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Effects of Spanwise Spacing on the Interaction of Tandem Pitching Hydrofoils

AIAA JOURNAL 2023年第11期61卷 5121-5131页

作者： Lee, David S. Hrynuk, John T. Moored, Keith W. Lehigh Univ Bethlehem PA 18015 USA DEVCOM Army Res Lab Aberdeen Proving Ground MD 21005 USA

The interaction between a pair of tandem in-line oscillating hydrofoils is presented. The hydrofoils undergo sinusoidal pitching about their leading edges with a fixed Strouhal number of St=0.25 and a Reynolds number of 10,000. The streamwise spacing, spanwise spacing, and phase offset between the hydrofoils are varied. Force measurements are employed to investigate changes in thrust, lift, spanwise force, power consumption, and propulsive efficiency. A method to mitigate confounding factors from connecting rod drag is employed using streamlined fairings. Near and far streamwise spacing regions are identified with a transition occurring near 0.875 chord lengths downstream. Decreasing streamwise spacing in the far region causes a rise in the maximum power consumption of the follower hydrofoil. Decreasing streamwise spacing in the near region results in an opposite trend, with a sharp drop in maximum average power consumption by the follower. An empirical model for power consumption of the follower is developed. Increased spanwise spacing is found to weaken the interaction between the hydrofoils, driving them toward their isolated performance. This phenomenon is related to the spanwise contraction of the wake shed by the leader and is a function of the overlap of the wake region impacting the follower.

关键词： Watercraft Karman Vortex Street Free Stream Velocity Propulsive Efficiency Aircraft Wing design Wing Planforms NACA 0012 Electric Motors structural design and development Fixed Wing Aircraft

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Image-Driven Intelligent Prediction of Buckling Behavior for Geometrically Imperfect Cylindrical Shells

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AIAA JOURNAL 2023年第5期61卷 2266-2280页

作者： Hao, Peng Duan, Yuhui Liu, Dachuan Yang, Hao Liu, Debo Wang, Bo Dalian Univ Technol State Key Lab Struct Anal Ind Equipment Key Lab Digital Twin Ind Equipment Dept Engn Mech Dalian 116023 Peoples R China Beijing Inst Astronaut Syst Engn Beijing 100076 Peoples R China

Thin-walled cylindrical shells are key load-carrying components for aerospace structures. Axial compression is the most common load for cylindrical shells;however, critical buckling loads obtained experimentally are significantly lower than the theoretical values, owing to the presence of initial geometric imperfections (GIs). Previous studies often determined only the knockdown factor through the statistics of experimental data;it is an approximate lower limit of the load-carrying capacity and cannot accurately predict the buckling mode in real time. In this paper, an image-driven framework for the intelligent prediction of buckling load and mode based on measured GIs is proposed. First, through measured samples and the random field method, the GI data pool is obtained. Subsequently, two convolutional neural network (CNN) models are trained to predict the buckling load and mode for cylindrical shells, respectively. The active learning strategy is adopted to discern beneficial sample sets and enhance the prediction accuracy and training speed of the CNN models. A numerical example demonstrates that the proposed framework can effectively predict the buckling behavior of cylindrical shells with GIs. Furthermore, using the proposed prediction framework, it was observed that a common feature of unfavorable GIs is a large fluctuation in magnitude along the axial direction.

关键词： Cylindrical Shell Structures Buckling Analysis Convolutional Neural Network Numerical Analysis Finite Element Modeling Statistical Analysis Mathematical Analysis structural design and development Machine Learning Aerospace Engineering

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Multidisciplinary structural Optimization of Low-Pyroshock Separation Nuts for Aerospace

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JOURNAL OF SPACECRAFT AND ROCKETS 2023年第2期60卷 508-519页

作者： Wu, Yadong Lu, Yufan Yang, Hao Liu, Yichang Zhou, Mingdong Beijing Inst Astronaut Syst Engn Beijing 1000076 Peoples R China Shanghai Jiao Tong Univ Sch Mech Engn Shanghai Key Lab Digital Manufacture Thin Walled S 800 DongChuan Rd Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Key Lab Space Phys Beijing Shanghai 200240 Peoples R China

This paper presents a multidisciplinary structural optimization approach to design separation nuts with low-level pyroshock responses for aerospace. A parametric modeling method is developed to automatically construct a multibody finite element model for separation nuts according to the predefined structural parameters. A new explicit dynamics analysis workflow tailored to separation nuts is proposed to simulate the pyroshock environment efficiently. Based on a backpropagation neuron network technique, certain surrogate models are established to describe the equivalence relationship between the structural parameters and the multidisciplinary structural responses including the pyroshock, the bending stiffness, and the structural weight. Finally, a pyroshock minimization problem with the constraints of structural weight and bending stiffness is solved by using a genetic algorithm, resulting in an optimized low-pyroshock separation nut design. The comparison between the optimized structure and a reference structure shows the effectiveness of the proposed approach.

关键词： structural design and development structural Analysis Finite Element Analysis Numerical Analysis Genetic Algorithm Artificial Neural Network Mechanical and structural Vibrations Fluid Structure Interaction Finite Element Software Computational Fluid Dynamics

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development of Deep Convolutional Neural Network for structural Topology Optimization

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AIAA JOURNAL 2023年第3期61卷 1366-1379页

作者： Seo, Junhyeon Kapania, Rakesh K. Virginia Polytech Inst & State Univ Dept Aerosp & Ocean Engn Blacksburg VA 24060 USA

This research develops a highly effective deep-learning-based surrogate model that can provide the optimum topologies of 2D and 3D structures. In general, structural topology optimization requires plenty of computations because of a large number of finite element analyses to obtain optimal structural layouts by reducing the weight and satisfying the constraints. Therefore, many researchers have developed a deep-learning-based model using the initial static analysis results to predict the optimum designs. However, these studies still considered relatively simple example problems, such as a cantilever plate and MBB beam, even though they required a large number of data to achieve an accurate surrogate model for the simple application. To overcome these limitations, we propose a new framework, which 1) efficiently uses limited data by normalizing it and 2) employs a surrogate model capable of handling more practical cases, such as a 2D panel and 3D stiffened panel subjected to a distributed load, and can be used for local-global structural optimization. In all cases, the developed surrogate models can predict the optimum layouts with structural performance levels equal to those of the structures considered to be ground truths. Also, when the optimal structures were obtained using the proposed method, the total calculation time was reduced by 98% as compared to conventional topology optimization once the convolutional neural network had been trained.

关键词： Numerical Integration structural Analysis structural design and development Finite Element Modeling Image Processing Topology Optimization Machine Learning Finite Element Model Data Post-Processing structural Optimization Convolutional Neural Network

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Bioinspired Smart Helical Antenna: Variable Configuration design and Application

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AIAA JOURNAL 2023年第9期61卷 4214-4219页

作者： Zhang, Zeyi Qiu, Xinghan Zhang, Lamei Wang, Changguo Harbin Inst Technol Sch Astronaut Natl Key Lab Sci & Technol Adv Composites Special Harbin 150001 Peoples R China Harbin Inst Technol Sch Elect & Informat Engn Harbin 150001 Peoples R China

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Fundamentals Of High Accuracy Inertial Navigation 1st

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丛书名： Progress in Astronautics and Aeronautics

1997年

作者： Averil B. Chatfield

ISBN: (数字)9781600866463

ISBN: (纸本)9781563472435

The primary focus of Fundamentals of High Accuracy Inertial Navigation is on the physical and mathematical principles forming the basis for inertial navigation. It differs from other books on the subject by treating aspects of the blend of inertial navigation technology and geodesy. Accuracy criteria and evaluation are also discussed. Fundamentals of High Accuracy Inertial Navigation is divided into three parts: inertial navigation, inertial navigation with aids, and accuracy analysis. The first two parts are designed to give the reader an understanding of the fundamentals without requiring knowledge of the statistical analysis techniques involved in determining the effects of errors on accuracy. The third part defines the criteria for determining accuracy and then leads the reader through the complex process of that determination. This book is intended for the third- or fourth-year engineering student, as well as professional engineers or scientists trained in mathematics, control theory, analytical mechanics, geodesy, or physics, who have a need for understanding the basic principles of inertial navigation technology.

关键词： Aerodynamics Aeronautical Engineering Aeronautics Air Navigation Aircraft Navigation Systems Altitudes in Aviation Applied Mathematics Astronomy Avionics Avionics Computers Bearings (Mechanical) Celestial Mechanics Classical Mechanics Computational Fluid Dynamics Computer Programming and Language Computing and Informatics Computing, Information, and Communication Control Systems Control Theory Coordinate System Doppler Effect Earth Observation Satellite Earth Sciences Electrodynamics Electromagnetic Radiation Electromagnetism Elementary Algebra Fault Detection and Isolation Feedback Control Finite Element Method Fluid Dynamics Fluid Flow Properties Fluid Mechanics General Physics Geometry Functions Geophysics Global Positioning System Guidance, Navigation, and Control Systems Gyroscopes Hydraulic Fluid Hydraulics Kalman Filter Mathematical Analysis Mechanical and structural Vibrations Monte Carlo Method Navigational Guidance Newton's Laws of Motion Numerical Analysis Planetary Atmospheres Planetary Science and Exploration Planets Satellite Navigation Systems Satellites Sensors Signal Processing Solar Physics Solar Wind Space Flight Tracking and Data Network Space Science and Technology Space Systems and Vehicles Spacecraft Guidance and Control Spacecrafts structural Analysis structural design and development structural Engineering structural Kinematics and Dynamics Structures, design and Test Torsional Vibration Transducers Tribology and Bearing design Vibration Measuring Instruments

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Advanced Dynamics Har/Dskt

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丛书名： AIAA Education Series

1997年

作者： Shuh-Jing (Benjamin) Ying

ISBN: (数字)9781600861307

ISBN: (纸本)9781563472244

Advanced Dynamics is recognized as an important subject of study for all engineering students and professionals in competitive university programs and throughout the industry. This textbook adeptly explains the fundamental laws of motion, but goes a step beyond by covering new topics such as gyroscopic effects, missile trajectories, interplanetary missions, multistage rockets, and use of numerical methods. In addition, theories such as the rotation operator are taken to a new degree and developed further, far surpassing comparable *** book balances theory and application and relates all subjects to practical problems, real-world situations, and recent advances that affect everyday life. This text distinguishes itself with a more complete introduction to recent developments in dynamics, new and practical applications to help the reader remember key theories and uses, and an appreciation that the subject matter is riddled with ongoing problems that need new solutions. These distinguishing features make Advanced Dynamics more complete, interesting, and understandable than existing textbooks and resource materials. Problems appear at the end of each chapter, and a complimentary solutions manual is available for professors. Advanced Dynamics is also written for those engineers who want to update their knowledge and stay current on changes in the field, but do not have the opportunity to attend formal classes. The reader will take away a thorough understanding of the foundation of mechanical engineering, which is necessary to read and assimilate scholarly papers and leading articles published in journals and peer-reviewed magazines.

关键词： Aerodynamics Aeronautical Engineering Aeronautics Aircraft Operations Aircraft Operations and Technology Aircraft Stability and Control Aircrafts Applied Mathematics Beam (Structures) Classical Mechanics Computational Fluid Dynamics Computer Programming and Language Computing and Informatics Computing, Information, and Communication Coordinate System Earth Observation Satellite Elementary Algebra Energy Energy Forms Energy Forms, Production and Conversion Energy Storage and Batteries Finite Element Method Flexible and Active Structures Flight Control Surfaces Fluid Dynamics Fluid Flow Properties Fluid Mechanics General Physics Geometry Functions Gyroscopes Launch Vehicles Material Properties Materials and structural Mechanics Mathematical Analysis Mechanical and structural Vibrations Multistage Rocket Newton's Laws of Motion Numerical Analysis Planetary Science and Exploration Planets Rotor Dynamics Runge-Kutta Methods Satellites Shell Structures Solid Mechanics Space Launch Systems Space Missions Space Probe Space Science and Technology Space Systems Space Systems and Vehicles Space Vehicle Spacecrafts Stress-Strain Analysis structural Analysis structural design and development structural Engineering structural Kinematics and Dynamics structural Mechanics Structures, design and Test Uncrewed Spacecraft Vibration Measuring Instruments Weather Satellite

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Thermal Structures for Aerospace Applications

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丛书名： AIAA Education Series

1996年

作者： Earl A. Thornton

ISBN: (数字)9781600862540

ISBN: (纸本)9781563471902

As aircraft flight speeds have increased and orbital missions have mandated complex space structures, the need for a deeper understanding of aerospace thermal structural behavior has grown. The purpose of this book is to study the basic problems of complex computer analyses as they relate to this behavior. With in-depth presentations, this book sets out to allow readers to develop an understanding of the basic physical behavior of thermal structures, gain an appreciation for the role of classical engineering thermal and stress analyses, and apply computational methods to provide insight into realistic behavior.

关键词： Aerodynamics Aeroelasticity Aeronautical Engineering Aeronautics Aerothermodynamics Airspeed Beam (Structures) Boundary Layers Buckling Analysis Composite Materials Computational Fluid Dynamics Conservation of Momentum Equations Continuum Mechanics Convection Coolant Cooling Technology Cylindrical Shell Structures Deformation Deformation Mechanisms Equations of Fluid Dynamics FEM Elements Finite Element Method Flexible and Active Structures Flow Regimes Fluid Dynamics Fluid Flow Properties Heat Conduction Heat Exchangers Heat Transfer Heating System Heating, Ventilating, and Air Conditioning Material Properties Materials Materials and structural Mechanics Mechanical Properties Mechanical and structural Vibrations Numerical Heat Transfer Plastic Deformation Plasticity Radiative Heat Transfer Shell Structures Skin Friction Solar Heating Solid Mechanics Stress-Strain Analysis structural Analysis structural design and development structural Dynamics and Characterization structural Engineering structural Mechanics structural Modeling and Simulation Structures, design and Test Thermal Control and Protection Thermal Effects Thermal Measurement Thermal Modeling and Analysis Thermodynamic Properties Thermodynamics Thermophysical Properties Thermophysics and Heat Transfer Torsional Vibration Trusses Vortex Dynamics

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Highly Flexible Structures: Modeling, Computation, and Experimentation

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丛书名： AIAA Education Series

2007年

作者： P.Frank Pai

ISBN: (数字)9781600861925

ISBN: (纸本)9781563479175

This book provides new methods and advanced experimental techniques for the design, analysis, and testing of highly flexible deployable/inflatable structures (HFSs), including systematic nonlinear modeling approaches, newly developed geometrically exact structural theories, numerically exact solution methods, fully nonlinear finite element techniques, and non-contact techniques for static and dynamic testing. Chapter 1 summarizes characteristics of HFSs, points out challenging modeling and analysis issues, and presents state-of-the-art measurement systems for testing HFSs. Chapter 2 presents the fundamentals of structural mechanics to prepare the reader for geometrically exact modeling of HFSs. Chapter 3 presents the fundamentals of nonlinear finite element analysis and the multiple shooting method of solving nonlinear ordinary differential equations for numerically exact solutions. The book then proceeds in treating different structural systems from simple 1D systems (trusses and cables in chapter 4, and beams in chapter 5), to 2D systems (plats and shells in chapter 6, and membranes in chapter 7), and to complex systems (smart structures in chapter 8). The author uses the lowest possible level of mathematical complexity as possible to convey concepts. In addition to more than 350 descriptive illustrations, the accompanying DVD contains computer programs and videos of experiments. These programs and visual tools aid the reader in quickly developing a basic understanding. The text, chapter questions, solutions manual, and accompanying CD will support a one-semester graduate-level course.

关键词： Beam (Structures) Buckling Analysis Classical Mechanics Computational Fluid Dynamics Computer Programming and Language Computer-Aided Manufacturing Computing and Informatics Computing, Information, and Communication Continuum Mechanics Cylindrical Shell Structures Deformation Dynamic Analysis FEM Elements Failure Analysis Fatigue Analysis Finite Element Method Finite Element Software Flexible and Active Structures Fluid Dynamics General Physics Hilbert-Huang Transform Material Properties Materials Materials and structural Mechanics Mechanical Properties Mechanical and structural Vibrations Membrane Structures Newton's Laws of Motion Numerical Analysis Plastic Deformation Runge-Kutta Methods Shell Structures Signal Processing Smart Structures and Materials Solid Mechanics Stress-Strain Analysis structural Analysis structural design and development structural Dynamics and Characterization structural Engineering structural Kinematics and Dynamics structural Mechanics structural Modeling and Simulation structural System Structures, design and Test Trusses Vibration Measuring Instruments

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Liquid Rocket Engine Combustion Instability

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丛书名： Progress in Astronautics and Aeronautics

1995年

作者： William E. Anderson Vigor Yang

ISBN: (数字)9781600866371

ISBN: (纸本)9781563471834

Since the invention of the V-2 rocket during World War II, combustion instabilities have been recognized as one of the most difficult problems in the development of liquid propellant rocket engines. This book is the first published in the United States on the subject since NASA's Liquid Rocket Combustion Instability (NASA SP-194) in 1972. Improved computational and experimental techniques, coupled with a number of experiences with full-scale engines worldwide, have offered opportunities for advancement of the state of the art. In this book, experts cover four major subject areas: engine phenomenology and case studies, fundamental mechanisms of combustion instability, combustion instability analysis, and engine and component testing. Especially noteworthy is the inclusion of technical information from Russia and China - a first. Engineers and scientists in propulsion, power generation, and combustion instability will find the 20 chapters valuable as an extension of prior work and as a reference.

关键词： Aerodynamics Aeronautical Engineering Aeronautics Aircraft Engines Apollo Program Boosters Boundary Layers Chemical Kinetics Combustion Combustion Chambers Combustors Computational Fluid Dynamics Conservation of Momentum Equations Convection Energy Energy Conservation Energy Conversion Energy Forms Energy Forms, Production and Conversion Energy Production Enthalpy Equations of Fluid Dynamics Finite Difference Method Flow Regimes Fluid Dynamics Fluid Flow Properties Fluid Mechanics Fossil Fuels Fuel Injection Fuels Gas Turbine Heat Conduction Heat Engines Heat Transfer Heating, Ventilating, and Air Conditioning Ideal Gas Ignition Systems Liquid Fuels Liquid Rocket Propellant Liquid-Propellant Rocket Mass Spectroscopy Mass Transfer Mechanical and structural Vibrations Monte Carlo Method NASA NASA Facilities NASA Programs Non-Renewable Energy Nozzles Numerical Analysis Petroleum Planetary Science and Exploration Planets Propellant Propulsion and Power Reacting Flow Rocket Components Rocket Engine Rocket Propellant Rocket Propulsion Rocketry Rockets Shock Waves Solar System Moons Solid-Propellant Rocket Space Agencies Space Missions Space Science and Technology Space Shuttle Program Spectroscopy structural Analysis structural design and development structural Engineering Structures, design and Test Thermochemistry and Chemical Kinetics Thermodynamic Properties Thermodynamics Thermophysics and Heat Transfer Turbines Turbomachinery Turbulence Turbulence Models Vortex Dynamics

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