64 research outputs found

    Ein Windkanalmodell zur Untersuchung von Morphing-Technologien und natürlicher Laminarität

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    Die Entwicklung energieeffizienter Flugzeuge ist ein Schwerpunkt der europäischen Luftfahrtforschung. Für Kurz- und Mittelstreckenflugzeuge, die üblicherweise 30 bis 100 Passagiere befördern, wurde im Rahmen des EUProgramms IADP Regional Aircraft ein Flügel entworfen, der zur Erreichung höherer Effizienz verschiedene Technologien integriert: - hohe Oberflächengüte zur Erzeugung der natürlichen Laminarität (Natural Laminar Flow – NLF), - elastisch verformbare, morphende Vorflügel, die eine spaltfreie Hochauftriebskonfiguration ermöglichen, - morphende Klappen, um Belastungen des Flügels aerodynamisch zu beeinflussen, - ein Winglet und ein Wingtip mit integrierten Klappen zur Lastbeeinflussung

    Experimental Results of a Fluid Actuated Morphing Winglet Trailing Edge

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    Designing active control surface technology into thin regions of aircraft wings is challenging due to small available volumes. To be able to do so is potentially beneficial to enable more efficient wing designs using morphing for e.g. load alleviation. This paper details a winglet trailing edge surface composed of fluid actuated morphing unit structures (FAMoUS) that enable control surface deflections under the corresponding aerodynamic hinge moments. These FAMoUS actuators are comprised of elastomer and metallic stiffeners, which under internal pressure from a fluid exert displacement and force and thus output work. Combining these unit structures in a bimorph setup a trailing edge control surface is build. This paper outlines the design, finite element analyses and manufacturing process of a demonstrator with 1 m span-width. These finite element analyses consist of detailed tuned material parameters obtained from testing on the individual unit structure tests as well as the inclusion of hydrostatic fluid elements to determine effective stiffnesses from the pressure-volume relationship between the housing structure and internal fluid. Manufacturing of the demonstrator is conducted using composite fabrication and machining techniques to ensure that the demanding tolerances and surface qualities are to be maintained. The structural part of the demonstrator is joint with an actuating system, where in combination wíth feedback sensors position control is achieved. The setup of the actuating system is introduced, elucidating the hydraulic system and the overall control design. Experimental results of tests are presented, starting with calibration of the feedback system with an external measurement, also clarifying deflection uniformity along the span of the demonstrator. Further results of deflection performance and deflection rate are presented and compared to the predictions derived from the finite element analyses. The findings are discussed and contextualized. A summary of the results is given and an outlook on the way forward is presented

    Review of Adaptive Shock Control Systems

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    Drag reduction plays a major role in future aircraft design in order to lower emissions in aviation. In transonic flight, the transonic shock induces wave drag and thus increases the overall aircraft drag and hence emissions. In the past decades, shock control has been investigated intensively from an aerodynamic point of view and has proven its efficacy in terms of reducing wave drag. Furthermore, a number of concepts for shock control bumps (SCBs) that can adapt their position and height have been introduced. The implementation of adaptive SCBs requires a trade-off between aerodynamic benefits, system complexity and overall robustness. The challenge is to find a system with low complexity which still generates sufficient aerodynamic improvement to attain an overall system benefit. The objectives of this paper are to summarize adaptive concepts for shock control, and to evaluate and compare them in terms of their advantages and challenges of their system integrity so as to offer a basis for robust comparisons. The investigated concepts include different actuation systems as conventional spoiler actuators, shape memory alloys (SMAs) or pressurized elements. Near-term applications are seen for spoiler actuator concepts while highest controllability is identified for concepts several with smaller actuators such as SMAs

    X-ray computed tomography method for macroscopic structural property evaluation of active twist composite blades

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    This paper describes an evaluation of the structural properties of the next-generation active twist blade using X-ray computed tomography (CT) combined with digital image processing. This non-destructive testing technique avoids the costly demolition of the blade structure. The CT scan covers the whole blade region, including the root, transition, and tip regions as well as the airfoil blade regions, in which there are spanwise variations in the interior structural layout due to the existence of heavy instrumentation. The three-dimensional digital image data are processed at selected radial stations, and finite element beam cross-section analyses are conducted to evaluate the structural properties of the blade at the macroscopic level. The fidelity of the digital blade model is first assessed by correlating the estimated blade mass with the measured data. A separate me- chanical measurement is then carried out to determine the representative elastic properties of the blade and to verify the predicted results. The agreement is found to be good to excellent for the mass, elastic axis, flap bending, and torsional rigidity. Finally, a sensitivity analysis is conducted to clarify the impact of modeling the sensor and actuator cables, nose weight, and manufacturing im- perfections on the structural properties of the blade

    X-ray computed tomography method for macroscopic structural property evaluation of active twist composite blades

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    This paper describes an evaluation of the structural properties of the next-generation active twist blade using X-ray computed tomography (CT) combined with digital image processing. This non-destructive testing technique avoids the costly demolition of the blade structure. The CT scan covers the whole blade region, including the root, transition, and tip regions as well as the airfoil blade regions, in which there are spanwise variations in the interior structural layout due to the existence of heavy instrumentation. The three-dimensional digital image data are processed at selected radial stations, and finite element beam cross-section analyses are conducted to evaluate the structural properties of the blade at the macroscopic level. The fidelity of the digital blade model is first assessed by correlating the estimated blade mass with the measured data. A separate me- chanical measurement is then carried out to determine the representative elastic properties of the blade and to verify the predicted results. The agreement is found to be good to excellent for the mass, elastic axis, flap bending, and torsional rigidity. Finally, a sensitivity analysis is conducted to clarify the impact of modeling the sensor and actuator cables, nose weight, and manufacturing im- perfections on the structural properties of the blade

    Eine adaptive Primärfeder als Teil des Einzelradlaufwerks des Next Generation Trains

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    Der Entwurf von energieeffizienten und schnellen Personenzügen ist Bestandteil des Projektes "Next Generation Train" des DLR. Neben Leichtbau ist ein Einzelradlaufwerk mit individuell angetriebenen Rädern wesentlicher Bestandteil des Konzeptes. Die Primärfeder als Komponente des Einzelradlaufwerks ist als aktives Element ausgeführt, was aktive Schwingungsbeeinflussung ermöglicht. Die Motivation der Auslegung als adaptive Primärfeder wird dargelegt und der Entwurfsprozess für die Federstruktur vorgestellt. Ausgehend von den Entwurfsrandbedingungen wird exemplarisch die Variante einer Glasfaserverbundfeder mit piezokeramischen Aktoren gezeigt. Die zur Schwingungsbeeinflussung nutzbaren Verformungen werden diskutiert und das Regelungskonzept erläutert. Abschließend wird ein Ausblick auf die weiter geplanten Arbeiten gegeben

    Active Primary Spring for the Next Generation Train

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    In this paper the design of an active primary spring for a single-wheel single running-gear railroad carriage is discussed. The setup is based on a leaf-spring design, which is implemented as fibre-composite part, combined with piezo-ceramic stack-actuators, enabling to dynamically influence the contact between wheel and rail. The motivation of the design as active component is discussed and the process of dimensioning of the leaf-spring is introduced. Final dimensions and active properties of the primary springs are given and discussed. An approach to a control scheme for first tests is presented as well as results from first dynamic tests with a downscaled prototype. The paper closes with the outlook on tests and simulations which elucidate the integration into the concept of the mechatronic running gear
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