776 Works

Understanding and Modeling Nonlinear Behaviors in Aerospace Structures using Sine-Sweep Testing

Tilan Dossogne, Jean-Philippe Noel, Luc Masset, Gaetan Kerschen & Bart Peeters
During the design cycle of aircraft, the role played by the structural dynamicists consists in constructing a validated numerical model of the aircraft behavior under vibration. Model validation is performed experimentally, by correlating predicted and measured natural frequencies and mode shapes. This process has become standard in the aircraft industry; however, it relies throughout on the assumption of linearity of the structural vibrations, while it must be acknowledged that, today, test engineers are more and...

Highly-Nonlinear and Transient Structural Dynamics: a Review about Crashworthiness of Composite Aeronautical Structures

Eric Deletombe & David Delsart
This paper is a bibliographic review dealing with composite aircraft and rotorcraft crashworthiness. The paper focuses on structural aspects of large composite aircraft or rotorcraft parts (fuselage parts, barrels or larger parts). Material topics, such as the experimental characterization and numerical modelling of the dynamic behavior of composite materials, of composite joints (details) and of energyabsorbing components (elementary parts) are mentioned but not discussed in detail. More information about this topic can be found, for...

Study of Morphing Winglet Concepts Aimed at Improving Load Control and the Aeroelastic Behavior of Civil Transport Aircraft

Cedric Liauzun, Dominique Le Bihan, Jean-Michel David, Didier Joly & Bernard Paluch
Morphing is today widely studied in order to improve aircraft performance and thereby decrease their environmental footprint. This paper deals with the preliminary study of several morphing winglet concepts aimed at improving load control and aeroelastic behavior. The first step consisted in building and validating low-CPU-time-consuming but accurate aeroelastic models able to take into account aerodynamics, structural dynamics and flight mechanics, in order to handle free flexible aircraft. Aeroelastic state-space models have therefore been built...

A Review of Industrial Aeroelasticity Practices at Dassault Aviation for Military Aircraft and Business Jets

Eric Garrigues
Aircraft structure design is a complex industrial process that requires multidisciplinary analyzes and considerations in fields as diverse as aerodynamics, structure, materials and systems, as well as the right compromise between the constraints imposed by these different fields, in order to meet the overall performances required for aircraft. In the field of business jets and military aircraft, given the research into ever more efficient aerodynamic formulas, the constant desire to design \"as light as possible\",...

Vibration Mitigation Based on Nonlinear Absorbers

Cyrille Stephan, Giuseppe Pennisi & Guilhem Michon
The design of vibration absorbers is a challenging task for complex real-life structures. Although several technological solutions have now reached maturity, a need for better efficiency in terms of added mass, roadband frequency range and level of reduction requires the study of new ideas and concepts coming from nonlinear dynamics. In this paper an introduction to a class of absorbers called Nonlinear Energy Sinks (NES) is proposed to highlight their potential for vibration mitigation. After...

Advances in Parametric and Model-Form Uncertainty Quantification in Canonical Aeroelastic Systems

Jean-Camille Chassaing, Christian Nitschke, Angela Vincenti, Paola Cinnella & Didier Lucor
Uncertainty quantification is going to play a crucial role in the aeroelastic design and optimization of aircraft. Stochastic aeroelastic models are currently being considered to account for manufacturing tolerance in material properties, variability in flight conditions or uncertainty in the aeroelastic model itself. In this paper, some challenging issues in the development of efficient and robust stochastic solvers are reported within the framework of canonical aeroelastic systems. First, independent or correlated parametric uncertainties are propagated...

On the Validation and Use of High-Fidelity Numerical Simulations for Gust Response Analysis

Fabien Huvelin, Sylvie Dequand, Arnaud Lepage & Cedric Liauzun
Specific gust response is considered as one of the most important loads encountered by an aircraft. The Certification Specification (CS) 25, defined by the European Aviation Safety Agency (EASA), and the Federal Aviation Regulations (FAR) 25, defined by the Federal Aviation Administration (FAA), describe the critical gusts that an aircraft must withstand. They must be analyzed for a large range of flight points (Altitude and Equivalent Air speed) and mass configurations. For some load cases,...

Descent Methods for Design Optimization under Uncertainty

Fabrice Poirion & Quentin Mercier
AerospaceLab Journal, Issue 14, September 2018; ISSN: 2107-6596

Modelling the Damping at the Junction between Two Substructures by Non-Linear Meta-Models

Veronique Kehr-Candille
AerospaceLab Journal, Issue 14, September 2018; ISSN: 2107-6596

Overview of the Aeroelastic Capabilities of the elsA Solver within the Context of Aeronautical Engines

Alain Dugeai, Yann Mauffrey, Antoine Placzek & Simon Verley
AerospaceLab Journal, Issue 14, September 2018; ISSN: 2107-6596

A Comprehensive Load Process at the DLR Definition, Analysis, and Experimental Evaluation

Wolf Kruger, Pier Davide Ciampa, Martin Geier, Thiemo Kier, Thomas Klimmek, Dieter Kohlgruber, Per Ohme, Kristof Risse & Julian Schwinn
AerospaceLab Journal, Issue 14, September 2018; ISSN: 2107-6596

Aeroelasticity and Structural Dynamics

Cedric Liauzun & Nicolas Piet-Lahanier
AerospaceLab Journal, Issue 14, September 2018; ISSN: 2107-6596

Aeroelasticity and Structural Dynamics

Liauzun Et Al.
AerospaceLab Journal, Issue 14, September 2018; ISSN: 2107-6596

Stability Analysis of a Set of Uncertain Large-Scale Dynamical Models with Saturations

Pierre Vuillemin, Fabrice Demourant & Charles Poussot-Vassal
From a sparse set of large-scale Linear Time Invariant (LTI) dynamical models, a methodology to generate a low-order parameter-dependent and uncertain model, with guaranteed bounds on the approximation error is firstly obtained using advanced approximation and interpolation techniques. Secondly, the stability of the aforementioned model, represented as a Linear Fractional Representation (LFR) and subject to actuator saturation and dynamical uncertainties, is addressed through the use of an irrational multiplier-based Integral Quadratic Constraint (IQC) approach. The...

Surrogate Assisted Computation of the Parametric Safety Margin for a Flexible Launcher

Atul Kamath, Prathyush P Menon, Martine Ganet-Schoeller, Guillaume Maurice & Samir Bennani
In order to assess the robustness of dynamical systems, an approach is to demarcate the uncertain parameter space as safe set and unsafe set. Unsafe set represents the region within which the system lacks the required level of performance, or even loses its stability. However, determining the minimum distance metric for the unsafe set from the nominal operating point, the so-called parametric safety margin, for a higher dimensional dynamical system is not trivial and is...

Structured Control for Future European Launchers

Martine Ganet-Schoeller, Jean Desmariaux & Clement Combier
Control of a flexible launcher during the atmospheric flight phase is a highly challenging control problem involving multiple and concurrent design requirements: stability (stabilization of unstable rigid dynamics, sloshing modes and flexible structural modes), performance (guidance tracking, structural load minimization) and robustness (physical parameter uncertainties and accommodation to multiple vehicle configurations) on a non-stationary system. This paper focuses on co-funded AG/CNES research activities on the development of an advanced modular control strategy using recent advances...

Anti-Windup Algorithms for Pilot-Induced-Oscillation Alleviation

Isabelle Queinnec, Sophie Tarbouriech, Jean-Marc Biannic & Christophe Prieur
The paper deals with the development of anti-windup schemes and related numerical oriented tools. The objective is then to design anti-windup compensators to guarantee stability and performance for some particular classes of nonlinear actuators presenting both magnitude and rate saturations. The lateral flying case for a civil aircraft undergoing aggressive maneuvering by the pilot is addressed. A complete methodology including theoretical conditions and associated toolbox is then proposed and compared to solutions based on anti-PIO...

Robustness Margins for Linear Parameter Varying Systems

Ann-Kathrin Schug, Peter Seiler & Harald Pfifer
An approach for extending classical robustness margins to linear parameter varying (LPV) systems is presented. LPV systems are often used to model aircraft dynamics that are highly dependent on the operating conditions such as altitude and airspeed. Classical gain and phase margins are evaluated in the frequency domain and therefore cannot be applied to LPV systems. The proposed approach is based on a time-domain interpretation for disk margins. Specifically, a norm bounded linear time invariant...

Stability Analysis by a New Algorithmic Approach Based on Integral Quadratic Constraints : Application to an Aircraft Benchmark

Fabrice Demourant
To analyze a non-linear, uncertain and time-varying closed loop representing a fighter aircraft model interconnected with a control law, an Integral Quadratic Constraint (IQC) approach has been used. This approach is particularly interesting for two reasons. The first one is that it is possible with the same stability criterion to analyze a large class of stability problems. The second reason is that the stability criterion is based on frequency dependent inequalities (FDI). Usually, the Kalman-...

Randomized and Robust Methods for Uncertain Systems using R-RoMulOC, with Applications to DEMETER Satellite Benchmark

Mohammadreza Chamanbaz, Fabrizio Dabbene, Dimitri Peaucelle & Christelle Pittet
R-RoMulOC is a freely distributed toolbox aimed at making easily available to the users various optimization-based methods for dealing with uncertain systems. It implements both deterministic LMI-based results, which provide guaranteed performance for all values of the uncertainties, and probabilistic randomization-based approaches, which guarantee performance for all values of the uncertainties except for a subset with arbitrary small probability measure. The paper is devoted to the description of these two approaches for analysis and control...

Gain-Scheduled H Loop-Shaping Autopilot Design for Spin-Stabilized Canard-Guided Projectiles

Florian Seve, Spilios Theodoulis, Philippe Wernert, Michel Zasadzinski & Mohamed Boutayeb
This article is dedicated to the design of a complete guidance control system for the roll/pitch/yaw-channels of a 155 mm dual-spin projectile equipped with nosemounted trajectory correction canards. The projectile airframe parameter-dependent nonlinear model including aerodynamic and actuator/sensor uncertainty descriptions is given and the subsequently computed linearized models necessary for autopilot design are presented. The itch/yaw-channel dynamics linearized system is useful for highlighting important properties specific to these dynamics, in particular in relation with the...

Nonlinear Structured H Controllers for Parameter- Dependent Uncertain Systems with Application to Aircraft Landing

Jean-Marc Biannic, Clement Roos & Jeremy Lesprier
Anew design methodology inspired by dynamic inversion techniques is proposed in this paper. It combines partially linearizing inner-loops with structured and robust outer-loops, which are designed using a non-smooth multi-model H optimization approach. The proposed methodology also includes a robustness analysis scheme providing worst-case configurations, which are then used to enrich the bank of design models and thus iteratively improve the robustness properties of the designed outerloops. Our approach is successfully tested on a realistic...

The H Control Problem is Solved

Pierre Apkarian & Dominikus Noll
The H control problem was posed by G. Zames in 1981 [1], and various attempts to address it had been made over the years. Ultimately, in 2006, the authors presented their solution, which is based on a tailored non-smooth optimization technique [2]. In this treatise we present the rationale of H control, give a brief history, and recall the milestones reached before our 2006 solution. We clarify why our novel approach is welcomed in the...

Design and Validation of Aerospace Control Systems An overview on methods tools

Jean-Marc Biannic & Clement Roos
Since their early development in the 1970s with the introduction of fly-by-wire technology, control systems have considerably evolved. Thanks to powerful on-board computers whose capacities have undergone an exponential growth over the past thirty years, together with the development of enhanced sensors and actuators, the complexity of aerospace control systems is almost no longer bounded today. This is true at least from a technological viewpoint. Control engineers should, however, keep in mind that there are...

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