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36th AIAA Applied Aerodynamics Conference, 2018

作者： Hasan, Yasim J. Flink, Jan Freund, Sebastian Klimmek, Thomas Kuchar, Richard Liersch, Carsten M. Looye, Gertjan Moerland, Erwin Pfeiffer, Till Schrader, Mario Zenkner, Sebastian Institute of Flight Systems Braunschweig38108 Germany Simulation and Software Technology Köln51147 Germany Institute of Composite Structures and Adaptive Systems Braunschweig38108 Germany Institute of Aeroelasticity Göttingen37073 Germany Institute of System Dynamics and Control Wessling82234 Germany Institute of Aerodynamics and Flow Technology Braunschweig38108 Germany Wessling82234 Germany Institute of System Architectures in Aeronautics Hamburg21129 Germany Institute of Propulsion Technology Köln51147 Germany

ISBN: (数字)9781624105593

ISBN: (纸本)9781624105593

This paper provides an overview of current activities of DLR (German Aerospace Center) with respect to stability and control investigations in the context of early stages of aircraft design. For this purpose, DLR follows an interdisciplinary and multi-level design approach. Using an integration framework in combination with a central data exchange format, largely automated process chains are set up that combine calculation and simulation capabilities of the multitude of disciplines required in early aircraft design. Rather than using empirical relations and assumptions based on experience, the underlying methods applied by the tools are mainly based on physical model representations. The major aim of this design approach is to generate all relevant data needed for stability and control investigations, including aerodynamic damping derivatives and to assemble them within a flight dynamics model. Not only does this approach allow for an early consideration of stability and control characteristics, but it also respects interdisciplinary effects and enables automated design changes. This paper describes the infrastructure used for setting up the described process. It presents disciplinary tools used to calculate engine performance maps, calculate aerodynamic performance maps and structural properties, generate flight dynamics models with associated control laws and to assess aircraft handling qualities. Furthermore, this paper provides application examples of early stability and control considerations, using integrated interdisciplinary process chains. This comprises a handling qualities assessment under uncertainty considerations and vertical tailplane sizing for a blended wing body. In addition, engine and split flap sizing processes for an unmanned combat aerial vehicle are shown. The interdisciplinary design approach presented here, serves to find a well justified early configuration and reduces the risk of later design changes. © 2018, American Institute of Aeronau

关键词： Engines

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Multi-level MDO of a long-range transport aircraft using a distributed analysis framework 18

Multi-level MDO of a long-range transport aircraft using a d...

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18th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, 2017

作者： Görtz, Stefan Ilic, Caslav Schuster, Andreas Jepsen, Jonas Leitner, Martin Schulze, Matthias Scherer, Julian Petsch, Michael Becker, Richard Zur, Sascha Institute of Aerodynamics and Flow Technology C2A2S2E Lilienthalplatz 7 Braunschweig38108 Germany Institute of Aerodynamics and Flow Technology Lilienthalplatz 7 Braunschweig38108 Germany Institute of Composite Structures and Adaptive Systems Lilienthalplatz 7 Braunschweig38108 Germany Institute of Air Transportation Systems Blohmstr. 20 Hamburg21079 Germany Institute of System Dynamics and Control Münchner Str. 20 Oberpfaffenhofen82234 Germany Institute of Aeroelasticity Bunsenstr. 10 Göttingen37073 Germany Institute of Structures and Design Pfaffenwaldring 38 Stuttgart70569 Germany Institute of Propulsion Technology Linder Höhe Köln51147 Germany Simulation and Software Technology Linder Höhe Köln51147 Germany

ISBN: (数字)9781624105074

ISBN: (纸本)9781624105074

DLR’s work on developing a distributed collaborative MDO environment is presented. A multi-level approach combining high-fidelity MDA for aerodynamics and structures with conceptual aircraft design methods is employed. Configuration-specific sizing loads are evaluated and used for sizing the structure. A gradient-free optimization algorithm is used to optimize the fuel burn of a generic long-range wide-body transport aircraft configuration with 9 shape parameters. The results show a truly multidisciplinary improvement of the modified design. The result of a gradient-free high-fidelity MDO with preselected load cases and five shape parameters is also presented, comparing a full mission analysis with results for the Breguet range equation. © 2017 American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Aerodynamics

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Modeling and experimental analysis of a 6-high industrial rolling mill vibration response

Modeling and experimental analysis of a 6-high industrial ro...

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7th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2010, CM 2010/MFPT 2010

作者： Gryllias, Konstantinos C. Antoniadis, Ioannis A. National Technical University of Athens School of Mechanical Engineering Machine Design and Control Systems Section Dynamics and Structures Laboratory Athens 15773 Greece

ISBN: (纸本)9781618390134

During cold rolling of thin sheet, the operation is often accompanied by a variety of undesirable mechanical vibrations, generally referred to as chatter. Chatter is often associated with high rolling speeds and high thickness reductions, conditions that are generally desirable in order to increase mill productivity. Chatter can lead to unacceptable gauge fluctuations, sheet corrugations, surface imperfections, damage to mills and undesirable noise in the work environment. Four and six degree of freedom (DOF) systems describing chatter in sheet rolling in a 6-High rolling mill are proposed. The natural frequencies and the modes of the systems are extracted. The investigation includes the additional plastic deformation of the sheet in the roll-bite that is present during chatter as well as the force displacement relation between the cylindrical rolls being pressed together which is inherently nonlinear due to the changing contact area. It appears that the models are capable of predicting third octave chatter, in addition to fifth octave chatter. A number of mill operational parameters are considered. The models are validated using measurements performed at an industrial 6-high aluminium rolling mill.

关键词： Cold rolling

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A Device that can Produce Net Impulse Using Rotating Masses

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Engineering（科研） 2010年第8期2卷 648-657页

作者： Christopher G. Provatidis Laboratory of Dynamics & Structures Mechanical Design & Control Systems Section School of Mechanical Engineering National Technical University of Athens

This paper describes a device capable of producing net impulse, through two synchronized masses, which move along a figure-eight-shaped orbit. In addition to the detailed description of the mechanical components of this device, particular attention is paid to the theoretical treatment of the innovative principle on which the device is based. In more details, the mechanical system consists of two independent but simultaneous rotations, the former being related to the formation of the figure-eight-shaped path and the latter to an additional spinning. Based on the parametric equations of motion of the lumped masses, and considering semi-static tensile deformation of the connecting rods carrying them, it was found that the resultant impulse towards the direction of the spin vector includes a non-vanishing term that is linearly proportional to the time. In addition, reduced but encouraging experimental results are reported. These findings sustain the capability of the proposed mechanism to achieve propulsion.

关键词： Inertial Propulsion Centrifugal Force Net Impulse Rotating Figure-Eight Mechanism

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Automated diagnostic approaches for defective rolling element bearings using minimal training pattern classification methods

Automated diagnostic approaches for defective rolling elemen...

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4th World Congress on Engineering Asset Management: Engineering Asset Lifecycle Management, WCEAM 2009

作者： Gryllias, K.C. Yiakopoulos, C. Antoniadis, I. School of Mechanical Engineering Machine Design and Control Systems Section Dynamics and Structures Laboratory Athens 15773 Greece

ISBN: (纸本)9781849960021

Rolling Element Bearings consist one of the most widely used industrial machine elements, being the interface between the stationary and the rotating part of the machine. Due to their importance a plethora of monitoring methods and fault diagnosis procedures have been developed, in order to reduce maintenance costs, improve productivity, and prevent malfunctions and failures during operation which could lead to the downtime of the machine. Towards this direction, among different automatic diagnostic methods, the Support Vector Machine (SVM) method has been shown to present a number of advantages. Support Vector Machine is a relatively new computational learning method based on Statistical Learning Theory and combines fundamental concepts and principles related to learning, well-defined formulation and self-consistent mathematical theory. The key aspects about the use of SVMs as a rolling element bearing health monitoring tool are the lack of actual experimental data, the optimal selection of the type and the number of input features, and the correct selection of the kernel function and its corresponding parameters. A large number of input features have been proposed, being divided in two big categories: A) Traditional signal statistical features in the time domain, such as mean value, rms value, variance, skewness, kurtosis etc, B) Frequency domain based indices, such as energy values obtained at characteristic frequency bands of the measured and the demodulated signals. In this paper, the structure and the performance of a Support Vector Machine based approach for rolling element bearing fault diagnosis is presented. The main advantage of this method is that the training of the SVM is based on a model describing the dynamic behavior of a defective rolling element bearing, enabling thus the direct application of the SVM to experimental measurements of defective bearings, without the need of training the SVM with experimental data of a defective bearing.

关键词： Support vector machines

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Doppler effect minimization in the spectra emitted by moving vehicles by the application of a Harmonic Signal Detection (HARD) Method

Doppler effect minimization in the spectra emitted by moving...

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6th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2009

作者： Yiakopoulos, C.T. Gryllias, K.C. Antoniadis, I.A. National Technical University of Athens School of Mechanical Engineering Machine Design and Control Systems Section Dynamics and Structures Laboratory Athens 15773 Greece

ISBN: (纸本)9781618390097

On-line fault diagnosis of moving vehicles is of increasing importance, especially if the diagnosis can be performed from a stationary byside station near the way of the moving vehicle. The diagnostically interesting information of a moving vehicle is available in the acoustic signal which is emitted by the source. However, the Doppler effect introduces a spectrum smear depending on the speed of the moving source, which shifts the interesting frequencies to different bands. A method is presented that allows the acquired information to be connected to the proper running of the moving vehicle, indicating the useful carrier frequencies of the source signals. The basic idea is based on the Harmonic Signal Detection Method. Since this method is a special parametric method performing directly in the time domain, it can track on-line the instantaneous speed of the moving object. The estimated speed variation of the moving object can be used to fix the problem of the frequency distortion introduced by the Doppler effect. The paper includes results of the proposed technique to simulated data and to an experimental measurement which was taken by a moving rail vehicle.

关键词： Doppler effect

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Demodulation of defective rolling element bearings vibration response with Complex Shifted Wavelets (CSMW) using a Peak Energy Criterion (PEC)

Demodulation of defective rolling element bearings vibration...

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6th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2009

ISBN: (纸本)9781618390097

Complex Shifted Morlet Wavelets (CSMW) can be used for the demodulation of the vibration response of defective rolling element bearings, as they present a number of advantages. The most important is that according to this method, the maximal timefrequency resolution is obtained, while the magnitudes of the complex wavelet coefficients in the time domain lead directly to the required envelope. However, the key element for the successful application of the method is the optimal selection and location of the corresponding necessary time-frequency window both in the time and in the frequency domains. For this reason, a Peak Energy Criterion (PEC) is proposed in order to tune the relevant wavelet window by choosing simultaneously in an optimal way and automatically both the center frequency and the bandwidth. A number of application cases are presented and the criterion demonstrates excellent behavior as it combines the benefits of energy based criteria, with criteria characterizing the spikiness of the response.

关键词： Demodulation

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Crack detection in structures, using proper orthogonal decomposition and morphological processing

Crack detection in structures, using proper orthogonal decom...

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13th International Congress on Sound and Vibration 2006, ICSV 2006

作者： Gryllias, K.C. Koukoulis, I.N. Yiakopoulos, C.T. Antoniadis, I.A. Provatidis, C.G. Dynamics and Structures Laboratory Machine Design and Control Systems Section National Technical University of Athens Athens 15773 Greece

ISBN: (纸本)9781627481502

Vibration analysis based damage identification in structures has been a subject of intensive research. As a result, a plethora of analytical, numerical and experimental techniques have been developed, involving frequency or mode-shape based methods, wavelet analysis, or higher order statistical signal processing. Parallel, a number of pattern recognition and classification approaches have been used, such as neural networks, either as standalone procedures, or in combination to the above techniques. In this paper, a method for crack dctcction in structures is presented. As a first step, using the Proper Orthogonal Decomposition (POD) method, a number of Proper Orthogonal Modes (POMs) of a crack cantilever beam are estimated. Proper Orthogonal Decomposition, closely related to Principal Component Analysis, is a powerful and elegant method of data analysis aimed at obtaining low-dimensional approximate descriptions of high-dimensional processes and eliminating noise effects. Then, the POMs are further processed, using basic morphological operators (dilation, erosion, opening, closing). The basic concept of morphological processing is to modify the shape of an object, equivalcntly considered as a set, by transforming it through its interaction with another object, called the structuring element. Using appropriate morphological processing, the position of the crack can be estimated by isolating the local sudden change effect of the crack on the space variation of each POM. Cantilever beams, containing a transverse surface opening-closing crack at different lengths and of different depths are considered and the influence of the type of the structuring element and of the noise level to the accuracy of the results is examined.© (2006) by the International Institute of Acoustics & Vibration.

关键词： Vibration analysis

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Announcements, comments, and acknowledgments

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AIAA Journal 2006年第1期44卷 1-10页

作者： Oran, Elaine Kailasanath, Kazhikathra Aggarwal, Suresh K. Ahmadian, Mehdi Alexandrov, Natalia Auweter-Kurtz, Monika Bailly, Christophe Balachandran, Balakumar Berman, Alex Candler, Graham V. Chelliah, Harsha K. Chokani, Ndaona Fujii, Kozo Gaitonde, Datta V. Ghia, Kirti Karman N. Givi, Peyman Gore, Jay P. Kaplan, Carolyn R. Livne, Eli Lucht, Robert P. Messac, Achille Wing, N.G. Palazotto, Anthony N. Pierre, Christophe Plotkin, Allen Roy, Ajit K. Saigal, Sunil Sforza, Pasquale M. Shivakumar, Kunigal N. So, Ronald M.C. Springer, Anthony M. Anatolitumin, Anthony M. Zhong, Xiaolin United States Division of Computational Physics United States United States AIAA United States APS United States National Academy of Engineering United States Center for Reactive Flow and Dynamical Systems Naval Research Laboratory United States Institute of Physics Department of Mechanical Engineering University of Illinois at Chicago United States ASME Combustion Institute Department of Mechanical Engineering Virginia Polytechnic Institute State University United States Aeronautics Systems Analysis Branch NASA Langley Research Center United States SIAM ISSMO Aerospace Engineering Institute of Space Systems Universität Stuttgart Germany Amelia Earhart Italy International Amelia Earhart Award Committee Italy France France Mechanical Engineering University of Maryland College Park United States AAM SPIE ASA ASME Technical Committees of Multi-Body Systems Nonlinear Dynamics Dynamics and Control of Structures and Systems American Helicopter Society United States Aerospace Engineering and Mechanics University of Minnesota United States AIAA Thermophysics Technical Committee Mechanical and Aerospace Engineering University of Virginia United States AIAA Propellants and Combustion Technical Committee AIAA's Transition Study Group Aerodynamics Measurement Technology Technical Committee Thermophysics Technical Committee Japan MOSAIC project on the Technology Pressure-sensitive Paint Measurement System Japan High-Speed Flows Group Air Vehicles Directorate Air Force Research Laboratory Wright-Patterson Air Force Base United States Wright State University United States Aerospace Engineering and Engineering Mechanics United States United States Mechanical Engineering University of Pittsburgh United States School of Mechanical Engineering Purdue University United States Committee on Heat Transfer in Fire and Combustion Systems Japan Board of Advisors Central States Section Combustion Institute United States AIChE United States Tau Beta Pi United States

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关键词： Institute of Space and Astronautical Science American Society of Mechanical Engineers Direct Numerical Simulation Aerospace Engineering MDO Propellant Air Forces Aerodynamics Heterogeneous Combustion NASA Langley Research Center

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Magnitude calibration of a fixed head star tracker using Astro-1 flight data

Magnitude calibration of a fixed head star tracker using Ast...

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AIAA Space Programs and Technologies Conference, 1992

作者： Rakoczy, John M. West, Mark E. Control Systems Division Structures and Dynamics Laboratory National Aeronautics and Space Administration Marshall Space Flight Center AL35812 United States

The Astro-1 ultraviolet astronomy mission was hampered by the failures of the automatic star acquisition procedure. The acquisition procedure depended on the Instrument Pointing Subsystem’s (IPS) Fixed Head Star Trackers (FHST) to acquire, track, and identify quidestars of known visual magnitude. During the Astro-1 mission it was suspected that the star magnitudes measured by the FHST were much lower than predicted. A post-flight investigation of the Astro-1 flight data confirmed and quantified this suspicion, Star magnitude calibration curves computed from the flight data depict the variance from the pre-flight calibration curves, These results are helping engineers to plan improvements to the acquisition procedure for the upcoming Astro-2 mission. © 1992 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Star trackers

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