Structural Dynamics Modeling of Helicopter Blades for Computational Aeroelasticity PDF Download
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Author: Tao Cheng
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
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Book Description
Author: Tao Cheng
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
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Book Description
Author: Richard L. Bielawa
Publisher: Amer Inst of Aeronautics &
ISBN: 9781563470318
Category : Aeroelasticity.
Languages : en
Pages : 562
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Book Description
Drawing on his extensive experience as a practicing engineer, designer, educator, and researcher in rotorcraft, the author presents a comprehensive account of the fundamental concepts of structural dynamics and aeroelasticity for conventional rotary wing aircraft, as well as for the newly emerging tilt-rotor and tilt-wing concepts. Intended for use in graduate-level courses and by practicing engineers, the volume covers all of the important topics needed for the complete understanding of rotorcraft structural dynamics and aeroelasticity, including basic analysis tools, rotating beams, gyroscopic phenomena, drive system dynamics, fuselage vibrations, methods for controlling vibrations, dynamic test procedures, stability analysis, mechanical and aeromechanical instabilities of rotors and rotor-pylon assemblies, unsteady aerodynamics and flutter of rotors, and model testing. The text is further enhanced by the inclusion of problems in each chapter.
Author: Michael D. Rudy
Publisher:
ISBN:
Category :
Languages : en
Pages : 162
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Book Description
In the investigation of the structural dynamic problems associated with a helicopter rotor blade, a fully articulated rotor blade is considered in the analysis of the aeroelastic model. Therefore, there are three degrees of freedom considered; flapping, torsion, and lead-lag. The flapping and torsional motions are coupled inertially and the lead-lag motion is uncoupled from the other motions. The study is concerned with developing an aeroelastic model which takes into consideration the effects of the shearing force and rotary inertia upon the fundamental frequencies and mode shapes of the rotor blade. Also, the effect of inertial coupling between flapping and torsion on the fundamental frequencies and mode shapes is considered. (Author).
Author: Eleanor C. Wynne
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 232
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Book Description
Author: Bishnujee Singh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Unlike aerofoil-shaped aircraft such as fighter jet or aircraft with aerofoil parts such as wings that use aerofoil lift force for flight and most importantly; have a lot of research material about their aeroelastic behavior easily accessible in the public domain, the tandem rotor helicopter uniquely relies entirely on its rotor blades for lift force during flight and most importantly; has got hardly any trace of research material about its aeroelastic behaviour in the public domain. Aeroelastic disturbances that are associated with more sophisticated heavy-duty Army aircraft such as the tandem rotor helicopter are capable of generating disturbances that are sufficiently violent to cause the almost instantaneous failure of the structure of the helicopter. This studythus aims to analytically model and establish a relation between the nature and variation of the external aerodynamic environment of a helicopter with tandem rotor blades and its internal structural dynamics characteristics, which would be modeled as a series of masses connectedby springs and dampers. This will, in turn, enable the prediction and thus anticipation, through analytic modelling and estimation of acting loads and changes of stiffness and deformation of the sections in and across the helicopter; of aerodynamic safety and failure criteria such as thepitching velocity margin, rolling velocity margin and the margin of the safe payload eccentricity in the fuselage and also enable suggest possible test fixes during the modeling and analysis of the aeroelasticity of the helicopter. The study also aims to analyze the effect of the variation ofthe structural flexibility of the segments of the tandem rotor helicopter and the distribution of loads in the body structure of the helicopter. The necessity to produce better tandem rotor helicopters that have low structural vibration levels, low noise, and enhanced performance willcontinue to motivate researchers all around the world and aeromechanics to develop innovative approaches for the solution of these aeroelasticity challenges. This study will thus contribute to the rare research material about the aeroelastic behavior of tandem rotor helicopters accessibleto the public domain.
Author: Kyle Brian Collins
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages :
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Book Description
New helicopter rotor designs are desired that offer increased efficiency, reduced vibration, and reduced noise. This problem is multidisciplinary, requiring knowledge of structural dynamics, aerodynamics, and aeroacoustics. Rotor optimization requires achieving multiple, often conflicting objectives. There is no longer a single optimum but rather an optimal trade-off space, the Pareto Frontier. Rotor Designers in industry need methods that allow the most accurate simulation tools available to search for Pareto designs. Computer simulation and optimization of rotors have been advanced by the development of "comprehensive" rotorcraft analysis tools. These tools perform aeroelastic analysis using Computational Structural Dynamics (CSD). Though useful in optimization, these tools lack built-in high fidelity aerodynamic models. The most accurate rotor simulations utilize Computational Fluid Dynamics (CFD) coupled to the CSD of a comprehensive code, but are generally considered too time consuming where numerous simulations are required like rotor optimization. An approach is needed where high fidelity CFD/CSD simulation can be routinely used in design optimization. This thesis documents the development of physics based rotor simulation frameworks. A low fidelity model uses a comprehensive code with simplified aerodynamics. A high fidelity model uses a parallel processor capable CFD/CSD methodology. Both frameworks include an aeroacoustic simulation for prediction of noise. A synergistic process is developed that uses both frameworks together to build approximate models of important high fidelity metrics as functions of certain design variables. To test this process, a 4-bladed hingeless rotor model is used as a baseline. The design variables investigated include tip geometry and spanwise twist. Approximation models are built for high fidelity metrics related to rotor efficiency and vibration. Optimization using the approximation models found the designs having maximum rotor efficiency and minimum vibration. Various Pareto generation methods are used to find frontier designs between these two anchor designs. The Pareto anchors are tested in the high fidelity simulation and shown to be good designs, providing evidence that the process has merit. Ultimately, this process can be utilized by industry rotor designers with their existing tools to bring high fidelity analysis into the preliminary design stage of rotors.
Author: Evangelos J. Sapountzakis
Publisher: Springer Nature
ISBN: 9811580499
Category : Technology & Engineering
Languages : en
Pages : 1203
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Book Description
This book presents the select proceedings of the 14th International Conference on Vibration Problems (ICOVP 2019) held in Crete, Greece. The volume brings together contributions from researchers working on vibration related problems in a wide variety of engineering disciplines such as mechanical engineering, wind and earthquake engineering, nuclear engineering, aeronautics, robotics, and transport systems. The focus is on latest developments and cutting-edge methods in wave mechanics and vibrations, and includes theoretical, experimental, as well as applied studies. The range of topics and the up-to-date results covered in this volume make this interesting for students, researchers, and professionals alike.
Author: Khin-yong Lam
Publisher: World Scientific
ISBN: 9814553743
Category :
Languages : en
Pages : 1556
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Book Description
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723509667
Category :
Languages : en
Pages : 440
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Book Description
This report describes the development of an aeroelastic analysis capability for composite helicopter rotor blades with straight and swept tips, and its application to the simulation of helicopter vibration reduction through structural optimization. A new aeroelastic model is developed in this study which is suitable for composite rotor blades with swept tips in hover and in forward flight. The hingeless blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. Arbitrary cross-sectional shape, generally anisotropic material behavior, transverse shears and out-of-plane warping are included in the blade model. The nonlinear equations of motion, derived using Hamilton's principle, are based on a moderate deflection theory. Composite blade cross-sectbnal properties are calculated by a separate linear, two-dimensional cross section analysis. The aerodynamic loads are obtained from quasi-steady, incompressible aerodynamics, based on an implicit formulation. The trim and steady state blade aeroelastic response are solved in a fully coupled manner. In forward flight, where the blade equations of motion are periodic, the coupled trim-aeroelastic response solution is obtained from the harmonic balance method. Subsequently, the periodic system is linearized about the steady state response, and its stability is determined from Floquet theory. Yuan, K. A. and Friedmann, P. P. Unspecified Center NASA-CR-4665, NAS 1.26:4665 NAG1-833; RTOP 505-63-36-06...
Author: A. R. S. Bramwell
Publisher: Elsevier
ISBN: 0080528309
Category : Technology & Engineering
Languages : en
Pages : 403
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Book Description
Since the original publication of 'Bramwell's Helicopter Dynamics' in 1976, this book has become the definitive text on helicopter dynamics and a fundamental part of the study of the behaviour of helicopters. This new edition builds on the strengths of the original and hence the approach of the first edition is retained. The authors provide a comprehensive overview of helicopter aerodynamics, stability, control, structural dynamics, vibration, aeroelastic and aeromechanical stability. As such, Bramwell's Helicopter Dynamics is essential for all those in aeronautical engineering. THE single volume comprehensive guide for anyone working with helicopters Written by leading worldwide experts in the field
