TY - CHAP A1 - Mertens, Josef ED - Sobieczky, H. T1 - Certification of supersonic civil transports T2 - New design concepts for high speed air transport. - (Courses and lectures / International Centre for Mechanical Sciences ; 366) N2 - Since certification of Concorde new certification standards were introduced including many new regulations to improve flight safety. Most of these standards are to prevent severe accidents in the future which happened in the past (here: after Concorde’s certification). A new SCT has to fulfill these standards, although Concorde had none of these accidents. But accidents - although they sometimes occurred only for a specific aircraft type - have to be avoided for any (new) aircraft. Because of existing aircraft without typical accident types having demonstrated their reliability, they are allowed to go on based on their old certification; although sometimes new rules prevent accident types which are not connected to specific aircraft types - like e.g. evacuation rules. Anyway, Concorde is allowed to fly based on its old certification, and hopefully in the future will fly as safely as in the past. But a new SCT has to fulfill updated rules like any other aircraft, and it has to be “just another aircraft” [75]. KW - Noise Exposure KW - Evacuation Rule KW - Severe Accident KW - Certification Rule KW - Thermal Fatigue Testing Y1 - 1997 SN - 3-2118-2815-X U6 - https://doi.org/10.1007/978-3-7091-2658-5_6 SP - 97 EP - 103 PB - Springer CY - Wien [u.a.] ER - TY - CHAP A1 - Mertens, Josef ED - Sobieczky, H. T1 - Supersonic laminar flow T2 - New design concepts for high speed air transport. - (Courses and lectures / International Centre for Mechanical Sciences ; 366) N2 - Supersonic transports are very drag sensitive. Technology to reduce drag by application of laminar flow, therefore, will be important; it is a prerequisite to achieve very long range capability. In earlier studies it was assumed that SCTs would only become possible by application of laminar flow [376]. But today, we request an SCT to be viable without application of laminar flow in order to maintain its competitiveness when laminar flow becomes available for subsonic and supersonic transports. By reducing fuel burned, laminar flow drag reduction reduces size and weight of the aircraft, or increases range capability -whereas otherwise size and weight would grow towards infinity. Transition mechanisms from laminar to turbulent state of the boundary layer flow (ALT, CFI, TSI) function as for transonic transports, but at more severe conditions: higher sweep angles, cooled surfaces; higher mode instabilities (HMI) must at least be taken into account, although they may not become important below Mach 3. Hitherto there is a worldwide lack of ground test facilities to investigate TSI at the expected cruise Mach numbers between 1.6 and 2.4; in Stuttgart, Germany one such facility -a Ludwieg tube- is still in the validation phase. A quiet Ludwieg tunnel could be a favourable choice for Europe. But it will require a new approach in designing aircraft which includes improved theoretical predictions, usage of classical wind tunnels for turbulent flow and flight tests for validation. KW - Wind Tunnel KW - Flight Test KW - Supersonic Wind Tunnel KW - Parabolized Stability Equation Y1 - 1997 SN - 3-2118-2815-X U6 - https://doi.org/10.1007/978-3-7091-2658-5_18 SP - 275 EP - 290 PB - Springer CY - Wien [u.a.] ER - TY - JOUR A1 - Mertens, Josef T1 - Charakteristiken des Staub-Gas-Gemisches JF - Zeitschrift für angewandte Mathematik und Mechanik : ZAMM. 65 (1985), H. 4 Y1 - 1985 SN - 1521-4001 SP - T211 EP - T213 ER - TY - CHAP A1 - Mertens, Josef ED - Sobieczky, H. T1 - Son of Concorde, a technology challenge T2 - New design concepts for high speed air transport. - (Courses and lectures / International Centre for Mechanical Sciences ; 366) N2 - Concorde (Figure 9) is the only supersonic airliner which has been introduced into regular passenger service. It is still in service at British Airways and Air France without any flight accidents, and probably will stay in service for at least for ten more years. KW - Technology Challenge KW - Multidisciplinary Design Optimization KW - Specific Fuel Consumption KW - Engine Efficiency KW - Sonic Boom Y1 - 1997 SN - 3-2118-2815-X U6 - https://doi.org/10.1007/978-3-7091-2658-5_3 SP - 31 EP - 51 PB - Springer CY - Wien [u.a.] ER - TY - CHAP A1 - Mertens, Josef ED - Sobieczky, H. T1 - Aerodynamic multi point design challenge T2 - New design concepts for high speed air transport.- (Courses and lectures / International Centre for Mechanical Sciences ; 366) N2 - In the chapter “Son of Concorde, a Technology Challenge” one of the new challenges for a Supersonic Commercial Transport (SCT) is multi-point design for the four main design points: - supersonic cruise - transonic cruise - take-off and landing - transonic acceleration. KW - Drag Reduction KW - Pitching Moment KW - Leading Edge Vortex KW - Wave Drag KW - Variable Geometry Y1 - 1997 SN - 3-2118-2815-X U6 - https://doi.org/10.1007/978-3-7091-2658-5_4 SP - 53 EP - 67 PB - Springer CY - Wien [u.a.] ER - TY - BOOK A1 - Mertens, Josef T1 - Instationäre Strömungen von Gasen mit brennbaren Partikeln Y1 - 1983 N1 - Aachen, Techn. Hochschule, Diss., 1983 CY - Aachen ER - TY - CHAP A1 - Mertens, Josef T1 - Next steps envisaged to improve wing performance of commercial aircraft T2 - Aerodynamic drag reduction technologies : proceedings of the CEAS/DragNet European Drag Reduction Conference, 19–21 June 2000, Potsdam, Germany. - (Notes on numerical fluid mechanics ; 76) Y1 - 2001 SN - 3-540-41911-X (Print) SN - 978-3-540-45359-8 (Elektronisch) U6 - https://doi.org/10.1007/978-3-540-45359-8_26 SP - 246 EP - 255 PB - Springer CY - Berlin [u.a.] ER - TY - CHAP A1 - Mertens, Josef T1 - Reduction of aerodynamic drag (RaWid)-Status after the first year of the program T2 - New results in numerical and experimental fluid mechanics. - (Notes on numerical fluid mechanics ; 60) N2 - The technology programme “Reduction of aerodynamic drag (RaWid)” for high speed aerodynamics at Daimler-Benz Aerospace Airbus is sponsered by the German ministry for education, research and technology since July 1, 1995. Connected to this industrial programme are the cooperation programmes “MEGAFLOW” under leadership of the DLR and “Transition” by the DFG, and several contributions by DLR and universities. The programme is oriented towards technologies required for a MEGALINER which gains momentum by the ambitious plans for a new large Airbus A3XX. In the first year new technological steps were undertaken in theory, design and experiment. Some critical steps were verified by wing designs checked in wind tunnel tests. KW - Wind Tunnel KW - Aerodynamic Drag KW - Flight Test KW - Friction Drag Y1 - 1997 SN - 3-528-06960-0 U6 - https://doi.org/10.1007/978-3-322-86573-1_2 SP - 7 EP - 14 PB - Vieweg CY - Braunschweig [u.a.] ER - TY - JOUR A1 - Mertens, Josef T1 - Luft hat keine Balken, aber enorme Kräfte : Aerodynamik - die unsichtbare Kraft JF - HEmagazin : das Hocheffizienz-Magazin von Wilo. 2006 (2006), H. 1 Y1 - 2006 SP - 4 EP - 9 PB - - ER - TY - JOUR A1 - Mertens, Josef T1 - Required technologies for supersonic aircraft JF - Fluid dynamics research on supersonic aircraft : this report is a compilation of the edited proceedings of the special course on "Fluid dynamic research on supersonic aircraft" held at the Karman Institute for Fluid Dynamics (VKI) in Rhode-Saint-Genese, Belgium, 25-29 May 1998 Y1 - 1998 SN - 92-837-1007-X N1 - (RTO educational notes ; 4) SP - 5.1 EP - 5.16 PB - Research and Technology Organization CY - Neuilly-sur-Seine ER - TY - JOUR A1 - Mertens, Josef T1 - Multi point design challenges for supersonic transports JF - Fluid dynamics research on supersonic aircraft : this report is a compilation of the edited proceedings of the special course on "Fluid dynamics research on supersonic aircraft" held at the Karman Institute for Fluid Dynamics (VKI) in Rhode-Saint-Genese, Belgium, 25-29 May 1998 Y1 - 1998 SN - 92-837-1007-X SP - 8.1 EP - 8.12 PB - Research and Technology Organization CY - Neuilly-sur-Seine ER - TY - JOUR A1 - Mertens, Josef T1 - Aerodynamische Ziele des Adaptiven Flügels (ADIF). JF - DGLR-Jahrbuch 1998 Bd. 1 Y1 - 1998 N1 - DGLR-JT98-213 SP - 47 EP - 52 ER - TY - JOUR A1 - Mertens, Josef T1 - Einige herausragende Ergebnisse des Technologieprogramms "Reduktion des Aerodynamischen Widerstands (RaWid)" JF - DGLR-Jahrbuch 1999 Bd. 3 Y1 - 1999 N1 - DGLR-JT99-047 SP - 1461 EP - 1468 ER - TY - BOOK A1 - Mertens, Josef T1 - Reduktion des aerodynamischen Widerstands (RaWid) : Abschlußbericht ; Laufzeit des Vorhaben, Berichtszeitraum: 01.07.1995 bis 31.12.1998 / Verf.: J. Mertens Y1 - 1999 N1 - Förderkenzeichen BMBF 20 A 9595 A. Engl. Zsfassung u.d.T.: Reduction of aerodynamis drag (RaWid) - final report . auch als elektronisches Dokument vorh. PB - DaimlerChrysler Aerospare Airbus GmbH CY - Hamburg ER - TY - BOOK A1 - Mertens, Josef T1 - Reduktion des aerodynamischen Widerstands (RaWid) : Abschlußbericht ; Laufzeit des Vorhaben, Berichtszeitraum: 01.07.1995 bis 31.12.1998 / Verf.: J. Mertens Y1 - 1999 N1 - Parallel als gedruckte Ausgabe erschienen PB - DaimlerChrysler Aerospare Airbus GmbH CY - Hamburg ER - TY - JOUR A1 - Mertens, Josef T1 - Laminar flow for supersonic transports JF - Proceedings : March 16 - 18, 1992, Congress Centrum, Hamburg, Federal Republic of Germany / organized jointly by: Deutsche Gesellschaft für Luft- und Raumfahrt e.V. ... [Programme committee J. Szodruch ...] Y1 - 1992 SN - 3-922010-73-3 N1 - DGLR-Bericht ; 92,06 SP - 319 EP - 323 PB - DGLR CY - Bonn ER - TY - CHAP A1 - Mertens, Josef ED - Nitsche, Wolfgang T1 - Some important results of the technology programme RaWid T2 - New Results in Numerical and Experimental Fluid Mechanics : Contributions to the 11th AG STAB/DGLR Symposium Berlin, Germany 1998. - Vol. 2. - (Notes on Numerical Fluid Mechanics ; 72) Y1 - 1999 SN - 978-3-663-10903-7 (Print) SN - 978-3-663-10901-3 (Elektronisch) U6 - https://doi.org/10.1007/978-3-663-10901-3_41 SP - 315 EP - 322 PB - Springer Fachmedien CY - Wiesbaden ER - TY - CHAP A1 - Mertens, Josef A1 - Becker, K. ED - Ballmann, Josef T1 - Numerical solution of flow equations : an aircraft designer's view T2 - Nonlinear hyperbolic equations - theory, computation methods, and applications : proceedings of the 2nd International Conference on Nonlinear Hyperbolic Problems, Aachen, FRG, March 14 to 18, 1988. - (Notes on Numerical Fluid Mechanics ; 24) N2 - Today the most accurate and cost effective industrial codes used in aircraft design are based on the full potential equation coupled with boundary layer equations. However, these are not capable to solve complicated three-dimensional problems of vortical flows and shocks. On the other hand Euler and Navier-Stokes codes are too expensive and not accurate enough for design purposes, especially in regard of drag and interference prediction. The reasons for these deficiencies are investigated and a way to overcome them by future developments is demonstrated. Y1 - 1989 SN - 3-528-08098-1 U6 - https://doi.org/10.1007/978-3-322-87869-4_41 N1 - International Conference on Nonlinear Hyperbolic Problems <3, 1988, Aachen> SP - 403 EP - 412 PB - Vieweg CY - Braunschweig ER - TY - JOUR A1 - Mertens, Josef A1 - Henke, Rolf T1 - Adaptive technologies for future civil air transport JF - Air & Space Europe. 3 (2001), H. 3-4 Y1 - 2001 SN - 1247-5793 SP - 80 EP - 82 ER - TY - JOUR A1 - Mertens, Josef A1 - Hünecke, Klaus T1 - Experimentelle Untersuchung zur Landeeigenschaft von Hyperschall-Fluggeräten / Hünecke, Klaus ; Mertens, Josef JF - DGLR-Jahrbuch 1988 Bd. 1 Y1 - 1988 N1 - DGLR-88-123 SP - 706 ER - TY - JOUR A1 - Mertens, Josef A1 - Kelm, R. A1 - Velden, A. van der T1 - Interdisziplinäre Auslegung eines Verkehrsflugzeugflügels JF - DGLR-Jahrbuch 1999 Bd. 3 Y1 - 1999 N1 - DGLR-JT99-156 SP - 1605 EP - 1610 ER - TY - JOUR A1 - Mertens, Josef A1 - Klevenhusen, K. D. A1 - Jakob, H. T1 - Accurate Transonic Wave Drag Prediction Using Simple Physical Models JF - AIAA-Journal. 25 (1987), H. 6 Y1 - 1987 SN - 0001-1452 SP - 799 EP - 805 ER - TY - PAT A1 - Mertens, Josef A1 - Lajain, Henri T1 - Method of fabricating leading edge nose structures of aerodynamic surfaces : patent no.: US 6,415,510 B2 ; date of patent: Jul. 9, 2002 Y1 - 2002 N1 - Volltext auch in der Datenbank http://publikationen.dpma.de/ zu finden unter der Nummer US000006415510B2 PB - United States Patent and Trademark Office CY - [Washington, DC] ER - TY - JOUR A1 - Mertens, Josef A1 - Röger, Wolf T1 - F-Schlepp: Problem Taumelschwingung JF - Aerokurier. 44 (2000), H. 10 Y1 - 2000 SN - 0341-1281 N1 - in der Bereichsbibliothek unter der Signatur 23 Z 391-2000 SP - 73 EP - 73 ER - TY - PAT A1 - Mertens, Josef A1 - Velden, Alexander van der A1 - Kelm, Roland T1 - Flugzeug mit Flügeln, deren maximaler Auftrieb durch steuerbare Flügelkomponenten veränderbar ist : Offenlegungsschrift DE102004045732 ; Offenlegungstag: 30.03.2006 = Aircraft with wings whose maximum lift can be altered by controllable wing components Y1 - 2006 N1 - Zugleich EP1791755A1. - Volltext über Datenbank: http://publikationen.dpma.de/ PB - Deutsches Patent- und Markenamt CY - München ER - TY - BOOK A1 - Mertens, Josef A1 - Velden, Alexander van der A1 - Kelm, Roland A1 - Kokan, David T1 - Application of MDO to large subsonic transport aircraft Y1 - 2000 N1 - Aerospace Sciences Meeting and Exhibit <38, 2000, Reno, NV> ; (AIAA Paper ; 00-0844) PB - American Institute of Aeronautics and Astronautics CY - Reston, Va. ER - TY - JOUR A1 - Meyer, Max-Arno A1 - Granrath, Christian A1 - Feyerl, Günter A1 - Richenhagen, Johannes A1 - Kaths, Jakob A1 - Andert, Jakob T1 - Closed-loop platoon simulation with cooperative intelligent transportation systems based on vehicle-to-X communication JF - Simulation Modelling Practice and Theory Y1 - 2021 U6 - https://doi.org/10.1016/j.simpat.2020.102173 SN - 1569-190X VL - 106 IS - Art. 102173 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Mulsow, Niklas A. A1 - Hülsen, Benjamin A1 - Gützlaff, Joel A1 - Spies, Leon A1 - Bresser, Andreas A1 - Dabrowski, Adam A1 - Czupalla, Markus A1 - Kirchner, Frank T1 - Concept and design of an autonomous micro rover for long term lunar exploration T2 - Proceedings of the 74th International Astronautical Congress N2 - Research on robotic lunar exploration has seen a broad revival, especially since the Google Lunar X-Prize increasingly brought private endeavors into play. This development is supported by national agencies with the aim of enabling long-term lunar infrastructure for in-situ operations and the establishment of a moon village. One challenge for effective exploration missions is developing a compact and lightweight robotic rover to reduce launch costs and open the possibility for secondary payload options. Existing micro rovers for exploration missions are clearly limited by their design for one day of sunlight and their low level of autonomy. For expanding the potential mission applications and range of use, an extension of lifetime could be reached by surviving the lunar night and providing a higher level of autonomy. To address this objective, the paper presents a system design concept for a lightweight micro rover with long-term mission duration capabilities, derived from a multi-day lunar mission scenario at equatorial regions. Technical solution approaches are described, analyzed, and evaluated, with emphasis put on the harmonization of hardware selection due to a strictly limited budget in dimensions and power. Y1 - 2023 N1 - 74. International Astronautical Congress (IAC-2023), October 2-6 2023, Baku, Azerbaijan PB - dfki CY - Saarbrücken ER - TY - JOUR A1 - Möhren, Felix A1 - Bergmann, Ole A1 - Janser, Frank A1 - Braun, Carsten T1 - Assessment of structural mechanical effects related to torsional deformations of propellers JF - CEAS Aeronautical Journal N2 - Lifting propellers are of increasing interest for Advanced Air Mobility. All propellers and rotors are initially twisted beams, showing significant extension–twist coupling and centrifugal twisting. Torsional deformations severely impact aerodynamic performance. This paper presents a novel approach to assess different reasons for torsional deformations. A reduced-order model runs large parameter sweeps with algebraic formulations and numerical solution procedures. Generic beams represent three different propeller types for General Aviation, Commercial Aviation, and Advanced Air Mobility. Simulations include solid and hollow cross-sections made of aluminum, steel, and carbon fiber-reinforced polymer. The investigation shows that centrifugal twisting moments depend on both the elastic and initial twist. The determination of the centrifugal twisting moment solely based on the initial twist suffers from errors exceeding 5% in some cases. The nonlinear parts of the torsional rigidity do not significantly impact the overall torsional rigidity for the investigated propeller types. The extension–twist coupling related to the initial and elastic twist in combination with tension forces significantly impacts the net cross-sectional torsional loads. While the increase in torsional stiffness due to initial twist contributes to the overall stiffness for General and Commercial Aviation propellers, its contribution to the lift propeller’s stiffness is limited. The paper closes with the presentation of approximations for each effect identified as significant. Numerical evaluations are necessary to determine each effect for inhomogeneous cross-sections made of anisotropic material. KW - Lifting propeller KW - Extension–twist coupling KW - Trapeze effect KW - Centrifugal twisting moment Y1 - 2024 U6 - https://doi.org/10.1007/s13272-024-00737-7 SN - 1869-5590 (eISSN) SN - 1869-5582 N1 - Corresponding author: Felix Möhren PB - Springer CY - Wien ER - TY - JOUR A1 - Möhren, Felix A1 - Bergmann, Ole A1 - Janser, Frank A1 - Braun, Carsten T1 - On the influence of elasticity on propeller performance: a parametric study JF - CEAS Aeronautical Journal N2 - The aerodynamic performance of propellers strongly depends on their geometry and, consequently, on aeroelastic deformations. Knowledge of the extent of the impact is crucial for overall aircraft performance. An integrated simulation environment for steady aeroelastic propeller simulations is presented. The simulation environment is applied to determine the impact of elastic deformations on the aerodynamic propeller performance. The aerodynamic module includes a blade element momentum approach to calculate aerodynamic loads. The structural module is based on finite beam elements, according to Timoshenko theory, including moderate deflections. Several fixed-pitch propellers with thin-walled cross sections made of both isotropic and non-isotropic materials are investigated. The essential parameters are varied: diameter, disc loading, sweep, material, rotational, and flight velocity. The relative change of thrust between rigid and elastic blades quantifies the impact of propeller elasticity. Swept propellers of large diameters or low disc loadings can decrease the thrust significantly. High flight velocities and low material stiffness amplify this tendency. Performance calculations without consideration of propeller elasticity can lead to decreased efficiency. To avoid cost- and time-intense redesigns, propeller elasticity should be considered for swept planforms and low disc loadings. KW - Propeller KW - Finite element method KW - Blade element method KW - Propeller elasticity KW - Aeroelasticity Y1 - 2023 U6 - https://doi.org/10.1007/s13272-023-00649-y SN - 1869-5590 (Online) SN - 1869-5582 (Print) N1 - Corresponding author: Felix Möhren VL - 14 SP - 311 EP - 323 PB - Springer Nature CY - Berlin ER - TY - CHAP A1 - Möhren, Felix A1 - Bergmann, Ole A1 - Janser, Frank A1 - Braun, Carsten T1 - On the determination of harmonic propeller loads T2 - AIAA SCITECH 2023 Forum N2 - Dynamic loads significantly impact the structural design of propeller blades due to fatigue and static strength. Since propellers are elastic structures, deformations and aerodynamic loads are coupled. In the past, propeller manufacturers established procedures to determine unsteady aerodynamic loads and the structural response with analytical steady-state calculations. According to the approach, aeroelastic coupling primarily consists of torsional deformations. They neglect bending deformations, deformation velocities, and inertia terms. This paper validates the assumptions above for a General Aviation propeller and a lift propeller for urban air mobility or large cargo drones. Fully coupled reduced-order simulations determine the dynamic loads in the time domain. A quasi-steady blade element momentum approach transfers loads to one-dimensional finite beam elements. The simulation results are in relatively good agreement with the analytical method for the General Aviation propeller but show increasing errors for the slender lift propeller. The analytical approach is modified to consider the induced velocities. Still, inertia and velocity proportional terms play a significant role for the lift propeller due to increased elasticity. The assumption that only torsional deformations significantly impact the dynamic loads of propellers is not valid. Adequate determination of dynamic loads of such designs requires coupled aeroelastic simulations or advanced analytical procedures. Y1 - 2023 U6 - https://doi.org/10.2514/6.2023-2404 N1 - AIAA SCITECH 2023 Forum, 23-27 January 2023, National Harbor, Md & Online PB - AIAA ER - TY - JOUR A1 - Neu, Eugen A1 - Janser, Frank A1 - Khatibi, Akbar A. A1 - Braun, Carsten A1 - Orifici, Adrian C. T1 - Operational Modal Analysis of a wing excited by transonic flow JF - Aerospace Science and Technology N2 - Operational Modal Analysis (OMA) is a promising candidate for flutter testing and Structural Health Monitoring (SHM) of aircraft wings that are passively excited by wind loads. However, no studies have been published where OMA is tested in transonic flows, which is the dominant condition for large civil aircraft and is characterized by complex and unique aerodynamic phenomena. We use data from the HIRENASD large-scale wind tunnel experiment to automatically extract modal parameters from an ambiently excited wing operated in the transonic regime using two OMA methods: Stochastic Subspace Identification (SSI) and Frequency Domain Decomposition (FDD). The system response is evaluated based on accelerometer measurements. The excitation is investigated from surface pressure measurements. The forcing function is shown to be non-white, non-stationary and contaminated by narrow-banded transonic disturbances. All these properties violate fundamental OMA assumptions about the forcing function. Despite this, all physical modes in the investigated frequency range were successfully identified, and in addition transonic pressure waves were identified as physical modes as well. The SSI method showed superior identification capabilities for the investigated case. The investigation shows that complex transonic flows can interfere with OMA. This can make existing approaches for modal tracking unsuitable for their application to aircraft wings operated in the transonic flight regime. Approaches to separate the true physical modes from the transonic disturbances are discussed. Y1 - 2016 U6 - https://doi.org/10.1016/j.ast.2015.11.032 SN - 1270-9638 VL - 49 SP - 73 EP - 79 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Neu, Eugen A1 - Janser, Frank A1 - Khatibi, Akbar A. A1 - Orifici, Adrian C. T1 - Operational modal analysis of a cantilever in a wind tunnel using optical fiber bragg grating sensors T2 - 6th International Operational Modal Analysis Conference. IOMAC´15. 2015 May 12-14 Gijon - Spain Y1 - 2015 U6 - https://doi.org/10.13140/RG.2.1.3753.0324 ER - TY - CHAP A1 - Neu, Eugen A1 - Janser, Frank A1 - Khatibi, Akbar A. A1 - Orifici, Adrian C. T1 - In-flight vibration-based structural health monitoring of aircraft wings T2 - 30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea N2 - This work presents a methodology for automated damage-sensitive feature extraction and anomaly detection under multivariate operational variability for in-flight assessment of wings. The method uses a passive excitation approach, i. e. without the need for artificial actuation. The modal system properties (natural frequencies and damping ratios) are used as damage-sensitive features. Special emphasis is placed on the use of Fiber Bragg Grating (FBG) sensing technology and the consideration of Operational and Environmental Variability (OEV). Measurements from a wind tunnel investigation with a composite cantilever equipped with FBG and piezoelectric sensors are used to successfully detect an impact damage. In addition, the feasibility of damage localisation and severity estimation is evaluated based on the coupling found between damageand OEV-induced feature changes. Y1 - 2016 ER - TY - JOUR A1 - Neu, Eugen A1 - Janser, Frank A1 - Khatibi, Akbar A. A1 - Orifici, Adrian C. T1 - Fully Automated Operational Modal Analysis using multi-stage clustering JF - Mechanical Systems and Signal Processing Y1 - 2017 U6 - https://doi.org/10.1016/j.ymssp.2016.07.031 SN - 0888-3270 VL - Vol. 84, Part A SP - 308 EP - 323 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Neu, Eugen A1 - Janser, Frank A1 - Khatibi, Akbar A. A1 - Orifici, Adrian C. T1 - Automated modal parameter-based anomaly detection under varying wind excitation JF - Structural Health Monitoring N2 - Wind-induced operational variability is one of the major challenges for structural health monitoring of slender engineering structures like aircraft wings or wind turbine blades. Damage sensitive features often show an even bigger sensitivity to operational variability. In this study a composite cantilever was subjected to multiple mass configurations, velocities and angles of attack in a controlled wind tunnel environment. A small-scale impact damage was introduced to the specimen and the structural response measurements were repeated. The proposed damage detection methodology is based on automated operational modal analysis. A novel baseline preparation procedure is described that reduces the amount of user interaction to the provision of a single consistency threshold. The procedure starts with an indeterminate number of operational modal analysis identifications from a large number of datasets and returns a complete baseline matrix of natural frequencies and damping ratios that is suitable for subsequent anomaly detection. Mahalanobis distance-based anomaly detection is then applied to successfully detect the damage under varying severities of operational variability and with various degrees of knowledge about the present operational conditions. The damage detection capabilities of the proposed methodology were found to be excellent under varying velocities and angles of attack. Damage detection was less successful under joint mass and wind variability but could be significantly improved through the provision of the currently encountered operational conditions. Y1 - 2016 U6 - https://doi.org/10.1177/1475921716665803 SN - 1475-9217 VL - 15 IS - 6 SP - 1 EP - 20 PB - Sage CY - London ER - TY - CHAP A1 - Niedermeier, H. A1 - Clemens, J. A1 - Kowalski, Julia A1 - Macht, S. A1 - Heinen, D. A1 - Hoffmann, R. A1 - Linder, Peter T1 - Navigation system for a research ice probe for antarctic glaciers T2 - IEEE/ION Position, Location and Navigation Symposium (PLANS) ; 5-8 May 2014, Monterey, Calif. Y1 - 2014 SN - 978-1-4799-3319-8 SP - 959 EP - 975 PB - IEEE CY - Piscataway, NJ ER - TY - PAT A1 - Nonhoff, Gottfried A1 - Wahle, Michael T1 - Anordnung zur Dämpfung von Schwingungen an Bauwerken und Bauteilen : Offenlegungsschrift / Europäische Patentschrift T1 - Arrangement for damping vibrations of structures or parts thereof : patent of invention Y1 - 1990 PB - Deutsches Patent- und Markenamt / Europäisches Patentamt CY - München / Den Hague ER - TY - CHAP A1 - Nowack, N. A1 - Röth, Thilo A1 - Bührig-Polaczek, A. A1 - Klaus, G. ED - Hirsch, Jürgen T1 - Advanced Sheet Metal Components Reinforced by Light Metal Cast Structures T2 - Aluminium alloys : their physical and mechanical properties ; [proceedings of the 11th International Conference on Aluminium Alloys, 22 - 26 Sept. 2008, Aachen, Germany ; ICAA 11] Y1 - 2008 SN - 978-3-527-32367-8 IS - 2 SP - 2374 EP - 2381 ER - TY - CHAP A1 - Ohndorf, Andreas A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Schartner, Karl-Heinz T1 - Flight times to the heliopause using a combination of solar and radioisotope electric propulsion T2 - 32nd International Electric Propulsion Conference N2 - We investigate the interplanetary flight of a low-thrust space probe to the heliopause,located at a distance of about 200 AU from the Sun. Our goal was to reach this distance within the 25 years postulated by ESA for such a mission (which is less ambitious than the 15-year goal set by NASA). Contrary to solar sail concepts and combinations of allistic and electrically propelled flight legs, we have investigated whether the set flight time limit could also be kept with a combination of solar-electric propulsion and a second, RTG-powered upper stage. The used ion engine type was the RIT-22 for the first stage and the RIT-10 for the second stage. Trajectory optimization was carried out with the low-thrust optimization program InTrance, which implements the method of Evolutionary Neurocontrol,using Artificial Neural Networks for spacecraft steering and Evolutionary Algorithms to optimize the Neural Networks’ parameter set. Based on a parameter space study, in which the number of thrust units, the unit’s specific impulse, and the relative size of the solar power generator were varied, we have chosen one configuration as reference. The transfer time of this reference configuration was 29.6 years and the fastest one, which is technically more challenging, still required 28.3 years. As all flight times of this parameter study were longer than 25 years, we further shortened the transfer time by applying a launcher-provided hyperbolic excess energy up to 49 km2/s2. The resulting minimal flight time for the reference configuration was then 27.8 years. The following, more precise optimization to a launch with the European Ariane 5 ECA rocket reduced the transfer time to 27.5 years. This is the fastest mission design of our study that is flexible enough to allow a launch every year. The inclusion of a fly-by at Jupiter finally resulted in a flight time of 23.8 years,which is below the set transfer-time limit. However, compared to the 27.5-year transfer,this mission design has a significantly reduced launch window and mission flexibility if the escape direction is restricted to the heliosphere’s “nose". KW - low-thrust trajectory optimization KW - heliosphere KW - ion propulsion Y1 - 2011 N1 - IEPC-2011-051 32nd International Electric Propulsion Conference,September 11–15, 2011 Wiesbaden, Germany SP - 1 EP - 12 ER - TY - JOUR A1 - Olaru, Alexandra Maria A1 - Kowalski, Julia A1 - Sethi, Vaishali A1 - Blümich, Bernhard T1 - Exchange relaxometry of flow at small Péclet numbers in a glass bead pack JF - Journal of Magnetic Resonance (JMR) N2 - In this paper we consider low Péclet number flow in bead packs. A series of relaxation exchange experiments has been conducted and evaluated by ILT analysis. In the resulting correlation maps, we observed a collapse of the signal and a translation towards smaller relaxation times with increasing flow rates, as well as a signal tilt with respect to the diagonal. In the discussion of the phenomena we present a mathematical theory for relaxation exchange experiments that considers both diffusive and advective transport. We perform simulations based on this theory and discuss them with respect to the conducted experiments. KW - NMR exchange relaxometry KW - Low-field NMR Y1 - 2012 U6 - https://doi.org/10.1016/j.jmr.2012.04.015 SN - 1096-0856 VL - 220 SP - 32 EP - 44 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Olaru, Alexandra Maria A1 - Kowalski, Julia A1 - Sethi, Vaishali A1 - Blümich, Bernhard T1 - Fluid Transport in Porous Media probed by Relaxation-Exchange NMR T2 - 2011 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec. Y1 - 2011 N1 - H12B-07; American Geophysical Union ER - TY - CHAP A1 - Otten, D. A1 - Schmid, M. A1 - Weber, Tobias T1 - Advances In Sheet Metal-Forming: Reduction Of Tooling Cost By Methodical Optimization T2 - Proceedings of SAMPE Europe Conference, Amiens , France Y1 - 2015 ER - TY - CHAP A1 - Otten, D. A1 - Schmidt, M. A1 - Weber, Tobias T1 - Advances in Determination of Material Parameters for Functional Simulations Based on Process Simulations T2 - SAMPE Europe Conference 16 Liege Y1 - 2016 SN - 978-1-5108-3800-0 SP - 570 EP - 577 ER - TY - JOUR A1 - Otten, Dennis A1 - Weber, Tobias A1 - Arent, Jan-Christoph T1 - Manufacturing Process Simulation – On Its Way to Industrial Application JF - International Journal of Aviation, Aeronautics, and Aerospace N2 - Manufacturing process simulation (MPS) has become more and more important for aviation and the automobile industry. A highly competitive market requires the use of high performance metals and composite materials in combination with reduced manufacturing cost and time as well as a minimization of the time to market for a new product. However, the use of such materials is expensive and requires sophisticated manufacturing processes. An experience based process and tooling design followed by a lengthy trial-and-error optimization is just not contemporary anymore. Instead, a tooling design process aided by simulation is used more often. This paper provides an overview of the capabilities of MPS in the fields of sheet metal forming and prepreg autoclave manufacturing of composite parts summarizing the resulting benefits for tooling design and manufacturing engineering. The simulation technology is explained briefly in order to show several simplification and optimization techniques for developing industrialized simulation approaches. Small case studies provide examples of an efficient application on an industrial scale. Y1 - 2018 U6 - https://doi.org/10.15394/ijaaa.2018.1217 SN - 2374-6793 VL - 5 IS - 2 PB - Embry-Riddle Aeronautical University CY - Daytona Beach, Fla. ER - TY - JOUR A1 - Overduin, James A1 - Blome, Hans-Joachim A1 - Hoell, Josef T1 - Wolfgang Priester: from the big bounce to the Lambda-dominated universe JF - Naturwissenschaften Y1 - 2007 SN - 0028-1042 VL - 94 IS - 6 SP - 417 EP - 429 ER - TY - CHAP A1 - Pasligh, N. A1 - Funke, D. A1 - Röth, Thilo A1 - Krack, R. T1 - Leichtbau Quertrager als Stahlblech-Aluminiumdruckguss-Hybrid - Von der numerischen Berechnung bis zum realen Prototypen T2 - VDI BERICHTE Y1 - 2010 SN - 978-3-18-092107-5 N1 - 15. Kongress SIMVEC Berechnung und Simulation im Fahrzeugbau, Baden-Baden, 16. und 17. November 2010 PB - VDI Verlag CY - Düsseldorf ER - TY - JOUR A1 - Peeken, Heinz A1 - Rosenkranz, Josef A1 - Schelenz, R. T1 - Berücksichtigung des Einflusses der Gleitlagergehäusesteifigkeit auf das dynamische Verhalten von Rotoren JF - Antriebstechnik : Organ der Forschungsvereinigung Antriebstechnik e.V. Y1 - 1991 SN - 0341-2652 VL - 30 IS - 9 SP - 71 EP - 75 ER - TY - CHAP A1 - Peeken, Heinz A1 - Troeder, Christoph A1 - Schmidt, J. A1 - Rosenkranz, Josef T1 - Principles of machine noise reduction T2 - Inter-noise 85 : proceedings ; 1985 international conference on noise control engineering ; Munich, Sept. 18 - 20, 1985. - (Schriftenreihe der Bundesanstalt für Arbeitsschutz : Tagungsbericht ; 39) Y1 - 1985 SN - 3-88314-417-7 SP - 23 EP - 36 PB - Bundesanstalt für Arbeitsschutz [u.a.] CY - Dortmund [u.a.] ER - TY - CHAP A1 - Peloni, A. A1 - Ceriotti, M. A1 - Dachwald, Bernd T1 - Preliminary trajectory design of a multiple NEO rendezvous mission through solar sailing T2 - Proceedings of the International Astronautical Congress, IAC, Vol. 8, 2014 Y1 - 2015 SN - 978-1-63439-986-9 SP - 5352 EP - 5366 PB - Curran CY - Red Hook, NY ER -