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ORBi Open Repository and Bibliography (327.418 recursos)

In may 2007, the ULg's Administrative Board (joined in June 2007 by the FUSAGx) decided to create an institutional repository and defined a strong institutional self-archiving policy to increase the visibility, accessibility and impact of the University's publications (Board's decision). This decision led to the official launch, in November 2008, of the ORBi platform including both the Academic Bibliography and the Institutional Repository of the Wallonia-Europe University Academy.

Engineering, computing & technology => Aerospace & aeronautics engineering

Mostrando recursos 61 - 80 de 95

  1. Unsteady pressure distributions on a 4:1 rectangular cylinder: comparison of numerical and experimental results using decomposition methods.

    Guissart, Amandine; Andrianne, Thomas; Dimitriadis, Grigorios; Terrapon, Vincent
    Detached flows around bluff bodies are ubiquitous in civil engineering applications. In this work, the flow around a static 4:1 rectangular cylinder at moderate Reynolds number and at different angles of incidence is studied using both Experimental Fluid Dynamics (EFD) and Computational Fluid Dynamics (CFD). Typically, the integration of EFD and CFD allows a better understanding of the flow of interest by leveraging the complementary of their respective outputs. However, the comparison of computational and experimental results is an important but difficult step of this integration, particularly in the case of local quantities related to unsteady flows. In this work, decomposition methods are used...

  2. System-based approaches for structural optimization of flexible mechanisms

    Tromme, Emmanuel; Held, Alexander; Duysinx, Pierre; Bruls, Olivier
    Peer reviewed

  3. Freeplay-induced limit cycle oscillation mitigation using linear and nonlinear tuned vibration absorbers

    Verstraelen, Edouard; Kerschen, Gaëtan; Dimitriadis, Grigorios
    Structural nonlinearities such as freeplay in control surface bearings and actuators or in connections between wings and external payloads sometimes lead to aeroelastic limit cycle oscillations at airspeeds lower than the linear flutter speed of the aircraft. In parallel, numerous studies demonstrated the potential of linear and nonlinear tuned vibration absorbers to increase the flutter speed of linear and continuously hardening aeroelastic systems such as two-degree- of-freedom wings or long span bridges. In this work, the effect of linear and nonlinear tuned vibration absorbers is studied on a wing with pitch plunge and control surface deflection degrees of freedom and...

  4. PIV-based estimation of unsteady loads on a flat plate at high angle of attack using momentum equation approaches

    Guissart, Amandine; Bernal, Luis; Dimitriadis, Grigorios; Terrapon, Vincent
    Peer reviewed

  5. Flutter and limit cycle oscillation suppression using linear and nonlinear tuned vibration absorbers

    Verstraelen, Edouard; Kerschen, Gaëtan; Dimitriadis, Grigorios
    Aircraft are more than ever pushed to their limits for performance reasons. Consequently, they become increasingly nonlinear and they are more prone to undergo aeroelastic limit cycle oscillations. Structural nonlinearities affect aircraft such as the F-16, which can undergo store-induced limit cycle oscillations (LCOs). Furthermore, transonic buzz can lead to LCOs because of moving shock waves in transonic flight conditions on many aircraft. This study presents a numerical investigation of passive LCO suppression on a typical aeroelastic system with pitch and plunge degrees of freedom and a hardening stiffness nonlinearity. The absorber used is made of a piezoelectric patch glued to...

  6. Assessment of the fluid-structure interaction capabilities for aeronautical applications of the open-source solver SU2.

    Sanchez, Ruben; Kline, Heather; Thomas, David; Variyar, Anil; Righi, Marcello; Economon, Thomas; Alonso, Juan; Palacios, Rafael; Dimitriadis, Grigorios; Terrapon, Vincent
    Peer reviewed

  7. Robust mission design using invariant manifolds

    Dell'Elce, Lamberto; Baresi, Nicola; Kerschen, Gaëtan; Scheeres, Daniel J.
    Uncertainties in the dynamical system affect all real-life applications in astrodynamics. This is particularly true for satellites orbiting about small bodies owing to their irregular shapes and to the difficulties in characterizing their physical properties at the early stages of a dedicated spacecraft mission. Hence, accommodating uncertainty in the orbital design process may be extremely beneficial for the success of the mission. Here, in a Lyapunov stability perspective, the properties of the invariant manifolds are exploited to generate regions of the phase space where the motion is guaranteed to evolve despite the uncertainties in the system parameters and navigation errors....

  8. Identification of complex nonlinearities using cubic splines with automatic discretization

    Dossogne, Tilàn; Noël, Jean-Philippe; Kerschen, Gaëtan
    One of the major challenges in nonlinear system identification is the selection of appropriate mathematical functions to model the observed nonlinearities. In this context, piecewise polynomials, or splines, offer a simple and flexible representation basis requiring limited prior knowledge. The generally-adopted discretization for splines consists in an even distribution of their control points, termed knots. While this may prove successful for simple nonlinearities, a more advanced strategy is needed for nonlinear restoring forces with strong local variations. The present paper specifically introduces a two-step methodology to select automatically the location of the knots. It proposes to derive an initial model,...

  9. Development of a unified model for flow-material interaction applied to porous charring ablators

    Coheur, Joffrey; Schrooyen, Pierre; Turchi, Alessandro; Magin, Thierry

  10. Nonlinear Robust Control for Satellite Formation Flying via Adaptive Second-Order Sliding Modes

    Cho, Hancheol; Kerschen, Gaëtan
    Peer reviewed

  11. Identification of non-stationary dynamical systems using multivariate ARMA models

    Bertha, Mathieu; Golinval, Jean-Claude
    Peer reviewed

  12. Design of microstructures using stress-based topology optimization

    Collet, Maxime; Bruggi, Matteo; Noël, Lise; Bauduin, Simon; Duysinx, Pierre
    This paper aims at designing microstructures using stress-based topology optimization. Most of the developments so far have been made for compliance design in various field of applications as reflected in the literature. The emergence of the new additive manufacturing techniques allows to consider porous material, such as lattice structures for instance, which ca be used for the design of structural components subject to various solicitations. Those components must account for the stress level to prevent failure everywhere in the microstructures and by extension the whole structure itself. This work proposes to design such microstructures using topology optimization with limitation on...

  13. Design of an experimental set-up to analyse compliant mechanisms used for the deployment of a panel

    Dewalque, Florence; Bruls, Olivier
    Due to their high complexity, compliant mechanisms require high-fidelity mechanical models to reach a detailed understanding of their characteristics and predict their actual behaviour in various situations. This work focuses on tape springs which are used as an alternative to common mechanisms composed of kinematic joints. They present several assets such as, among others, passive deployment and self-locking, but they are characterised by a highly nonlinear behaviour including buckling, the formation of folds and hysteresis. An experimental set-up is then designed to gather information on these phenomena, while in parallel an equivalent finite element model is developed. Quasi-static and dynamic tests...

  14. Influence of the inter‐stage coupling flexibility on the dynamics of multi‐stage rotors

    Nyssen, Florence; Golinval, Jean-Claude
    Peer reviewed

  15. Nonlinear analysis of compliant mechanisms: application to tape springs

    Dewalque, Florence; Bruls, Olivier
    Brief summary of the mechanical behaviour of tape springs. Main results obtained by the means of finite element models. Description of the experimental set-up and results. See the extended abstract for more details.

  16. Mechanical behaviour of tape springs used in the deployment of reflectors around a solar panel

    Dewalque, Florence; Collette, Jean-Paul; Bruls, Olivier
    Peer reviewed

  17. Mechanical behaviour of tape springs used in the deployment of reflectors around a solar panel

    Dewalque, Florence; Collette, Jean-Paul; Bruls, Olivier
    In order to increase the production of power on small satellites, large solar panels are commonly deployed and, in some cases, reflectors are added to improve the concentration factor on solar cells. In this work, reflectors are deployed by the means of compliant mechanisms known as tape springs. Their attractive characteristics are, among others, their passive behaviour, their self-locking capacity, their elastic deformations and their robustness. It is shown here through parametric studies that the behaviour of a tape spring is mainly governed by its geometry. Thus, for each specific application, its dimensions must be determined in order to minimise...

  18. Experimental Validation of Structural Damping Models for Tape Springs

    Dewalque, Florence; Bruls, Olivier
    The objective of this paper is to study the effect of structural dissipation on the dynamic response of tape springs using experimentally-validated finite element models. In order to reach this goal, an experimental set-up is built. It consists of two tape springs connected to a fixation support and a dummy panel. The data are collected through a force plate and a 3D motion analysis system. The post-treatment of the experimental results and a comparison with a finite element model show that the Kelvin-Voigt model gives a fair approximation of the structural damping for small oscillations, however, more advanced model should...

  19. Implementation of the blade element theory to investigate the aerodynamic performance of a ducted fan UAV

    Guissart, Amandine; Arendt, Dimitri; Terrapon, Vincent; Andrianne, Thomas

  20. Importance of structural damping in the dynamic analysis of compliant deployable structures

    Dewalque, Florence; Rochus, Pierre; Bruls, Olivier
    Peer reviewed

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