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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modeling and implementation of plates with enhanced active constrained layer damping.

January 2004 (has links)
by Dai Ruoli. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 85-88). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 摘要 --- p.ii / ACKNOWLEDGEMENTS --- p.iii / TABLE OF CONTENTS --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.ix / Chapter CHAPTER ONE - --- BACKGROUND AND LITERATURE REVIEW --- p.1 / Chapter 1.1 --- Piezoelectric Materials --- p.2 / Chapter 1.2 --- Literature Review on Vibration Control --- p.6 / Chapter 1.2.1 --- Passive control (PCL treatment) --- p.6 / Chapter 1.2.2 --- Active control (PA treatment) --- p.7 / Chapter 1.2.3 --- Active passive hybrid control (ACL and EACL treatment) --- p.8 / Chapter 1.3 --- Finite Element Method --- p.11 / Chapter 1.4 --- Positive Position Feedback Control --- p.12 / Chapter 1.5 --- Damping --- p.13 / Chapter 1.5.1 --- GHM method --- p.13 / Chapter 1.5.2 --- Rayleigh damping --- p.13 / Chapter 1.6 --- Thesis Objectives and Outline --- p.15 / Chapter CHAPTER TWO - --- SYSTEM MODELING --- p.16 / Chapter 2.1 --- Assumptions --- p.17 / Chapter 2.2 --- Elements --- p.18 / Chapter 2.3 --- FEM Matrices --- p.22 / Chapter 2.3.1 --- Element matrices component related to in-plane displacement --- p.22 / Chapter 2.3.2 --- Element matrices component related to bending displacement --- p.30 / Chapter 2.3.3 --- Element matrices component related to shear strain --- p.35 / Chapter 2.3.4 --- Overall element matrices --- p.38 / Chapter 2.3.5 --- Piezoelectric control forces --- p.39 / Chapter 2.4 --- Damping --- p.40 / Chapter 2.4.1 --- Damping due to the viscoelastic materials --- p.40 / Chapter 2.4.2 --- Inherent structural damping --- p.43 / Chapter 2.5 --- Edge Elements --- p.44 / Chapter 2.6 --- Model Reduction --- p.46 / Chapter CHAPTER THREE - M --- ODEL VALIDATION --- p.47 / Chapter 3.1 --- Beam with Passive ACL Damping Treatment --- p.48 / Chapter 3.2 --- Clamped-Clamped Plate with Fully Covered ACL --- p.50 / Chapter 3.3 --- Cantilever Plate with ACL/EACL Patch --- p.52 / Chapter CHAPTER FOUR - --- STUDIES ON EACL PATCH LOCATION --- p.57 / Chapter 4.1 --- Overview of the Numerical Examples --- p.58 / Chapter 4.2 --- Patch Location on Passive Damping Ability --- p.61 / Chapter 4.3 --- Patch Location on Actuating Ability --- p.65 / Chapter 4.4 --- Discussion on Patch Location --- p.69 / Chapter CHAPTER FIVE - --- SYSTEM IMPLEMENTATION --- p.71 / Chapter 5.1 --- Experimental Setup --- p.71 / Chapter 5.1.1 --- Open loop test --- p.72 / Chapter 5.1.2 --- Closed loop test --- p.72 / Chapter 5.2 --- Controller Design --- p.74 / Chapter 5.3 --- Results and Discussion --- p.76 / Chapter CHAPTER SIX - --- CONCLUSION AND FUTURE WORK --- p.81 / Chapter 6.1 --- Summary and Conclusion --- p.81 / Chapter 6.2 --- Recommendations for Future Research --- p.82 / "APPENDIX - PZT data sheet from PIEZO SYSTEMS, INC" --- p.83 / BIBLIOGRAPHY --- p.85
2

Design and analysis of a damped escapement mechanism

Gada, Kantilal Nanji 12 1900 (has links)
No description available.
3

A study of system damping

Schwantes, Stanley Norman. January 1963 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 96).
4

Evaluation of analytical and experimental methods to predict constrained layer damping behavior /

Schultze, John Francis, January 1992 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 116-118). Also available via the Internet.
5

Damping in stiffener welded structures

Ehnes, Charles W. 06 1900 (has links)
Approved for public release, distribution is unlimited / Damping of welded structures is a subject of great interest and application for the navy as relates to ship shock survivability and acoustic transmission of ship noise. The purpose of this research is to study the effects of welding on damping. A generic model of a warship's hull structure was used to study damping effects. The model's natural frequencies and mode shapes were calculated using a finite element model prior to model testing. The frequency response and natural frequencies of the model were determined experimentally by exciting the model and measuring the response throughout the structure using Frequency Response Functions (FRF's). The results were compared with the finite element modeling. The damping ratio of the model in relation to position from excitation was calculated using the half-power point method and then a more detailed analysis of frequency dependent damping versus position was made using modal parameter extraction using the Complex Exponential Method. / Lieutenant, United States Navy
6

Self-powered, self-sensing magnetorheological dampers. / CUHK electronic theses & dissertations collection

January 2012 (has links)
磁流變阻尼器可用於各種動態系統的半主動振動控制,非常有前景。在當前的磁流變阻尼器系統中,需要使用外加并分離的電源和動態傳感器。本論文提出并探索了自供能自傳感磁流變阻尼器。它將能源採集、動態傳感和磁流變阻尼三種技術集成到同一器件中,具有內置的發電機制,和速度/位移傳感能力。此多功能的集成可以對當前的磁流變阻尼器系統帶來眾多的益處,如更節能、更高的可靠性、尺寸及重量的減少、較低的成本、以及更少的維護需求。該研究成果可以促進各種動態系統,如懸架系統和義肢的發展。 / 在論文中,作者對自供能自傳感磁流變阻尼器的概念、原理、設計方法、設計難點及解決方案進行了探討,設計製作了兩件原型,並對原型進行了性能測試。作者提出并探索了幾種可與磁流變阻尼器集成的發電機制,和動態傳感的方法。對發電、動態傳感和阻尼力三種性能,進行了建模、理論分析、以及實驗驗證。作者提出并驗證了自供能自傳感磁流變阻尼器的數學模型,該模型考慮了單獨的功能以及多功能間的相互作用。本論文對自供能磁流變阻尼器系統進行了探討分析,包括能源產生與磁流變阻尼的相互作用、自供能判據、工作範圍和設計指引。還提出并探索了一個自供能控制器,以及一種複合的磁場隔離方法。 / Magnetorheological (MR) dampers are promising for semi-active vibration control of various dynamic systems. In the current MR damper system, separate power supply and dynamic sensor are required. This research is aimed to propose and investigate self-powered, self-sensing (SPSS) MR dampers, which integrate energy harvesting, sensing and MR damping technologies into one device. SPSS MR damper has self-contained power generation and velocity/displacement sensing capabilities. This multifunctional integration will bring great benefits such as energy saving, higher reliability, size and weight reduction, lower cost, and less maintenance for the use of MR damper systems. It will advance the technology of various dynamic systems such as suspensions and prostheses. / Concepts, principles, design methodology, key issues and solutions of SPSS MR dampers are studied. Two prototypes of the SPSS MR dampers are designed, fabricated, and tested. Several integrated power generation and sensing methods for MR dampers are proposed and investigated. Modeling, theoretical analyses, and experimental studies on power generation ability, sensing capability and damping force performances are conducted. Models of SPSS MR dampers considering individual functions and interactions are developed and validated experimentally. Systematic studies on the self-powered MR damper system are performed, including interaction between the power generation and MR damping, self-powered criterion, working range and design guidelines. Moreover, a self-powered controller and combined magnetic-field isolation method are proposed and investigated. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chen, Chao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 163-172). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / ABSTRACT --- p.i / 摘要 --- p.iii / TABLE OF CONTENTS --- p.vii / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.xvii / Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background and Motivation --- p.2 / Chapter 1.1.1 --- MR fluids --- p.2 / Chapter 1.1.2 --- MR dampers --- p.3 / Chapter 1.1.3 --- Previous research on functional integration of MR dampers --- p.7 / Chapter 1.2 --- Research Objective --- p.10 / Chapter 1.3 --- Thesis Organization --- p.12 / Chapter 2 --- DESIGN OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.13 / Chapter 2.1 --- Concept and Key Issues of Multifunctional Integration --- p.14 / Chapter 2.2 --- Configurations of Different Methods of Multiple Functions --- p.17 / Chapter 2.3 --- Principles of SPSS MR Dampers --- p.18 / Chapter 2.3.1 --- Structure and operation principle of the first prototype --- p.18 / Chapter 2.3.2 --- Structure and operation principle of the second prototype --- p.21 / Chapter 2.3.3 --- Energy flow of SPSS MR damper --- p.25 / Chapter 2.4 --- Materials Used in Design --- p.27 / Chapter 2.5 --- Fabrication of Prototypes --- p.32 / Chapter 2.6 --- Experimental Setup --- p.35 / Chapter 2.7 --- Chapter Summary --- p.37 / Chapter 3 --- POWER GENERATION OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.39 / Chapter 3.1 --- Introduction to Electromagnetic Energy Harvesting --- p.40 / Chapter 3.2 --- Finite Element Method --- p.42 / Chapter 3.3 --- Slotted Power Generation Method --- p.44 / Chapter 3.3.1 --- Modeling and analysis of slotted power generation --- p.44 / Chapter 3.3.2 --- Experimental results of slotted power generation --- p.52 / Chapter 3.4 --- Slotless Power Generation Method --- p.56 / Chapter 3.4.1 --- Design considerations --- p.56 / Chapter 3.4.2 --- Modeling and analysis of slotless power generation --- p.57 / Chapter 3.4.3 --- Experimental results of slotless power generation --- p.62 / Chapter 3.5 --- Frequency Multiplication Effect of Generated Voltage --- p.65 / Chapter 3.6 --- Chapter Summary --- p.67 / Chapter 4 --- SENSING OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.69 / Chapter 4.1 --- Introduction to Self-sensing Ability --- p.70 / Chapter 4.1.1 --- Self-sensing for vibration control --- p.70 / Chapter 4.1.2 --- Self-sensing of SPSS MR damper --- p.71 / Chapter 4.2 --- Moving-spacer Velocity Sensing Method --- p.73 / Chapter 4.3 --- Velocity-extraction Method from Slotted Power Generator --- p.80 / Chapter 4.4 --- Velocity-extraction Method from Slotless Power Generator --- p.86 / Chapter 4.5 --- Chapter Summary --- p.90 / Chapter 5 --- DAMPING FORCE OF SELF-POWERED, SELF-SENSING MR DAMPERS --- p.93 / Chapter 5.1 --- Design of MR Damping Part --- p.94 / Chapter 5.2 --- Testing Results of MR Damping Force of the First Prototype --- p.97 / Chapter 5.3 --- Testing Results of Damping Force of the Improved Prototype --- p.101 / Chapter 5.4 --- Damping Force Modeling and Identification --- p.105 / Chapter 5.5 --- Chapter Summary --- p.110 / Chapter 6 --- INTERACTION ANALYSIS --- p.111 / Chapter 6.1 --- Modeling Summary and Magnetic Field Interactions of SPSS MRD --- p.112 / Chapter 6.1.1 --- Modeling summary of SPSS MR dampers --- p.112 / Chapter 6.1.2 --- Magnetic field interactions --- p.114 / Chapter 6.2 --- Analysis of a Versatile Self-powered MR Damper System --- p.122 / Chapter 6.3 --- Application to Vehicle Suspension Systems --- p.130 / Chapter 6.3.1 --- Modeling of suspension system --- p.131 / Chapter 6.3.2 --- Working range and vibration control efficiency under on-off controller --- p.133 / Chapter 6.4 --- Design Guidelines of Self-powered Working Range --- p.141 / Chapter 6.5 --- A Proposed Self-powered Controller --- p.146 / Chapter 6.6 --- Chapter Summary --- p.153 / Chapter 7 --- CONCLUSION AND FUTURE WORK --- p.155 / Chapter 7.1 --- Conclusion --- p.155 / Chapter 7.2 --- Future Work --- p.160 / Chapter 8 --- BIBLIOGRAPHY --- p.163 / Chapter 9 --- APPENDIX --- p.173 / Chapter A. --- MR Fluid Datasheet --- p.173 / Chapter B. --- Sectional Views of Prototypes --- p.175
7

Design of an adaptive dynamic vibration absorber

Ting-Kong, Christopher. January 2001 (has links)
Bibliography: leaves 94-97. Electronic publication; full text available in PDF format; abstract in HTML format. Electronic reproduction.[Australia] :Australian Digital Theses Program,2001.
8

Active isolation of machinery vibration from flexible structures

Howard, Carl Q. January 1999 (has links)
Vibrating machinery must be isolated from a supporting structure if the vibration is likely to cause fatigue of components or annoyance to people due to direct vibration exposure or from the noise radiated by the vibrating structure. Active vibration isolation can be applied in these situations to extend the low frequency performance of passive vibration isolators. In this thesis, theoretical and experimental investigations are described for a vibrating rigid body that is passively and actively isolated from a beam and a cylinder, respectively. The focus of the work is to investigate the vibrational power transmitted by translational forces and rotational moments into the support structure. For the investigation of the simply supported beam, a classical mathematical model is examined and finite element modelling is used to predict the power transmission into the beam when active vibration control is used. The results show that power transmission by moments is significant and cannot be ignored when the vibrational power transmission into the support structure is actively controlled. To control the power transmission by translational forces and rotational moments, a novel six axis active vibration isolator and a novel six axis force transducer were constructed to be used in the experimental investigations. Using vibrational power transmission as a cost function to be minimized in active control experiments presents unique problems because negative values of translational power transmission are possible when power transmission from rotational moments is ignored or when phase errors occur in the transducer outputs. Active control attempts which converge the cost function to a negative value of power transmission along a particular axis can result in overall vibration levels in the structure which are greater than without active control. To prevent the increase in vibration levels, minimization of the squared value of power transmission is investigated as a potential cost function. A method is described to combine force and velocity signals into a signal which is proportional to the vibrational power transmission and is suitable for use with an existing filtered-x Least Mean Squares controller, so that the squared vibrational power transmission can be minimized. Experimental trials were performed to actively minimize the power transmission into a simply supported beam from a vibrating rigid body using a single axis and a six axis active vibration isolator. The purpose of the experimental work was to confirm the theoretical findings and to find a practical method to measure power transmitted by rotational moments. The vibrational power transmission from a vibrating rigid body that is passively and actively isolated from a cylinder was also investigated. The theoretical model of the cylinder was similar to the beam model, although the dynamics of the cylinder makes the solution more complicated. Two experimental trials were conducted to verify the theoretical model and involved the use of the single axis and the six axis active vibration isolators, respectively. / Thesis (Ph.D.)--School of Mechanical Engineering, 1999.
9

Effect of drying on damping and stiffness of nailed joints between wood and plywood /

Zhou, Jun, January 1984 (has links)
Thesis (M.S.)--Oregon State University, 1985. / Typescript (photocopy). Includes bibliographical references (leaves 81-82). Also available on the World Wide Web.
10

Some fundamental issues of constrained layer damping treatments /

Huang, Yao-Hsin. January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 77-80).

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