Download or read book Fluidic Flexible Matrix Composite Vibration Treatments for Helicopter Airframes and Rotor Blades written by Matthew Joseph Krott and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibrations caused by periodic and unsteady loading in rotorcraft must be minimized to maintain acceptable fatigue life in structural parts and ride quality for passengers and crew. Rotorcraft vibrations are typically addressed through some combination of passive and active solutions that focus on reducing steady-state vibrations at the n/rev frequency, where n is the number of rotor blades. Currently existing passive treatments are often heavy, bulky variations of the classical tuned vibration absorber. Active treatments either attempt to isolate the cabin from hub vibratory loads or reduce cabin vibrations using a set of actuators, but they are more difficult to implement because they require a power supply and controller. This research covers the modeling, design, and experimental verification of fluidic flexible matrix composite (F2MC) vibration treatments for two main rotorcraft applications: airframe vibration control and rotor blade damping. The main advantages to using F2MC tubes over conventional hydraulic devices with pistons are their high strain-induced pumping capability and high force output per unit pressure.A laboratory-scale rotorcraft tailboom was used as a testbed for demonstrating new F2MC vibration absorber concepts. The tailboom is modeled using Euler-Bernoulli beam finite elements and coupled to a model of the F2MC tubes and fluidic circuit. Based on the combined structural and fluid system model, an F2MC damped vibration absorber was designed and built using four F2MC tubes placed near the corners of the rectangular tailboom. Experimental results showed reduction of both lateral and torsional vibrations in a 26.7 Hz coupled tailboom vibration mode by up to 80%. Three fluidic circuits were tested for performance and model verification. This single-mode F2MC vibration absorber was then modified so that two tailboom vibration modes can be treated by the same device. A lateral absorber frequency was tuned by selecting lengths of short branch segments connecting the left and right F2MC tube pairs. Then, a vertical absorber frequency was tuned by selecting the appropriate length of tubing to connect the top and bottom F2MC tube pairs. The tuned multi-mode vibration absorber reduced vibration by 63% in the vertical mode and 65% in the lateral mode, whereas a comparable absorber designed to only treat the vertical mode reduced vibration by 68% in the vertical mode but only 42% in the lateral mode. The weight penalty from modifying the circuit to treat both modes was only 2% of the original absorber weight.New F2MC devices are proposed to augment the damping of both articulated and hingeless rotor blades. The proposed device for articulated blades dissipates energy by using an F2MC tube to pump fluid through an orifice. In contrast, the proposed device for hingeless blades uses an F2MC tube as part of a damped vibration absorber with a tuned inertia track. Models are derived for both conceptsto assess the feasibility of these dampers for representative articulated, stiff-inplane, and soft-inplane rotor blades. Parametric studies are conducted to understand how fluidic circuit design variables impact damper performance. For the articulated blade damper, increasing orifice resistance increases the damping ratio of the blade-damper system at the cost of increased F2MC tube oscillatory pressures. Increasing the accumulator capacitance reduces the F2MC damper stiffness and also increases the achievable damping, although the benefits diminish as the accumulator becomes larger. A stiff-inplane hingeless blade is modeled with beam finite elements, and F2MC damped absorbers are tuned for the first chordwise bending blade mode.Eigenvalue analysis predicts an increase in the first chordwise blade mode damping ratio from a baseline of 0.02 to a range of 0.059-0.066 with the F2MC damped absorber. Using a large accumulator in the absorber fluidic circuit improves the absorber effectiveness and reduces the inertance required for tuning the fluidic circuit to a specific frequency. Benchtop tests were conducted on a 9.7-foot diameter rotor integrated with a prototype articulated blade F2MC damper. Springs were attached to the blade to simulate centrifugal stiffness, and both frequency-domain and time-domain data were collected to assess damper performance. Model predictions of blade displacement and F2MC tube pressure were verified by experiments. Blade damping ratios in frequency-domain benchtop tests increase from a range of 0.054-0.064 with the orifice fully closed to a range of 0.300-0.335 with the orifice tuned to maximize damping. In time-domain benchtop tests, measured damping ratios increase from 0.062-0.090 with the orifice fully closed to a range of 0.298-0.404 with the orifice tuned. The benchtop tests and model verification are a key first step in developing functional F2MC damper technology for rotor blade applications.

Download or read book The NASA industry Design Analysis Methods for Vibrations DAMVIBS Program A Government Overview written by and published by . This book was released on 1992 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vibration Control of Distributed Parameter Systems and Fluidic Flexible Matrix Composites written by Amir Lotfi Gaskarimahalle and published by . This book was released on 2009 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on with total page 1026 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Aeronautical Engineering written by and published by . This book was released on 1989 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).

Download or read book Aeronautical Engineering A Cumulative Index to a Continuing Bibliography supplement 235 written by and published by . This book was released on 1989 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The History of the XV 15 Tilt Rotor Research Aircraft written by Martin D. Maisel and published by . This book was released on 2000 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Launch vehicle Dynamics written by Harry L. Runyan and published by . This book was released on 1961 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Riveted Lap Joints in Aircraft Fuselage written by Andrzej Skorupa and published by Springer Science & Business Media. This book was released on 2012-06-23 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue of the pressurized fuselages of transport aircraft is a significant problem all builders and users of aircraft have to cope with for reasons associated with assuring a sufficient lifetime and safety, and formulating adequate inspection procedures. These aspects are all addressed in various formal protocols for creating and maintaining airworthiness, including damage tolerance considerations. In most transport aircraft, fatigue occurs in lap joints, sometimes leading to circumstances that threaten safety in critical ways. The problem of fatigue of lap joints has been considerably enlarged by the goal of extending aircraft lifetimes. Fatigue of riveted lap joints between aluminium alloy sheets, typical of the pressurized aircraft fuselage, is the major topic of the present book. The richly illustrated and well-structured chapters treat subjects such as: structural design solutions and loading conditions for fuselage skin joints; relevance of laboratory test results for simple lap joint specimens to riveted joints in a real structure; effect of various production and design related variables on the riveted joint fatigue behaviour; analytical and experimental results on load transmission in mechanically fastened lap joints; theoretical and experimental analysis of secondary bending and its implications for riveted joint fatigue performance; nucleation and shape development of fatigue cracks in riveted longitudinal lap joints; overview of experimental investigations into the multi-site damage for full scale fuselage panels and riveted lap joint specimens; fatigue crack growth and fatigue life prediction methodology for riveted lap joints; residual strength predictions for riveted lap joints in a fuselage structure. The major issues of each chapter are recapitulated in the last section.

Download or read book Composite Materials for Aircraft Structures written by Alan A. Baker and published by AIAA. This book was released on 2004 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Aerodynamic Simulation written by and published by . This book was released on 1987 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Automatic Flight Control written by Pallet and published by John Wiley & Sons. This book was released on 1987 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an updated edition of the well-known introduction to the principles involved in the automatic flight of fixed-wing and rotary wing aircraft. The principles are related to the systems used in the representative types of aircraft (UK and US) currently in service.

Download or read book Unsteady Computational Fluid Dynamics in Aeronautics written by P.G. Tucker and published by Springer Science & Business Media. This book was released on 2013-08-30 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and turbulence and its modelling (LES, RANS, transition, VLES, URANS). The volume concludes by pointing forward to future horizons and in particular the industrial use of LES. The writing style is accessible and useful to both academics and industrial practitioners. From the reviews: "Tucker's volume provides a very welcome, concise discussion of current capabilities for simulating and modellng unsteady aerodynamic flows. It covers the various pos sible numerical techniques in good, clear detail and presents a very wide range of practical applications; beautifully illustrated in many cases. This book thus provides a valuable text for practicing engineers, a rich source of background information for students and those new to this area of Research & Development, and an excellent state-of-the-art review for others. A great achievement." Mark Savill FHEA, FRAeS, C.Eng, Professor of Computational Aerodynamics Design & Head of Power & Propulsion Sciences, Department of Power & Propulsion, School of Engineering, Cranfield University, Bedfordshire, U.K. "This is a very useful book with a wide coverage of many aspects in unsteady aerodynamics method development and applications for internal and external flows." L. He, Rolls-Royce/RAEng Chair of Computational Aerothermal Engineering, Oxford University, U.K. "This comprehensive book ranges from classical concepts in both numerical methods and turbulence modelling approaches for the beginner to latest state-of-the-art for the advanced practitioner and constitutes an extremely valuable contribution to the specific Computational Fluid Dynamics literature in Aeronautics. Student and expert alike will benefit greatly by reading it from cover to cover." Sébastien Deck, Onera, Meudon, France

Download or read book Computational Fluid and Solid Mechanics 2003 written by K.J Bathe and published by Elsevier. This book was released on 2003-06-02 with total page 2485 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bringing together the world's leading researchers and practitioners of computational mechanics, these new volumes meet and build on the eight key challenges for research and development in computational mechanics. Researchers have recently identified eight critical research tasks facing the field of computational mechanics. These tasks have come about because it appears possible to reach a new level of mathematical modelling and numerical solution that will lead to a much deeper understanding of nature and to great improvements in engineering design.The eight tasks are: The automatic solution of mathematical models Effective numerical schemes for fluid flows The development of an effective mesh-free numerical solution method The development of numerical procedures for multiphysics problems The development of numerical procedures for multiscale problems The modelling of uncertainties The analysis of complete life cycles of systems Education - teaching sound engineering and scientific judgement Readers of Computational Fluid and Solid Mechanics 2003 will be able to apply the combined experience of many of the world's leading researchers to their own research needs. Those in academic environments will gain a better insight into the needs and constraints of the industries they are involved with; those in industry will gain a competitive advantage by gaining insight into the cutting edge research being carried out by colleagues in academia. Features Bridges the gap between academic researchers and practitioners in industry Outlines the eight main challenges facing Research and Design in Computational mechanics and offers new insights into the shifting the research agenda Provides a vision of how strong, basic and exciting education at university can be harmonized with life-long learning to obtain maximum value from the new powerful tools of analysis

Download or read book The Standard Handbook for Aeronautical and Astronautical Engineers written by Mark Davies and published by . This book was released on 2003 with total page 1880 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designed as a one-stop reference for engineers of all disciplines in aeronautical and aerospace engineering, this handbook seeks to filter mechanical engineering applications to specifically address aircraft and spacecraft science and military engineering.

Download or read book ICRRM 2019 System Reliability Quality Control Safety Maintenance and Management written by Vinit Kumar Gunjan and published by Springer. This book was released on 2019-06-13 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Content of this proceedings discusses emerging trends in structural reliability, safety and disaster management, covering topics like total quality management, risk maintenance and design for reliability. Some papers also address chemical process reliability, reliability analysis and engineering applications in chemical process equipment systems and includes a chapter on reliability evaluation models of chemical systems. Accepted papers from 2019 International Conference on Reliability, Risk Maintenance and Engineering Management (ICRRM 2019) are part of this conference proceeding. It offers useful insights to road safety engineers, disaster management professionals involved in product design and probabilistic methods in manufacturing systems.