DOCSLIB.ORG

Tribology in Industry a Historical Review of Gas Lubrication

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Tribology in Industry a Historical Review of Gas Lubrication Vol. 40, No. 2 (2018), 165-182, DOI: 10.24874/ti.2018.40.02.01 Tribology in Industry www.tribology.rs VIEW RE A Historical Review of Gas Lubrication: From Reynolds to Active Compensations L. Lentini a, M. Moradi a, F. Colombo a a Department of Mechanical and Aerospace Engineering, Politecnico di Torino Corso Duca Degli Abruzzi 24, 10129, Turin, Italy. Keywords: A B S T R A C T Historical review Friction and wear are tribological phenomena that have produced Gas lubrication significant economic damage and environmental issues throughout our Aerostatic bearing history. Different kinds of lubricants and coatings have been employed in Active compensation the attempt of reducing friction losses. Because of their remarkable Passive compensation performance, gas lubricated systems are characterized by almost zero friction and wear. For this reason, they can be utilized in applications Corresponding author: where rolling and fluid bearings cannot, e.g., metrology, medical Luigi Lentini equipment and tool machine. This paper reviews the evolution of gas Department of Mechanical and lubrication through history. The topography of the subject is described Aerospace Engineering, Politecnico from its origins to how it was shaped over the centuries, trying to preserve di Torino, Corso Duca Degli Abruzzi the logical cause and effect relationship of the events. For the sake of 24, 10129, Turin, Italy. consistency, the review considers only the key past contributions which are E-mail: [email protected] strictly related to gas lubrication. © 2018 Published by Faculty of Engineering 1. INTRODUCTION performance, gas lubricants make it possible to significantly reduce friction and wear, thus Friction and wear are tribological phenomena providing systems with high positional that have produced significant economic accuracy and low environmental impact. For damage and environmental issues throughout this reason, gas lubricated systems are our history. The mechanical and thermal employed for high-precision applications, such severities caused by friction along with the as medical equipment and measuring and tool consequent wear are some of the most relevant machines [1,2]. problems faced by engineers in machine design. It is suffice to say that one-third of the fuel This paper reviews the history of gas consumption of passenger cars is used to lubrication. The topography of the subject is compensate frictional losses. Different kinds of described from its origins to how it was shaped lubricants and coatings are a solution currently over the centuries, trying to preserve the adopted to reduce friction and avoid the logical cause and effect relationship of the presence of wear. Because of their remarkable events. For the sake of consistency, the review 165 L. Lentini et al., Tribology in Industry Vol. 40, No. 2 (2018) 165-182 considers only the key past contributions which 1884) during his studying on the fluid flow are strictly related to gas lubrication. within brass tubes. The first part of the paper deals with the most In the same period, Claude Louis Navier (1785- important studies in fluid mechanics, i.e., the 1836) along with Sir George Gabriel Stokes took equation of motion and the equation of advantage of Euler and Poiseuille’s contributions continuity, which made it possible to lay the to provide one of the milestones of fluid foundations of lubrication theory. Secondly, the mechanics: Navier-Stokes Equations. paper describes the first experiments and 퐷푢 휕푃 휕2푢 휕2푢 휕2푢 theories on hydrodynamic lubrication and 휌 = 휌푋 − + 휇 ( 2 + 2 + 2 ) lubricant properties. The review continues by 퐷푡 휕푥 휕푥 휕푦 휕푧 focusing on the historical evolution of gas 2 2 2 퐷푣 휕푃 휕 푣 휕 푣 휕 푣 (2) lubrication up to today. 휌 = 휌푌 − + 휇 ( + + ) 퐷푡 휕푦 휕푥2 휕푦2 휕푧2 퐷푤 휕푃 휕2푤 휕2푤 휕2푤 휌 = 휌푍 − + 휇 ( + + ) 2. THE BEGINNING: THE BIRTH OF FLUID { 퐷푡 휕푧 휕푥2 휕푦2 휕푧2 MECHANICS This set of equations made it possible to model Although Daniel Bernoulli (1700-1782) was the the motion of viscous fluids by considering the first to publish a book in the field of fluid equilibrium between volume (inertial, mechanics: Hydrodynamica, sive De viribus et gravitational), pressure and viscous forces. motibus fluidorum commentarii, it is commonly recognised that the Swiss engineer Leonhard Euler (1707-1783) was the founder of the 3. FOUNDATION OF THE LUBRICATION subject. Driven by his passion for mathematics, THEORY: FROM EXPERIMENTS TO Euler was one of the most eminent scientists in REYNOLDS’ EQUATION history who provided the Equation of continuity and the Equations of motion for non-viscous Performing experimental studies on lubricant flows. This mathematical framework was the properties was the consequential and natural first step in laying the foundations of fluid film step of the development of the theoretical lubrication theory. The next step towards the framework by Navier and Stokes. Gustave formulation of the lubrication theory was Adolphe Hirn (1815-1890) was the first who provided by the French physician Jean Léonard investigated the frictional properties of different Marie Poiseuille (1799-1869), who analysed the kinds of fluids. He pioneered experimental properties of viscous fluids. He spent most of his works on fluid bearings by testing twelve life performing experimental investigations on natural oils (both mineral and fatty oils), air and blood flow in human capillaries. The result of water as lubricants. To perform these these arduous experiments was a formula to experiments, he developed a fine friction study viscous fluid flowing under laminar balance (Fig.1). regimes (Equation 1). According to Fig. 1, this friction balance consists 128 휇퐿푄 (1) of a half bronze bearing loaded against a Δ푃 = 4 휋푑 polished cylindrical cast iron drum. The bearing This equation made it possible to assess the supports a shaft that can rotate at different pressure drop within laminar flow through thin speeds and which is loaded with two dead pipes. He found that the pressure drop Δ푃 along weights applied at the extremities of two a straight capillary increases proportionally to horizontal lever arm of the same length. Given a the tube length 퐿, the fluid mass flow rate 푄 and constant rotational speed, frictional forces were viscosity 휇, and it decreases with the fourth measured by adding weights to balance the power of the conduit diameter 푑. Today, this misalignments between the two lever arms formula is known as Hagen-Poiseuille’s law since induced by friction. Performing these the same results were independently and experiments allowed Hirn to discover the contemporarily achieved by the German existence of the “frottement médiat” and the engineer Gotthilf Heinrich Ludwig Hagen (1797- “frottement immediate” regimes. 166 L. Lentini et al., Tribology in Industry Vol. 40, No. 2 (2018) 165-182 proportional to the speed, whereas, in the presence of high loads it varies approximately according to the square root of the speed. In addition, Hirn argued that also the temperature of the lubricant may have an important role. He noted that when the system worked for a long time, friction increased the lubricant temperature and consequently induced unbalances between the torque arms. According to this, he installed a water-cooled system CC’ (Fig. 1) that made it possible to keep the bearing temperature constant within plus or minus 0.1 °C, and unaware of Joule’s experiments, he also provided necessary measurements to change the water temperature by 1°C (3630 J with respect to the correct value measured by Joule 4090 J [4]). In 1879, Hirn’s studies were refined by Robert Henry Thurston (1839-1903). Thurston showed that, giving an increasing speed, the friction coefficient within a fluid bearing initially decreases below its static value, and reaches its minimum and then increases to a constant value. He also noted that the value of the minimum friction coefficient varied together with the applied load. Hirn and Thurston’s research was efficiently exploited by the Russian engineer Nikolay Pavlovitch Petroff (1836-1920). Petroff laid the Fig. 1. Hirn’s experimental apparatus for frictional foundation of the hydrodynamic theory of measurements. friction and carried out further viscosity measurements with the aid of an experimental He observed that the “frottement médiat” occurs apparatus similar to the one employed by when a full fluid film separates the surfaces in Poiseuille. His most important contribution was the presence of relative motions, i.e., providing the first analytical formulation to hydrodynamic regimes, whereas the “frottement evaluate friction coefficients in the presence of immediate” takes place in dry interactions or hydrodynamic lubrication. Petroff’s formula when the fluid film lubricant is broken. correlates the friction force and bearing parameters: “For water and air to act as lubricant it is 휇푈퐴 necessary for the drum to turn sufficiently rapidly 퐹푣 = 휇 휇 (3) to drag them into the bearing. When the speed 휀 + + 휆1 휆2 reduces to a certain value, the two non-viscous fluids are expelled by the pressure and the where, 휀 and 휇 are the film thickness and surfaces come into direct contact, and friction at viscosity of the lubricant, 푈 is the tangential once becomes enormous [3]” relative velocity between the interacting surfaces and 퐴 is the contact area. The By experimenting with different operating coefficients 휆1 and 휆2 consider slip phenomena conditions and lubricants, Hirn discovered that at walls of the interacting surfaces. Despite much under the hydrodynamic regime, friction effort devoted to performing studies on coefficients depend on the rotational speed, load hydrodynamic lubrication, Petroff was not able and lubricant properties. In the presence of full to find the relation that exists between friction film lubrication and light loads, friction is and the load carrying capacity of a fluid bearing. 167 L. Lentini et al., Tribology in Industry Vol. 40, No. 2 (2018) 165-182 The first scientist who explained a principle that endows fluid bearings with their load carrying capacity was Beauchamp Tower (1845-1904) in 1883-1884.
Load more

Recommended publications
  • Rationalizing the Triboelectric Series of Polymers
    Communication Cite This: Chem. Mater. 2019, 31, 1473−1478 pubs.acs.org/cm Rationalizing the Triboelectric Series of Polymers Xuan Zhang, Linfeng Chen, Yan Jiang, Weichun Lim, and Siowling Soh* Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore *S Supporting Information ontact electrification is the phenomenon in which static electronic components (e.g., “tribotronics”),13,14 filtration,15,16 C charge is generated when two materials come into and sensors.17,18 Therefore, there is a great need to select the contact and are then separated. After contact, one material appropriate types of materials for useful applications related to charges positively and the other charges negatively (Figure 1). contact electrification or for the fabrication of noncharging This phenomenon is ubiquitous: almost all types of materials surfaces for circumstances in which contact electrification is 1,3,19,20 (e.g., metal, semiconductor, inorganic materials, and polymers) undesirable. charge upon contact. Hence, contact electrification has a vast The triboelectric series is widely used by researchers and range of influences in our lives.1 In many of our daily activities, engineers for the selection of materials for applications related fi we frequently encounter slight annoyances as a result of static to contact electri cation. It ranks a list of materials according charge (e.g., the adherence of dust particles on charged to their tendency to charge positively or negatively (Figure 1). surfaces and the sticking of clothes after drying). The A material that is ranked more positively than a contacting phenomenon is also problematic for many types of industries material charges positively while the contacting material (e.g., petrochemical, chemical, pharmaceutical, semiconductor, charges negatively, and vice versa.
    [Show full text]
  • Lubricant Evaluation for Bearing Operation in Rotating Electric Machines
    TECHNICAL NOTES Lubricant evaluation for bearing operation in rotating electric machines Gabriel Chagas Storti Aleksander Kokot WEG - Energy WEG - Motors Brazil Brazil [email protected] [email protected] Abstract - Poor lubrication is one major cause of bearing failures, including bearings for electric machines. This paper describes good practices for lubricant specification in order to maximize bearing life beyond the calculated expectation. Some factors can determine the choice of the most suitable lubricant for each bearing and its application. 1 INTRODUCTION A rotating electric machine has a rotor, in which there is a laminated core mounted onto the shaft. The bearings are intended to allow the rotation of the rotor within a thin air gap between it and the stator, and with a minimized friction, by connecting the dynamic portion into the static. Considering the particularities of electric machines, such as mounting positions, rotation speed, shaft diameters, different radial and axial loads, it is possible to understand the reason for many Figure 1: Hydrodynamic lubrication of plane-slider. bearings types and different lubricants, as for their Figure adapted from the book "Bearing Design in purpose or even the lubrication method. Machinery - Engineering Tribology and Lubrication" [2] This paper considers the main bearings types used by WEG, which are hydrodynamic and rolling- For hydrodynamic lubrication, the viscosity "µ" is elements bearings. Hydrodynamic bearings are oil the most important characteristic of a fluid because lubricated, and the rolling bearings (anti-friction the bearing load capacity is proportional to oil bearings) can be oil or grease lubricated. viscosity during the desired rotations. Proper lubrication is important to avoid premature Viscosity is sensitive to changes in temperature.
    [Show full text]
  • Dynamic Performance and Design Aspects of Compliant Fluid Film Bearings
    KTH Industrial Engineering and Management DYNAMIC PERFORMANCE AND DESIGN ASPECTS OF COMPLIANT FLUID FILM BEARINGS Matthew Y.J Cha KTH Royal Institute of Technology School of Industrial Engineering and Management Department of Machine Design Cover figure : Waukesha Bearings Combined Thrust and Journal Bearing Assembly: Solid Polymer Tilting Pad Thrust Bearing with Polymer Lined Tilting Pad Journal Bearing TRITA – MMK 2014:13 ISSN 1400-1179 ISRN/KTH/MMK/R-14/13-SE ISBN 978-91-7595-398-4 Dynamic Performance and Design Aspects of Compliant Fluid Film Bearings Academic thesis, which with the approval of Kungliga Tekniska Högskolan, will be presented for public review in fulfillment of the requirements for a Doctorate of Engineering in Machine Design. Public review: Kungliga Tekniska Högskolan, Gladan, Brinellvägen 83, Stockholm, on April 22, 2015 Printed in Sweden Universitetsservice US-AB PREFACE I am very thankful to Lord Jesus Christ. This work is dedicated for the Glory of God. I give my deepest gratitude to my wife, Woori. She has given me a big support and love. And she waited patiently for me to complete my thesis and taking care of our two lovely children. I would also like to thank my children, Ye-Eun and Ye-Lang for growing up healthy and bringing joy to my family. I want to thank both of my parents and families in Canada for their care, love and support. I would like to thank my supervisor, Professor Sergei Glavatskih for giving me an opportunity to study and research under his guidance. He has brought me into the field of fluid film bearings and there are many things to learn and absorb from his expertise.
    [Show full text]
  • Intrinsically Stretchable Organic-Tribotronic-Transistor for Tactile Sensing
    AAAS Research Volume 2020, Article ID 1398903, 10 pages https://doi.org/10.34133/2020/1398903 Research Article Intrinsically Stretchable Organic-Tribotronic-Transistor for Tactile Sensing Junqing Zhao ,1,2 Tianzhao Bu ,1,2 Xiaohan Zhang,1,2 Yaokun Pang,1,2 Wenjian Li,1,2 Zhi Zhang,1,2 Guoxu Liu,1,2 Zhong Lin Wang,1,2,3 and Chi Zhang 1,2,4 1CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China 2School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China 3School of Material Science and Engineering Georgia Institute of Technology, Atlanta, GA 30332, USA 4Center on Nanoenergy Research, School of Physical Science and Technology, Guangxi University, Nanning 530004, China Correspondence should be addressed to Chi Zhang; [email protected] Received 8 April 2020; Accepted 25 May 2020; Published 24 June 2020 Copyright © 2020 Junqing Zhao et al. Exclusive Licensee Science and Technology Review Publishing House. Distributed under a Creative Commons Attribution License (CC BY 4.0). Stretchable electronics are of great significance for the development of the next-generation smart interactive systems. Here, we propose an intrinsically stretchable organic tribotronic transistor (SOTT) without a top gate electrode, which is composed of a stretchable substrate, silver nanowire electrodes, semiconductor blends, and a nonpolar elastomer dielectric. The drain-source current of the SOTT can be modulated by external contact electrification with the dielectric layer. Under 0-50% stretching both parallel and perpendicular to the channel directions, the SOTT retains great output performance.
    [Show full text]
  • Journal of Advanced Mechanical Design, Systems, and Manufacturing JSME, Vol
    Journal of Advanced Mechanical Design, Vol. 4, No. 1, 2010 Systems, and Manufacturing Optimum Design of Thrust Air Bearing for Hard Disk Drive Spindle Motor* Mohd Danial IBRAHIM**, Tadashi NAMBA**, Masayuki OCHIAI*** and Hiromu HASHIMOTO*** **Graduate School of Science and Engineering, Tokai University 1117, Kitakaname, Hiratsuka City, Kanagawa Prefecture 259-1292, Japan E-mail: [email protected] *** Depatment of Mechanical Engineering, Tokai University 1117, Kitakaname, Hiratsuka City, Kanagawa Prefecture 259-1292, Japan Abstract This paper describes the application of geometry optimization method proposed by Hashimoto to the design of air lubricated thrust bearings used for HDD spindle motors. The optimization is carried out to maximize the dynamic stiffness of air films because the low stiffness is a serious problem of thrust air bearings in the actual application to HDD spindle motor. The optimized dynamic stiffnesses are obtained by changing the allowable film thickness, which is corresponding to the tolerance of bearings. The results obtained show that the optimized thrust air bearings have the comparable stiffness to the oil lubricated thrust bearings and it is verified theoretically that this type of thrust air bearing can be used for HDD spindle motors. Key words: Hard Disk Drive, Spindle Motor, Thrust Air Bearing, Geometrical Optimum Design, Bearing Stiffness 1. Introduction Hard disk drive (HDD) has been playing a big role in the area of informative multimedia as the main storage media for electronics devices. The back bone of these media storage technology actually lies in the revolutionary part of the spindle motor supported mainly by the oil lubricated thrust and journal bearings.
    [Show full text]
  • Rheological Texture in a Journal Bearing with Magnetorheological Fluids
    Delft University of Technology Rheological texture in a journal bearing with magnetorheological fluids Lampaert, Stefan G.E.; Quinci, Federico; van Ostayen, Ron A.J. DOI 10.1016/j.jmmm.2019.166218 Publication date 2020 Document Version Final published version Published in Journal of Magnetism and Magnetic Materials Citation (APA) Lampaert, S. G. E., Quinci, F., & van Ostayen, R. A. J. (2020). Rheological texture in a journal bearing with magnetorheological fluids. Journal of Magnetism and Magnetic Materials, 499, [166218]. https://doi.org/10.1016/j.jmmm.2019.166218 Important note To cite this publication, please use the final published version (if applicable). Please check the document version above. Copyright Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policy Please contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. This work is downloaded from Delft University of Technology. For technical reasons the number of authors shown on this cover page is limited to a maximum of 10. Journal of Magnetism and Magnetic Materials 499 (2020) 166218 Contents lists available at ScienceDirect Journal of Magnetism and Magnetic Materials journal homepage: www.elsevier.com/locate/jmmm Research articles Rheological texture in a journal
    [Show full text]
  • Rationalizing the Triboelectric Series of Polymers
    Communication Cite This: Chem. Mater. 2019, 31, 1473−1478 pubs.acs.org/cm Rationalizing the Triboelectric Series of Polymers Xuan Zhang, Linfeng Chen, Yan Jiang, Weichun Lim, and Siowling Soh* Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore *S Supporting Information ontact electrification is the phenomenon in which static electronic components (e.g., “tribotronics”),13,14 filtration,15,16 C charge is generated when two materials come into and sensors.17,18 Therefore, there is a great need to select the contact and are then separated. After contact, one material appropriate types of materials for useful applications related to charges positively and the other charges negatively (Figure 1). contact electrification or for the fabrication of noncharging This phenomenon is ubiquitous: almost all types of materials surfaces for circumstances in which contact electrification is 1,3,19,20 (e.g., metal, semiconductor, inorganic materials, and polymers) undesirable. charge upon contact. Hence, contact electrification has a vast The triboelectric series is widely used by researchers and range of influences in our lives.1 In many of our daily activities, engineers for the selection of materials for applications related fi we frequently encounter slight annoyances as a result of static to contact electri cation. It ranks a list of materials according charge (e.g., the adherence of dust particles on charged to their tendency to charge positively or negatively (Figure 1). surfaces and the sticking of clothes after drying). The A material that is ranked more positively than a contacting phenomenon is also problematic for many types of industries material charges positively while the contacting material (e.g., petrochemical, chemical, pharmaceutical, semiconductor, charges negatively, and vice versa.
    [Show full text]
  • Software Framework for Tribotronic Systems
    SOFTWARE FRAMEWORK FOR TRIBOTRONIC SYSTEMS APREPRINT Jarno Kansanaho∗ Tommi Kärkkäinen Faculty of Information Technology Faculty of Information Technology University of Jyväskylä, FI-40014, Finland University of Jyväskylä, FI-40014, Finland [email protected] [email protected] October 31, 2019 ABSTRACT Increasing the capabilities of sensors and computer algorithms produces a need for structural support that would solve recurring problems. Autonomous tribotronic systems self-regulate based on feedback acquired from interacting surfaces in relative motion. This paper describes a software framework for tribotronic systems. An example of such an application is a rolling element bearing (REB) installation with a vibration sensor. The presented plug-in framework offers functionalities for vibration data management, feature extraction, fault detection, and remaining useful life (RUL) estimation. The framework was tested using bearing vibration data acquired from NASA’s prognostics data repository, and the evaluation included a run-through from feature extraction to fault detection to remaining useful life estimation. The plug-in implementations are easy to update and new implementations are easily deployable, even in run-time. The proposed software framework improves the performance, efficiency, and reliability of a tribotronic system. In addition, the framework facilitates the evaluation of the configuration complexity of the plug-in implementation. Keywords Software framework · Tribotronic system · Bearing diagnostics · Bearing prognostics · Vibration analysis 1 Introduction The term ’tribology’ was introduced and defined in The Jost Report [1] as "the science and technology of interacting surfaces in relative motion and of the practices related hereto." It was reported that enormous amounts of resources were wasted because mechanical surface phenomena was ignored [2].
    [Show full text]
  • Actively Lubricated Hybrid Journal Bearings Based on Magnetic Fluids
    Actively lubricated hybrid journal bearings based on magnetic fluids for high-precision spindles of machine tools Luis Lopez de Lacalle, Harkaitz Urreta, Gorka Aguirre, Pavel Kuzhir, Luis Norberto López de Lacalle To cite this version: Luis Lopez de Lacalle, Harkaitz Urreta, Gorka Aguirre, Pavel Kuzhir, Luis Norberto López de Lacalle. Actively lubricated hybrid journal bearings based on magnetic fluids for high-precision spindles of machine tools. Journal of Intelligent Material Systems and Structures, SAGE Publications, 2019, 30 (15), pp.2257-2271. 10.1177/1045389X19862358. hal-02426104 HAL Id: hal-02426104 https://hal.archives-ouvertes.fr/hal-02426104 Submitted on 1 Jan 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Page 1 of 53 Journal of Intelligent Material Systems and Structures 1 2 3 4 5 6 7 Actively lubricated hybrid journal 8 9 10 11 bearings based on magnetic fluids for 12 13 14 high precision spindles of machine tools 15 16 17 1 1 2 18 Harkaitz UrretaFor*, Gorka Peer Aguirre Review, Pavel Kuzhir , Luis Norberto 19 20 Lopez de Lacalle 3 21 22 23 24 1 IK4-IDEKO, Arriaga 2, E-20870 Elgoibar, Spain 25 26 27 2 University Côte d’Azur, CNRS UMR 7010 Inst.
    [Show full text]
  • Triboelectric Nanogenerators: Biomechanical Energy Harvesting, Self Powered Sensor and Wearable Applications
    TRIBOELECTRIC NANOGENERATORS: BIOMECHANICAL ENERGY HARVESTING, SELF POWERED SENSOR AND WEARABLE APPLICATIONS A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF BILKENT UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN MATERIALS SCIENCE AND NANOTECHNOLOGY By Ahmet Faruk Yavuz September, 2017 TRIBOELECTRIC NANOGENERATORS: BIOMECHANICAL ENERGY HARVESTING, SELF POWERED SENSOR AND WEARABLE APPLICATIONS By Ahmet Faruk Yavuz September, 2017 We certify that we have read this thesis and that in our opinion it is fully adequate, in scope and in quality, as a dissertation for the degree of Master of Science. Hasan Tarık Baytekin (Advisor) Mehmet Bayındır (Co-Advisor) Şemsettin Türköz Talip Serkan Kasırga Approved for the Graduate School of Engineering and Science: Ezhan Karaşan Director of the Graduate School ii ABSTRACT TRIBOELECTRIC NANOGENERATORS: BIOMECHANICAL ENERGY HARVESTING, SELF POWERED SENSOR AND WEARABLE APPLICATIONS Ahmet Faruk Yavuz M.S. in Materials Science and Nanotechnology Supervisor: Hasan Tarık Baytekin September, 2017 One of the biggest challenges ahead massive advancement of electronic tech- nology is increasing energy consumption. A closer consideration on draining of fossil reserves and rapid development of wearable and portable consumer elec- tronics, inevitable paradigm shift is required towards use of renewable energy sources and self-powered electronic systems respectively. In parallel to this con- sideration, triboelectric nanogenerators have emerged to scavenge
    [Show full text]
  • Investigation of Spherical Bearings for Use in the Ultraform Finishing Polishing Process
    Rochester Institute of Technology RIT Scholar Works Theses 11-24-2014 Investigation of Spherical Bearings for Use in the UltraForm Finishing Polishing Process Randall Scott DeFisher II Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation DeFisher, Randall Scott II, "Investigation of Spherical Bearings for Use in the UltraForm Finishing Polishing Process" (2014). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. R·I·T Investigation of Spherical Bearings for Use in the UltraForm Finishing Polishing Process by Randall Scott DeFisher II A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering Kate Gleason College of Engineering Department of Mechanical Engineering Rochester Institute of Technology November 24, 2014 Committee Approval Investigation of Spherical Bearings for Use in the UltraForm Finishing Polishing Process by Randall Scott DeFisher II Dr. Stephen Boedo Signature: ____________________________ Professor, Thesis Advisor Date: ____________________________ Department of Mechanical Engineering Dr. Agamemnon Crassidis Signature: ____________________________ Associate Professor Date: ____________________________ Department of Mechanical Engineering Dr. Mario Gomes Signature: ____________________________ Assistant Professor Date: ____________________________ Department of Mechanical Engineering Dr. Steven Weinstein Signature: ____________________________ Professor Date: ____________________________ Department of Chemical Engineering Abstract UltraForm Finishing (UFF) is a production-level optical polishing process consisting of a moving belt that is pressed into an optical surface by a carrier wheel. The current configuration is comprised of a cylindrical carrier wheel attached to cylindrical roller bearings.
    [Show full text]
  • Lubrication in MEMS
    9 Lubrication in MEMS Kenneth S. Breuer 9.1 Introduction Brown University Objectives and Outline 9.2 Fundamental Scaling Issues The Cube-Square Law • Applicability of the Continuum Hypothesis • Surface Roughness 9.3 Governing Equations for Lubrication 9.4 Couette-Flow Damping Limit of Molecular Flow 9.5 Squeeze-Film Damping Derivation of Governing Equations • Effects of Vent Holes • Reduced-Order Models for Complex Geometries 9.6 Lubrication in Rotating Devices 9.7 Constraints on MEMS Bearing Geometries Device Aspect Ratio • Minimum Etchable Clearance 9.8 Thrust Bearings 9.9 Journal Bearings Hydrodynamic Operation • Static Journal Bearing Behavior • Journal Bearing Stability • Advanced Journal Bearing Designs • Side Pressurization • Hydrostatic Operation 9.10 Fabrication Issues Cross-Wafer Uniformity • Deep Etch Uniformity • Material Properties 9.11 Tribology and Wear Stiction • The Tribology of Silicon 9.12 Conclusions Acknowledgments 9.1 Introduction As microengineering technology continues to advance, driven by increasingly complex and capable micro- fabrication and materials technologies, the need for greater sophistication in microelectromechanical systems (MEMS) design will increase. Fluid film lubrication has been a critical issue from the outset of MEMS development, particularly in the prediction and control of viscous damping in vibrating devices such as accelerometers and gyros. Much attention has been showered on the development of models for accurate prediction of viscous damping and of fabrication techniques for minimizing the damping (which destroys the quality, or Q-factor, of a resonant system). In addition to the development and optimization of these oscillatory devices, rotating devices—micromotors, microengines, etc.—have also captured the attention of MEMS researchers since the early days of MEMS development, and there have been several demonstrations of micromotors driven by electrostatic forces [Bart et al., 1988; Mehregany et al., 1992; Nagle and Lang, 1999; Sniegowski and Garcia, 1996].
    [Show full text]