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A Device that can Produce Net Impulse Using Rotating Masses

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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基于反常热传导的分数阶热弹耦合理论

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Acta Mechanica Sinica 2024年第5期40卷 141-149页

作者：尉亚军吴华邓子辰 School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi’an 710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi’an 710072 China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an 710049 China

原子模拟和实验研究表明低维纳米材料具有反常热传导特性,建立唯象反常热弹耦合模型,研究强热传导导致的热力耦合响应,对微纳器件的安全稳定运行至关重要.本文旨在从反常热传导的视角重新审视分数阶热弹耦合模型。反常热传导由第二声效... 详细信息

原子模拟和实验研究表明低维纳米材料具有反常热传导特性,建立唯象反常热弹耦合模型,研究强热传导导致的热力耦合响应,对微纳器件的安全稳定运行至关重要.本文旨在从反常热传导的视角重新审视分数阶热弹耦合模型。反常热传导由第二声效应引起,考虑波动热传导理论,建立了波动热传导与粘弹性理论的类比,阐明了Cattaneo-Vernotte模型和Green-Naghdi模型的关联.通过引入分数阶导数,构建了基于Cattaneo-Vernotte和Green-Naghdi理论的分数阶热弹耦合模型。数值结果表明:对分数阶次区间[O,1],分数阶Cattaneo-Vernotte(FCV)I模型和分数阶Green-Naghdi(FGN)I-III模型都能预测反常热弹耦合响应:比经典热弹性理论更高的温度和应力;温度和应力随时间的变化显示:FGNII模型在所有时间范围内都能得到反常响应.对Green-Naghdi模型及其分数阶模型的进一步系统研究,有助于揭示反常热传导和热弹耦合机理,并促进纳米材料的广泛应用.

关键词：粘弹性理论分数阶导数热弹耦合热弹性理论热传导低维纳米材料分数阶模型微纳器件

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Stiff dynamic absorbers for the vertical seismic protection of structures 8

Stiff dynamic absorbers for the vertical seismic protection ...

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8th International Conference on Computational Methods in Structural dynamics and Earthquake Engineering, COMPDYN 2021

作者： Kalogerakou, M.E. Kapasakalis, K.A. Antoniadis, I.A. Sapountzakis, E.J. Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens Zografou Campus AthensGR-157 80 Greece Dynamics and Structures Laboratory Mechanical Design and Control Systems Section Mechanical Engineering Department National Technical University of Athens Zografou Campus AthensGR-157 80 Greece

The majority of the existing seismic protection systems and techniques are related to horizontal ground motions, while there are only a few vertical seismic protection systems. The main reason is due to the conflict concerning the demand for isolation stiffness. More specifically, a vertical isolated system must have sufficient vertical rigidity to sustain the weight of the isolated object/system and retain the static vertical deflection in reasonable limits. On the other hand, the isolated system must also have enough flexibility to isolate the accelerations. In order to overcome this difficulty, a novel vertical seismic absorber system is proposed, that combines a Quasi-Zero Stiffness (QZS) design including negative stiffness elements, an enhanced Tunned Mass Damper (TMD) and an inerter. The QZS oscillator manages to maintain the vertical rigidity of the structure, the inerter manages to reduce the frequency of the system, without weakening the structure or increase the seismic load and the TMD is responsible for absorbing the external excitations, significantly increasing the effective damping. This way, the dynamic behavior of the system is improved, in terms of absolute accelerations, and simultaneously, the static settlements are retained at any desired level. The design is based on engineering criteria, and the excitation input is selected according to the seismic design codes. © 2021 COMPDYN Proceedings.

关键词： Damping

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TRANSITION FROM PRELIMINARY TO DETAILED DESIGN OF A HIGHLY ELASTIC SOLAR ELECTRIC AIRCRAFT 19

TRANSITION FROM PRELIMINARY TO DETAILED DESIGN OF A HIGHLY E...

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19th International Forum on Aeroelasticity and Structural dynamics, IFASD 2022

作者： Voß, Arne Koch, Christopher Niemann, Steffen Mantei, Marius Handojo, Vega Weiser, Christian DLR - German Aerospace Center Institute of Aeroelasticity Bunsenstr. 10 Göttingen37073 Germany DLR - German Aerospace Center Institute of Composite Structures and Adaptive Systems Lilienthalplatz 7 Braunschweig38108 Germany DLR - German Aerospace Center Institute of System Dynamics and Control Münchener Straße 20 Weßling82234 Germany

ISBN: (纸本)9788409423538

This work presents the evolution of the aeroelastic modeling of a solar electric aircraft. The dimensions (wing span of ˜27.0 m) and the extreme light-weight construction (wing loading ˜4.0 kg/m2) results in a highly flexible aircraft, making aeroelastic analyses mandatory in all stages of the aircraft design. Comparing the preliminary with the detailed design phase, the aeroelastic models are significantly improved in their level of detail. Still, the models show similar structural dynamic characteristics and a comparable loading, e.g. in terms of wing bending and torsional moments, where the highest loads are caused by similar load cases. For the sizing, the analytic approach from the preliminary design is backed-up with numerical analyses using a detailed FE model. A comprehensive flutter analysis confirms the findings obtained from a flutter check during the preliminary design. Finally, first structural tests are prepared to validate the models. © Proceedings of the International Forum of Aeroelasticity and Structural dynamics 2022, IFASD 2022.

关键词： Aeroelasticity

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Overview of collaborative multi-fidelity multidisciplinary design optimization activities in the dlr project victoria

Overview of collaborative multi-fidelity multidisciplinary d...

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AIAA AVIATION 2020 FORUM

作者： Görtz, S. Abu-Zurayk, M. Ilić, Č. Wunderlich, T. Keye, S. Schulze, M. Klimmek, T. Kaiser, C. Süelözgen, Ö. Kier, T. Schuster, A. Dähne, S. Petsch, M. Kohlgrüber, D. Häßy, J. Mischke, R. Weinert, A. Knechtges, P. Gottfried, S. Hartmann, J. Fröhler, B. Institute of Aerodynamics and Flow Technology Braunschweig38108 Germany Institute of Aeroelasticity Göttingen37073 Germany Institute of System Dynamics and Control Weßling82234 Germany Institute of Composite Structures and Adaptive Systems Braunschweig38108 Germany Institute of Structures and Design Stuttgart70569 Germany Institute of Propulsion Technology Cologne51147 Germany Institute for Software Technology Cologne51147 Germany Institute of Software Methods for Product Virtualization Dresden01062 Germany Institute of System Architecture in Aeronautics Hamburg21129 Germany

ISBN: (数字)9781624105982

ISBN: (纸本)9781624105982

The DLR project VicToria brings together disciplinary methods and tools of different fidelity for collaborative multidisciplinary design optimization (MDO) of long-range passenger aircraft configurations, necessitating the use of high-performance computing. Three different approaches are being followed to master complex interactions of disciplines and software aspects: an integrated aero-structural wing optimization based on high-fidelity methods, a multi-fidelity gradient-based approach capable of efficiently dealing with many design parameters and many load cases, and a many-discipline highly-parallel approach, which is a novel approach towards computationally demanding and collaboration intensive MDO. The XRF-1, an Airbus provided research aircraft configuration representing a typical long-range wide-body aircraft, is used as a common test case to demonstrate the different MDO strategies. Additional results are presented for the NASA Common Research Model (CRM) to show their flexibility. Parametric disciplinary models are used in terms of overall aircraft design synthesis, loads analysis, flutter, structural analysis and optimization, engine design, and aircraft performance. The different MDO strategies are shown to be effective in dealing with complex, real-world MDO problems in a highly collaborative, cross-institutional design environment, involving many disciplinary groups and experts and a mix of commercial and in-house design and analysis software. © 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Research aircraft

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Cybermatrix protocol: A novel approach to highly collaborative and computationally intensive multidisciplinary aircraft optimization

Cybermatrix protocol: A novel approach to highly collaborati...

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AIAA AVIATION 2020 FORUM

作者： Ilić, Časlav Merle, Andrei Abu-Zurayk, Mohammad Görtz, Stefan Leitner, Martin Süelözgen, Özge Kier, Thiemo Schulze, Matthias Klimmek, Thomas Kaiser, Christoph Martin, David Quero Schuster, Andreas Petsch, Michael Kohlgrüber, Dieter Häßy, Jannik Becker, Richard-Gregor Gottfried, Sebastian Fröhler, Benjamin Hartmann, Johannes Tröltzsch, Anke Institute of Aerodynamics and Flow Technology Braunschweig Germany DLR Institute of System Dynamics and Control Weßling Germany DLR Institute of Aeroelasticity Göttingen Germany DLR Institute of Composite Structures and Adaptive Systems Braunschweig Germany DLR Institute of Structures and Design Stuttgart Germany DLR Institute of Propulsion Technology Cologne Germany DLR Institute of Software Methods for Product Virtualization Dresden Germany DLR Institute of System Architectures in Aeronautics Hamburg Germany DLR Institute of Software Technology Cologne Germany

ISBN: (数字)9781624105982

ISBN: (纸本)9781624105982

This paper presents the cybermatrix protocol, a novel approach to multidisciplinary design optimization in the contex of many involved disciplinary experts and high use of high-performance computing resources. The approach is presented from its formal mathematical background to actual on-disk implementation of a running process. As the demonstration case, a twin-engine long-range transport aircraft is optimized. Two optimization processes are shown, an overall aircraft optimization (wing planform free) and a local parameter optimization (fixed planform), with five disciplines between them: overall aircraft wing planform design, aircraft synthesis and mission evaluation, aeroelastic wing airfoil design (RANS flow, trimmed static-aeroelastic state), maneuver loads evaluation and structural wing design (panel aerodynamics, global shell-element FEM model), and gust loads evaluation and selection (panel aerodynamics, dynamic FEM beam model). Optimized solutions are in line with those expected from previous studies under similar conditions, serving as a validation point for the new approach. Moreover, since the approach can deal flexibly with a higher-complexity loads subprocesses, such as configuration-specific selection of design load cases, also some interesting new effects are seen in optimized designs. © 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Design aids

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Stability and control investigations in early stages of aircraft design 36th

Stability and control investigations in early stages of airc...

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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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Sub-Preferential Rotational Wave Beaming in Structurally Rhombus Re-Entrant Honeycombs

SSRN

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SSRN 2023年

作者： Zhu, Zhiwei Deng, Zichen State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi'An710072 China

Rotational waves frequently manifest in micro-structured materials and are often coupled with classical shear or longitudinal wave modes. In this study, a distinctive isolated optical branch, exhibiting very high polarization index related to joint rotation motion, is found in dispersion diagram of elastic wave propagation in structurally rhombus re-entrant honeycomb (SSRH). Through an analysis of group velocity, we further explore the wave beaming of the rotational wave propagation within the SRRH, and intriguingly, observe the emergence of sub-preferential wave beaming occurring along the short diagonal directions. This dynamic anisotropic phenomenon stems from the intricate interplay between wave frequency and structural topology. To elucidate the underlying dynamic anisotropy of rotational waves, we propose a simple rigid-spring model and derive an anisotropic coefficient that precisely captures the intricate frequency-structure coupling behavior. The obtained anisotropic coefficient unveils the formation of sub-preferential directions of the rotational wave within the SRRH. Our findings transcend the elucidation of dynamic anisotropy in lattice materials, extending to practical implications encompassing the manipulation of elastic wave propagation and the design of waveguides. © 2023, The Authors. All rights reserved.

关键词： Anisotropy

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COLLABORATIVE HIGH FIDELITY AND HIGH PERFORMANCE COMPUTING-BASED MDO STRATEGIES FOR TRANSPORT AIRCRAFT DESIGN 32

COLLABORATIVE HIGH FIDELITY AND HIGH PERFORMANCE COMPUTING-B...

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32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021

作者： Görtz, S. Ilić, Č. Abu-Zurayk, M. Wunderlich, T. Schulze, M. Klimmek, T. Süelözgen, Ö. Kier, T. Schuster, A. Dähne, S. Petsch, M. Häßy, J. Becker, R.-G. Siggel, M. Kleinert, J. Mischke, R. Gottfried, S. Institute of Aerodynamics and Flow Technology Lilienthalplatz 7 Braunschweig38108 Germany Institute of Aeroelasticity Bunsenstr. 10 Göttingen37073 Germany Institute of System Dynamics and Control Münchenerstr. 20 Weßling 82234 Germany Institute of Composite Structures and Adaptive Systems Lilienthalplatz 7 Braunschweig38108 Germany Institute of Structures and Design Pfaffenwaldring 38-40 Stuttgart70569 Germany Institute of Propulsion Technology Linder Höhe Cologne51147 Germany Simulation and Software Technology Linder Höhe Cologne51147 Germany Institute of Software Methods for Product Virtualization Dresden01062 Germany

ISBN: (纸本)9783932182914

Aviation is undergoing a transformation, fueled by the Corona pandemic, and methods to evaluate new technologies for more economical and environment-friendly flight in a timelier manner and to enable new aircraft to be designed (almost) exclusively using computers are sought after. The DLR project Victoria brings together disciplinary methods and tools of different fidelity for collaborative multidisciplinary design optimization (MDO) of long-range passenger aircraft configurations, necessitating the use of high-performance computing. Three different approaches are being followed to master complex interactions of disciplines and software aspects: an integrated aero-structural wing optimization based on high-fidelity methods, a multi-fidelity gradient-based approach capable of efficiently dealing with many design parameters and many load cases, and a many-discipline highly-parallel approach, which is a novel approach towards computationally demanding and collaboration intensive MDO. The XRF-1, an Airbus provided research aircraft configuration representing a typical long-range wide-body aircraft, is used as a common test case to demonstrate the different MDO strategies. Parametric disciplinary models are used in terms of overall aircraft design synthesis, loads analysis, flutter, structural analysis and optimization, engine design, and aircraft performance. The different MDO strategies are shown to be effective in dealing with complex, real-world MDO problems in a highly collaborative, cross-institutional design environment, involving many disciplinary groups and experts and a mix of commercial and in-house design and analysis software. © 2021 32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021. All rights reserved.

关键词： Research aircraft

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基于子区域的结构拓扑优化并行策略

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Acta Mechanica Sinica 2023年第9期39卷 114-125页

作者：赵子龙荣毅燕翌冯西桥谢亿民 Institute of Solid Mechanics School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100191China Centre for Innovative Structures and Materials School of EngineeringRMIT UniversityMelbourne 300lAustralia Department of Engineering Mechanics MIIT Key Laboratory of Dynamics and Control of Complex SystemsNorthwestern Polytechnical UniversityXi'an710072China Institute of Biomechanics and Medical Engineering Department of Engineering MechanicsTsinghua UniversityBejing 100084China

结构拓扑优化在过去的三十年里经历了巨大的发展,充分利用高性能计算资源有助于拓宽拓扑优化在大规模设计问题中的应用。本文提出了一种针对一般三维拓扑优化的基于子区域的并行策略。通过子区域划分、矩阵运算、引入单元硬杀算法,优化... 详细信息

结构拓扑优化在过去的三十年里经历了巨大的发展,充分利用高性能计算资源有助于拓宽拓扑优化在大规模设计问题中的应用。本文提出了一种针对一般三维拓扑优化的基于子区域的并行策略。通过子区域划分、矩阵运算、引入单元硬杀算法,优化过程得以显著提速.将该策略整合进高效、简洁的Python代码;该代码可适用于任意形状的设计域.附录一中给出的完整代码,易于扩展,扩展后可解决多类优化问题.通过求解四个柔度最小化问题展示了该策略的高效性.本研究在机械工程、先进制造,以及建筑设计等领域有潜在的应用价值.

关键词：并行策略高性能计算子区域划分最小化问题结构拓扑优化 Python 设计域建筑设计

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