-Objective (BMO), and a novel Multi-Objective Prediction Correction (MOPC) controller. The latter of which augments a multi-objective controller, and attempts to correct for errors in the disturbance estimate. A simplified linear simulation of the three controllers is performed and a simple MIMO stability and robustness assessment is performed. Then, the same controllers are simulated in a higher fidelity Simulink environment that captures sampling, saturation and noise effects. This preliminary analysis indicates that the BMO controller provides the best performance and largest stability margins