Nonlinear Dynamics in the Modeling of Helicopter Rotor Blade Lead/Lag Motion
Nonlinear Dynamics in the Modeling of Helicopter Rotor Blade Lead/Lag Motion

Author: Robert L. King

Publisher:

Published: 1999-06-01

Total Pages: 176

ISBN-13: 9781423543527

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Until recently, computer simulations of helicopter rotor dynamics have employed equations of motion that have been linearized or simplified. These modified equations of motion did not allow for the evaluation of nonlinear material properties in the rotor since higher order terms in the dynamics had been modified in the simplification process. With recent advances in both computer simulation hardware and symbolic mathematic manipulation software, the full nonlinear equations of motion may be utilized in helicopter rotor simulations. This dissertation reports on the use of the full nonlinear equations of motion in the analysis of rotor blade lead/lag motion and its effect on rotor hub and rigid body fulselage motion. Nonlinear modeling methods are implemented using Maple symbolic mathematic manipulation software and Matlab and Simulink computer simulation environments. Results are compared to the RAH- 66 Comanche Froude scale wind tunnel article and new methodologies evaluated in the search for a damperless rotor system that is free of ground and air resonance mechanical instabilities.

Bramwell's Helicopter Dynamics
Bramwell's Helicopter Dynamics

Author: A. R. S. Bramwell

Publisher: Elsevier

Published: 2001-04-06

Total Pages: 403

ISBN-13: 0080528309

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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

Surveys in Differential-Algebraic Equations IV
Surveys in Differential-Algebraic Equations IV

Author: Achim Ilchmann

Publisher: Springer

Published: 2017-03-08

Total Pages: 312

ISBN-13: 3319466186

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The present volume comprises survey articles on various fields of Differential-Algebraic Equations (DAEs) which have widespread applications in controlled dynamical systems, especially in mechanical and electrical engineering and a strong relation to (ordinary) differential equations. The individual chapters provide reviews, presentations of the current state of research and new concepts in - History of DAEs - DAE aspects of mechanical multibody systems - Model reduction of DAEs - Observability for DAEs - Numerical Analysis for DAEs The results are presented in an accessible style, making this book suitable not only for active researchers but also for graduate students (with a good knowledge of the basic principles of DAEs) for self-study.

Fundamentals of Helicopter Dynamics
Fundamentals of Helicopter Dynamics

Author: C. Venkatesan

Publisher: CRC Press

Published: 2014-08-19

Total Pages: 342

ISBN-13: 1466566345

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Helicopter Dynamics Introduced in an Organized and Systematic Manner A result of lecture notes for a graduate-level introductory course as well as the culmination of a series of lectures given to designers, engineers, operators, users, and researchers, Fundamentals of Helicopter Dynamics provides a fundamental understanding and a thorough overview of helicopter dynamics and aerodynamics. Written at a basic level, this text starts from first principles and moves fluidly onward from simple to more complex systems. Gain Valuable Insight on Helicopter Theory Divided into 11 chapters, this text covers historical development, hovering and vertical flight, simplified rotor blade model in flap mode, and forward flight. It devotes two chapters to the aeroelastic response and stability analysis of isolated rotor blade in uncoupled and coupled modes. Three chapters address the modeling of coupled rotor–fuselage dynamics and the associated flight dynamic stability, and provide a simplified analysis of the ground resonance aeromechanical stability of a helicopter. Explains equations derived from first principles and approximations Contains a complete set of equations which can be used for preliminary studies Requires a basic first–level course in dynamics, as well as a basic first–level course in aerodynamics Useful for any student who wants to learn the complexities of dynamics in a flying vehicle, Fundamentals of Helicopter Dynamics is an ideal resource for aerospace/aeronautical, helicopter, and mechanical/control engineers, as well as air force schools and helicopter/rotorcraft manufacturers.

Principles of Helicopter Aerodynamics with CD Extra
Principles of Helicopter Aerodynamics with CD Extra

Author: Gordon J. Leishman

Publisher: Cambridge University Press

Published: 2006-04-24

Total Pages: 860

ISBN-13: 9780521858601

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Written by an internationally recognized teacher and researcher, this book provides a thorough, modern treatment of the aerodynamic principles of helicopters and other rotating-wing vertical lift aircraft such as tilt rotors and autogiros. The text begins with a unique technical history of helicopter flight, and then covers basic methods of rotor aerodynamic analysis, and related issues associated with the performance of the helicopter and its aerodynamic design. It goes on to cover more advanced topics in helicopter aerodynamics, including airfoil flows, unsteady aerodynamics, dynamic stall, and rotor wakes, and rotor-airframe aerodynamic interactions, with final chapters on autogiros and advanced methods of helicopter aerodynamic analysis. Extensively illustrated throughout, each chapter includes a set of homework problems. Advanced undergraduate and graduate students, practising engineers, and researchers will welcome this thoroughly revised and updated text on rotating-wing aerodynamics.

Nonlinear Composite Beam Theory
Nonlinear Composite Beam Theory

Author: Dewey H. Hodges

Publisher: Progress in Astronautics and A

Published: 2006

Total Pages: 344

ISBN-13:

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From an authoritative expert whose work on modern helicopter rotor blade analysis has spanned over three decades, comes the first consistent and rigorous presentation of beam theory. Beginning with an overview of the theory developed over the last 60 years, Dr. Hodges addresses the kinematics of beam deformation, provides a simple way to characterize strain in an initially curved and twisted beam, and offers cross-sectional analysis for beams with arbitrary cross sections and composed of arbitrary materials. He goes on to present a way to accurately recover all components of cross-sectional strain and stress before providing a natural one-dimensional (1-D) theory of beams. Sample results for both cross-sectional and 1-D analysis are presented as is a parallel treatment for thin-walled beams.

Smart Helicopter Rotors
Smart Helicopter Rotors

Author: Ranjan Ganguli

Publisher: Springer

Published: 2015-12-16

Total Pages: 264

ISBN-13: 3319247689

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Exploiting the properties of piezoelectric materials to minimize vibration in rotor-blade actuators, this book demonstrates the potential of smart helicopter rotors to achieve the smoothness of ride associated with jet-engined, fixed-wing aircraft. Vibration control is effected using the concepts of trailing-edge flaps and active-twist. The authors’ optimization-based approach shows the advantage of multiple trailing-edge flaps and algorithms for full-authority control of dual trailing-edge-flap actuators are presented. Hysteresis nonlinearity in piezoelectric stack actuators is highlighted and compensated by use of another algorithm. The idea of response surfaces provides for optimal placement of trailing-edge flaps. The concept of active twist involves the employment of piezoelectrically induced shear actuation in rotating beams. Shear is then demonstrated for a thin-walled aerofoil-section rotor blade under feedback-control vibration minimization. Active twist is shown to be significant in reducing vibration caused by dynamic stall. The exposition of ideas, materials and algorithms in this monograph is supported by extensive reporting of results from numerical simulations of smart helicopter rotors. This monograph will be a valuable source of reference for researchers and engineers with backgrounds in aerospace, mechanical and electrical engineering interested in smart materials and vibration control. Advances in Industrial Control aims to report and encourage the transfer of technology in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. The series offers an opportunity for researchers to present an extended exposition of new work in all aspects of industrial control.