Technologien zur Analyse und Reduktion von Lasten an Verkehrsflugzeugen (ATLAS2Hybrid/ReduLa): Schlussbericht

Die Bestimmung der auf das Flugzeug wirkenden Lasten sowie aeroelastische Stabilitätsanalysen gehören zu den Hauptaufgaben bei der Flugzeugentwicklung. Die Kenntnis der Lasten ist wichtig für den Entwurf und die Auslegung eines Flugzeugs, z. B. für die Dimensionierung der Struktur, beide Analysebereiche sind zulassungsrelevant. Im Airbus-geführten Lufo V-1-Vorhaben ATLAS2Hybrid war das DLR mit dem Eigenantrag ReduLa vertreten. Die Arbeiten befassten sich, unter den speziellen Aspekten der Lastanalyse und aeroelastischen Stabilitätsanalyse, mit dem Einsatz und der Bewertung neuer Technologien (wie z. B. der Verwendung neuer Werkstoffe für den Entwurf hochflexibler Flügel sowie der aktiven Lastreduktion), der Entwicklung neuer Berechnungsverfahren für Strukturdynamik (insbesondere unter Berücksichtigung von Flug- und Bodenlasten), Aerodynamik und Aeroelastik (Nutzung von CFD, Analysen im flugmechanischen Grenzbereich), sowie mit der Validierung von Verfahren durch Experimente, z. B. durch Standschwingversuche, Windkanalversuche und Flugversuche. Der Bericht ist der offizielle Schlussbericht des Vorhabens

A hybrid approach for the analysis of aircraft ground loads

This work presents a new process for the detailed assessment of the impact of aircraft ground maneuvers on local structural loads. The process is comprised of two core elements, a multibody simulation analysis and a subsequent direct transient response finite element analysis. The multibody simulation is used for the simulation of aircraft landing loads. These loads are then applied to an aircraft finite element model, via a direct transient response, for a more detailed analysis of the aircraft dynamic behavior at the desired points of interest. The process has been developed using landing simulations with three different finite element models of a 150-passenger aircraft. The objective of the current activities is to study the effect of major simulation and modelling parameters on the detailed aircraft dynamic response. In the paper, the process and detailed results are presented

Assessment of Dynamic Landing Loads by a Hybrid Multibody / Full Finite Element Simulation Approach

This paper describes a new process for the detailed assessment of the impact of aircraft ground manoeuvres on local structural loads. The process is comprised of two core elements, a multibody simulation analysis and a subsequent direct transient response finite element analysis. The multibody simulation is used for the simulation of aircraft landing loads. These loads are then applied to an aircraft finite element model, via a direct transient response, for a more detailed analysis of the aircraft dynamic behavior at the desired points of interest. The process has been developed using landing simulations of two reference aircraft with their corresponding finite element models. The objective of the current activities is to study the effect of major simulation and modelling parameters on the detailed aircraft dynamic response. In the paper, the process and the results of the parameter studies will be presented

A hybrid approach for the analysis of aircraft ground loads

This work presents a new process for the detailed assessment of the impact of aircraft ground maneuvers on local structural loads. The process is comprised of two core elements, a multibody simulation analysis and a subsequent direct transient response finite element analysis. The multibody simulation is used for the simulation of aircraft landing loads. These loads are then applied to an aircraft finite element model, via a direct transient response, for a more detailed analysis of the aircraft dynamic behavior at the desired points of interest. The process has been developed using landing simulations with three different finite element models of a 150-passenger aircraft. The objective of the current activities is to study the effect of major simulation and modelling parameters on the detailed aircraft dynamic response. In the paper, the process and detailed results are presented

Parametric Structural Modelling for Aeroelastic and Aeroacoustic Analyses of an Aircraft Rear Fuselage

For the development of numerical methods for aeroelastic analysis and vibration analyses on future aircraft configurations, representative reference models for the aerodynamics and the aircraft structure are necessary. Only very few models with a sufficient level of detail are publicly available. The DLR tool MONA is used for the for the generation of parametric aircraft models, i. e. finite element models and linear aerodynamic models, to realistically represent the global structural and aeroelastic dynamics of an aircraft. In the project, the focus was on the extension of the modelling capabilities of MONA to the generation of fuselage models of sufficient detail for aeroelastic and vibroacoustic analysis. Those models were then passed on to project partners for the respective analyses

Gaussian Entanglement of Formation

We introduce a Gaussian version of the entanglement of formation adapted to bipartite Gaussian states by considering decompositions into pure Gaussian states only. We show that this quantity is an entanglement monotone under Gaussian operations and provide a simplified computation for states of arbitrary many modes. For the case of one mode per site the remaining variational problem can be solved analytically. If the considered state is in addition symmetric with respect to interchanging the two modes, we prove additivity of the considered entanglement measure. Moreover, in this case and considering only a single copy, our entanglement measure coincides with the true entanglement of formation.Comment: 8 pages (references updated, typos corrected

The optimal cloning of quantum coherent states is non-Gaussian

We consider the optimal cloning of quantum coherent states with single-clone and joint fidelity as figures of merit. Both optimal fidelities are attained for phase space translation covariant cloners. Remarkably, the joint fidelity is maximized by a Gaussian cloner, whereas the single-clone fidelity can be enhanced by non-Gaussian operations: a symmetric non-Gaussian 1-to-2 cloner can achieve a single-clone fidelity of approximately 0.6826, perceivably higher than the optimal fidelity of 2/3 in a Gaussian setting. This optimal cloner can be realized by means of an optical parametric amplifier supplemented with a particular source of non-Gaussian bimodal states. Finally, we show that the single-clone fidelity of the optimal 1-to-infinity cloner, corresponding to a measure-and-prepare scheme, cannot exceed 1/2. This value is achieved by a Gaussian scheme and cannot be surpassed even with supplemental bound entangled states.Comment: 4 pages, 2 figures, revtex; changed title, extended list of authors, included optical implementation of optimal clone

Wind tunnel experiment with an EPP-wing to investigate aeroelastic effects of nonlinear elastic stiffnesses

Background: Nonlinear elastic, especially degressive, stiffnesses can reduce the wing root bending moment for design loadcases, while the cruise flight shape remains unchanged. Objective: The aim of the wind tunnel experiment is to show up the behaviour of a wing with a degressive stiffness. The tested wing is made of expanded polypropylene foam (EPP). Method: A flexural bending test is conducted to gain the bending stiffness of EPP for different densities and a wind tunnel test is performed to obtain the dependency between bending moment and deflection. The findings are compared to the results of an aeroelastic method based on a nonlinear elastic beam. Results: The bending stiffness of EPP material exhibit a nonlinear degressive stiffness. The foam wing has a softening characteristic for ascending loads. The numerical beam method for nonlinear elastic wings shows up a good agreement with the experiment and points out the load reducing effect of nonlinear structures

Strukturmodellierung und Lastanalyse eines Mittelstreckenflugzeugs im Projekt ALEGRO

Dieser Artikel beschreibt die Arbeiten, die vom DLR im Rahmen des Verbundvorhabens ALEGRO im nationalen Luftfahrtforschungs-programm durchgeführt wurden. Die disziplinübergreifenden Arbeitsinhalte umfassen die Erweiterung der Modellbildung um bessere Massenmodelle und für strukturelle Komponenten wie z. B. die Center Section, sowie eine Evaluierung der Nutzung von CFD/ CSM-Simulationen im Lastanalyseprozess. Die Entwicklungen des Projekts fließen in einen integrierten Lastanalyse- und Strukturentwurfsprozess ein und wurden in diesem Rahmen an dem Entwurf einer industrienahem Referenzkonfiguration verifiziert. Durch die enge Verzahnung von Lasten- und Entwurfsprozess zielen die Weiterentwicklungen im Projekt neben der Verbesserung der eigentlichen Lastanalyse auch auf eine Verkürzung des gesamten Entwurfsprozesses