Mechanical Engineering Series

Total Page:16

File Type:pdf, Size:1020Kb

Mechanical Engineering Series Mechanical Engineering Series Frederick F. Ling Editor-in-Chief Mechanical Engineering Series A.C. Fischer-Cripps, Introduction to Contact Mechanics, 2nd ed. W. Cheng and I. Finnie, Residual Stress Measurement and the Slitting Method J. Angeles, Fundamentals of Robotic Mechanical Systems: Theory Methods and Algorithms, 3rd ed. J. Angeles, Fundamentals of Robotic Mechanical Systems: Theory, Methods, and Algorithms, 2nd ed. P. Basu, C. Kefa, and L. Jestin, Boilers and Burners: Design and Theory J.M. Berthelot, Composite Materials: Mechanical Behavior and Structural Analysis I.J. Busch-Vishniac, Electromechanical Sensors and Actuators J. Chakrabarty, Applied Plasticity K.K. Choi and N.H. Kim, Structural Sensitivity Analysis and Optimization 1: Linear Systems K.K. Choi and N.H. Kim, Structural Sensitivity Analysis and Optimization 2: Nonlinear Systems and Applications G. Chryssolouris, Laser Machining: Theory and Practice V.N. Constantinescu, Laminar Viscous Flow G.A. Costello, Theory of Wire Rope, 2nd ed. K. Czolczynski, Rotordynamics of Gas-Lubricated Journal Bearing Systems M.S. Darlow, Balancing of High-Speed Machinery W.R. DeVries, Analysis of Material Removal Processes J.F. Doyle, Nonlinear Analysis of Thin-Walled Structures: Statics, Dynamics, and Stability J.F. Doyle, Wave Propagation in Structures: Spectral Analysis Using Fast Discrete Fourier Transforms, 2nd ed. P.A. Engel, Structural Analysis of Printed Circuit Board Systems A.C. Fischer-Cripps, Introduction to Contact Mechanics A.C. Fischer-Cripps, Nanoindentation, 2nd ed. (continued after index) Anthony C. Fischer-Cripps Introduction to Contact Mechanics Second Edition 1 3 Anthony C. Fischer-Cripps Fischer-Cripps Laboratories Pty Ltd. New South Wales, Australia Introduction to Contact Mechanics, Second Edition Library of Congress Control Number: 2006939506 ISBN 0-387-68187-6 e-ISBN 0-387-68188-4 ISBN 978-0-387-68187-0 e-ISBN 978-0-387-68188-7 Printed on acid-free paper. © 2007 Springer Science+Business Media, LLC All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now know or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed in the United States of America. 9 8 7 6 5 4 3 2 1 springer.com Mechanical Engineering Series Frederick F. Ling Editor-in-Chief The Mechanical Engineering Series features graduate texts and research monographs to address the need for information in contemporary mechanical engineering, including areas of concentration of applied mechanics, biomechanics, computational mechanics, dynamical systems and control, energetics, mechanics of materials, processing, pro- duction systems, thermal science, and tribology. Advisory Board/Series Editors Applied Mechanics F.A. Leckie University of California, Santa Barbara D. Gross Technical University of Darmstadt Biomechanics V.C. Mow Columbia University Computational Mechanics H.T. Yang University of California, Santa Barbara Dynamic Systems and Control/ D. Bryant Mechatronics University of Texas at Austin Energetics J.R. Welty University of Oregon, Eugene Mechanics of Materials I. Finnie University of California, Berkeley Processing K.K. Wang Cornell University Production Systems G.-A. Klutke Texas A&M University Thermal Science A.E. Bergles Rensselaer Polytechnic Institute Tribology W.O. Winer Georgia Institute of Technology Series Preface Mechanical engineering, and engineering discipline born of the needs of the industrial revolution, is once again asked to do its substantial share in the call for industrial renewal. The general call is urgent as we face profound issues of pro- ductivity and competitiveness that require engineering solutions, among others. The Mechanical Engineering Series is a series featuring graduate texts and research monographs intended to address the need for information in contem- porary areas of mechanical engineering. The series is conceived as a comprehensive one that covers a broad range of concentrations important to mechanical engineering graduate education and research. We are fortunate to have a distinguished roster of series editors, each an expert in one of the areas of concentration. The names of the series editors are listed on page vi of this volume. The areas of concentration are applied mechanics, biomechanics, computational mechanics, dynamic systems and control, energetics, mechanics of materials, processing, thermal science, and tribology. To Dianne, Raymond and Henry Preface This book deals with the mechanics of solid bodies in contact, a subject inti- mately connected with such topics as fracture, hardness, and elasticity. Theoreti- cal work is most commonly supported by the results of indentation experiments under controlled conditions. In recent years, the indentation test has become a popular method of determining mechanical properties of both brittle and ductile materials, and particularly thin film systems. The book begins with an introduction to the mechanical properties of materi- als, general fracture mechanics, and the fracture of brittle solids. This is fol- lowed by a detailed description of indentation stress fields for both elastic and elastic-plastic contact. The discussion then turns to the formation of Hertzian cone cracks in brittle materials, subsurface damage in ductile materials, and the meaning of hardness. The book concludes with an overview of practical meth- ods of indentation. My intention is for this book to make contact mechanics accessible to those materials scientists entering the field for the first time. Experienced researchers may also benefit from the review of the most commonly used formulas and theoretical treatments of the past century. This second edition maintains the introductory character of the first with a focus on materials science as distinct from straight solid mechanics theory. Every chapter has been reviewed to make the book easier to read and more informative. A new chapter on depth sensing indentation has been added, and the contents of the other chapters have been completely overhauled with added figures, formulae and explanations. In writing this book, I have been assisted and encouraged by many col- leagues, friends, and family. I am most indebted to A. Bendeli, R.W. Cheary, R.E. Collins, R. Dukino, J.S. Field, A.K. Jämting, B.R. Lawn, C.A. Rubin, and M.V. Swain. I thank Dr. Thomas von Foerster who managed the 1st edition of this book and Dr. Alexander Greene for taking things through to this second edi- tion, and of course the production team at Springer Science+Business Media LLC for their very professional and helpful approach to the whole publication process. Lindfield, Australia Anthony C. Fischer-Cripps Contents Preface............................................................................................ ix List of Symbols........................................................................... xvii History.......................................................................................... xix Chapter 1. Mechanical Properties of Materials................................1 1.1 Introduction.............................................................................................. 1 1.2 Elasticity .................................................................................................. 1 1.2.1 Forces between atoms ................................................................... 1 1.2.2 Hooke’s law................................................................................... 2 1.2.3 Strain energy ................................................................................. 4 1.2.4 Surface energy............................................................................... 4 1.2.5 Stress.............................................................................................. 5 1.2.6 Strain ........................................................................................... 10 1.2.7 Poisson’s ratio............................................................................. 13 1.2.8 Linear elasticity (generalized Hooke’s law) ............................... 14 1.2.9 2-D Plane stress, plane strain ..................................................... 16 1.2.10 Principal stresses....................................................................... 18 1.2.11 Equations of equilibrium and compatibility.............................. 23 1.2.12 Saint-Venant’s principle............................................................ 24 1.2.13 Hydrostatic stress and stress deviation..................................... 25 1.2.14 Visualizing stresses.................................................................... 26 1.3 Plasticity ................................................................................................ 26 1.3.1 Equations of plastic flow ............................................................. 27 1.4 Stress Failure Criteria ............................................................................ 28 1.4.1 Tresca failure criterion
Recommended publications
  • 10-1 CHAPTER 10 DEFORMATION 10.1 Stress-Strain Diagrams And
    EN380 Naval Materials Science and Engineering Course Notes, U.S. Naval Academy CHAPTER 10 DEFORMATION 10.1 Stress-Strain Diagrams and Material Behavior 10.2 Material Characteristics 10.3 Elastic-Plastic Response of Metals 10.4 True stress and strain measures 10.5 Yielding of a Ductile Metal under a General Stress State - Mises Yield Condition. 10.6 Maximum shear stress condition 10.7 Creep Consider the bar in figure 1 subjected to a simple tension loading F. Figure 1: Bar in Tension Engineering Stress () is the quotient of load (F) and area (A). The units of stress are normally pounds per square inch (psi). = F A where: is the stress (psi) F is the force that is loading the object (lb) A is the cross sectional area of the object (in2) When stress is applied to a material, the material will deform. Elongation is defined as the difference between loaded and unloaded length ∆푙 = L - Lo where: ∆푙 is the elongation (ft) L is the loaded length of the cable (ft) Lo is the unloaded (original) length of the cable (ft) 10-1 EN380 Naval Materials Science and Engineering Course Notes, U.S. Naval Academy Strain is the concept used to compare the elongation of a material to its original, undeformed length. Strain () is the quotient of elongation (e) and original length (L0). Engineering Strain has no units but is often given the units of in/in or ft/ft. ∆푙 휀 = 퐿 where: is the strain in the cable (ft/ft) ∆푙 is the elongation (ft) Lo is the unloaded (original) length of the cable (ft) Example Find the strain in a 75 foot cable experiencing an elongation of one inch.
    [Show full text]
  • 6. Fracture Mechanics
    6. Fracture mechanics lead author: J, R. Rice Division of Applied Sciences, Harvard University, Cambridge MA 02138 Reader's comments on an earlier draft, prepared in consultation with J. W. Hutchinson, C. F. Shih, and the ASME/AMD Technical Committee on Fracture Mechanics, pro­ vided by A. S. Argon, S. N. Atluri, J. L. Bassani, Z. P. Bazant, S. Das, G. J. Dvorak, L. B. Freund, D. A. Glasgow, M. F. Kanninen, W. G. Knauss, D. Krajcinovic, J D. Landes, H. Liebowitz, H. I. McHenry, R. O. Ritchie, R. A. Schapery, W. D. Stuart, and R. Thomson. 6.0 ABSTRACT Fracture mechanics is an active research field that is currently advancing on many fronts. This appraisal of research trends and opportunities notes the promising de­ velopments of nonlinear fracture mechanics in recent years and cites some of the challenges in dealing with topics such as ductile-brittle transitions, failure under sub­ stantial plasticity or creep, crack tip processes under fatigue loading, and the need for new methodologies for effective fracture analysis of composite materials. Continued focus on microscale fracture processes by work at the interface of solid mechanics and materials science holds promise for understanding the atomistics of brittle vs duc­ tile response and the mechanisms of microvoid nucleation and growth in various ma­ terials. Critical experiments to characterize crack tip processes and separation mecha­ nisms are a pervasive need. Fracture phenomena in the contexts of geotechnology and earthquake fault dynamics also provide important research challenges. 6.1 INTRODUCTION cracking in the more brittle structural materials such as high strength metal alloys.
    [Show full text]
  • J-Integral Analysis of the Mixed-Mode Fracture Behaviour of Composite Bonded Joints
    J-Integral analysis of the mixed-mode fracture behaviour of composite bonded joints FERNANDO JOSÉ CARMONA FREIRE DE BASTOS LOUREIRO novembro de 2019 J-INTEGRAL ANALYSIS OF THE MIXED-MODE FRACTURE BEHAVIOUR OF COMPOSITE BONDED JOINTS Fernando José Carmona Freire de Bastos Loureiro 1111603 Equation Chapter 1 Section 1 2019 ISEP – School of Engineering Mechanical Engineering Department J-INTEGRAL ANALYSIS OF THE MIXED-MODE FRACTURE BEHAVIOUR OF COMPOSITE BONDED JOINTS Fernando José Carmona Freire de Bastos Loureiro 1111603 Dissertation presented to ISEP – School of Engineering to fulfil the requirements necessary to obtain a Master's degree in Mechanical Engineering, carried out under the guidance of Doctor Raul Duarte Salgueiral Gomes Campilho. 2019 ISEP – School of Engineering Mechanical Engineering Department JURY President Doctor Elza Maria Morais Fonseca Assistant Professor, ISEP – School of Engineering Supervisor Doctor Raul Duarte Salgueiral Gomes Campilho Assistant Professor, ISEP – School of Engineering Examiner Doctor Filipe José Palhares Chaves Assistant Professor, IPCA J-Integral analysis of the mixed-mode fracture behaviour of composite Fernando José Carmona Freire de Bastos bonded joints Loureiro ACKNOWLEDGEMENTS To Doctor Raul Duarte Salgueiral Gomes Campilho, supervisor of the current thesis for his outstanding availability, support, guidance and incentive during the development of the thesis. To my family for the support, comprehension and encouragement given. J-Integral analysis of the mixed-mode fracture behaviour of composite
    [Show full text]
  • Crack Tip Elements and the J Integral
    EN234: Computational methods in Structural and Solid Mechanics Homework 3: Crack tip elements and the J-integral Due Wed Oct 7, 2015 School of Engineering Brown University The purpose of this homework is to help understand how to handle element interpolation functions and integration schemes in more detail, as well as to explore some applications of FEA to fracture mechanics. In this homework you will solve a simple linear elastic fracture mechanics problem. You might find it helpful to review some of the basic ideas and terminology associated with linear elastic fracture mechanics here (in particular, recall the definitions of stress intensity factor and the nature of crack-tip fields in elastic solids). Also check the relations between energy release rate and stress intensities, and the background on the J integral here. 1. One of the challenges in using finite elements to solve a problem with cracks is that the stress field at a crack tip is singular. Standard finite element interpolation functions are designed so that stresses remain finite a everywhere in the element. Various types of special b c ‘crack tip’ elements have been designed that 3L/4 incorporate the singularity. One way to produce a L/4 singularity (the method used in ABAQUS) is to mesh L the region just near the crack tip with 8 noded elements, with a special arrangement of nodal points: (i) Three of the nodes (nodes 1,4 and 8 in the figure) are connected together, and (ii) the mid-side nodes 2 and 7 are moved to the quarter-point location on the element side.
    [Show full text]
  • Contact Mechanics in Gears a Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’S Thesis in Product Development
    Two Contact Mechanics in Gears A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’s Thesis in Product Development MARCUS SLOGÉN Department of Product and Production Development Division of Product Development CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden, 2013 MASTER’S THESIS IN PRODUCT DEVELOPMENT Contact Mechanics in Gears A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Marcus Slogén Department of Product and Production Development Division of Product Development CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2013 Contact Mechanics in Gear A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears MARCUS SLOGÉN © MARCUS SLOGÉN 2013 Department of Product and Production Development Division of Product Development Chalmers University of Technology SE-412 96 Göteborg Sweden Telephone: + 46 (0)31-772 1000 Cover: The picture on the cover page shows the contact stress distribution over a crowned spur gear tooth. Department of Product and Production Development Göteborg, Sweden 2013 Contact Mechanics in Gears A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’s Thesis in Product Development MARCUS SLOGÉN Department of Product and Production Development Division of Product Development Chalmers University of Technology ABSTRACT Computer Aided Engineering, CAE, is becoming more and more vital in today's product development. By using reliable and efficient computer based tools it is possible to replace initial physical testing. This will result in cost savings, but it will also reduce the development time and material waste, since the demand of physical prototypes decreases. This thesis shows how a computer program for analyzing contact mechanics in spur and helical gears has been developed at the request of Vicura AB.
    [Show full text]
  • Cookbook for Rheological Models ‒ Asphalt Binders
    CAIT-UTC-062 Cookbook for Rheological Models – Asphalt Binders FINAL REPORT May 2016 Submitted by: Offei A. Adarkwa Nii Attoh-Okine PhD in Civil Engineering Professor Pamela Cook Unidel Professor University of Delaware Newark, DE 19716 External Project Manager Karl Zipf In cooperation with Rutgers, The State University of New Jersey And State of Delaware Department of Transportation And U.S. Department of Transportation Federal Highway Administration Disclaimer Statement The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program, in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. The Center for Advanced Infrastructure and Transportation (CAIT) is a National UTC Consortium led by Rutgers, The State University. Members of the consortium are the University of Delaware, Utah State University, Columbia University, New Jersey Institute of Technology, Princeton University, University of Texas at El Paso, Virginia Polytechnic Institute, and University of South Florida. The Center is funded by the U.S. Department of Transportation. TECHNICAL REPORT STANDARD TITLE PAGE 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. CAIT-UTC-062 4. Title and Subtitle 5. Report Date Cookbook for Rheological Models – Asphalt Binders May 2016 6. Performing Organization Code CAIT/University of Delaware 7. Author(s) 8. Performing Organization Report No. Offei A. Adarkwa Nii Attoh-Okine CAIT-UTC-062 Pamela Cook 9. Performing Organization Name and Address 10.
    [Show full text]
  • AC Fischer-Cripps
    A.C. Fischer-Cripps Introduction to Contact Mechanics Series: Mechanical Engineering Series ▶ Includes a detailed description of indentation stress fields for both elastic and elastic-plastic contact ▶ Discusses practical methods of indentation testing ▶ Supported by the results of indentation experiments under controlled conditions Introduction to Contact Mechanics, Second Edition is a gentle introduction to the mechanics of solid bodies in contact for graduate students, post doctoral individuals, and the beginning researcher. This second edition maintains the introductory character of the first with a focus on materials science as distinct from straight solid mechanics theory. Every chapter has been 2nd ed. 2007, XXII, 226 p. updated to make the book easier to read and more informative. A new chapter on depth sensing indentation has been added, and the contents of the other chapters have been completely overhauled with added figures, formulae and explanations. Printed book Hardcover ▶ 159,99 € | £139.99 | $199.99 The author begins with an introduction to the mechanical properties of materials, ▶ *171,19 € (D) | 175,99 € (A) | CHF 189.00 general fracture mechanics and the fracture of brittle solids. This is followed by a detailed description of indentation stress fields for both elastic and elastic-plastic contact. The discussion then turns to the formation of Hertzian cone cracks in brittle materials, eBook subsurface damage in ductile materials, and the meaning of hardness. The author Available from your bookstore or concludes with an overview of practical methods of indentation. ▶ springer.com/shop MyCopy Printed eBook for just ▶ € | $ 24.99 ▶ springer.com/mycopy Order online at springer.com ▶ or for the Americas call (toll free) 1-800-SPRINGER ▶ or email us at: [email protected].
    [Show full text]
  • Idealized 3D Auxetic Mechanical Metamaterial: an Analytical, Numerical, and Experimental Study
    materials Article Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study Naeim Ghavidelnia 1 , Mahdi Bodaghi 2 and Reza Hedayati 3,* 1 Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran 1591634311, Iran; [email protected] 2 Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK; [email protected] 3 Novel Aerospace Materials, Faculty of Aerospace Engineering, Delft University of Technology (TU Delft), Kluyverweg 1, 2629 HS Delft, The Netherlands * Correspondence: [email protected] or [email protected] Abstract: Mechanical metamaterials are man-made rationally-designed structures that present un- precedented mechanical properties not found in nature. One of the most well-known mechanical metamaterials is auxetics, which demonstrates negative Poisson’s ratio (NPR) behavior that is very beneficial in several industrial applications. In this study, a specific type of auxetic metamaterial structure namely idealized 3D re-entrant structure is studied analytically, numerically, and experi- mentally. The noted structure is constructed of three types of struts—one loaded purely axially and two loaded simultaneously flexurally and axially, which are inclined and are spatially defined by angles q and j. Analytical relationships for elastic modulus, yield stress, and Poisson’s ratio of the 3D re-entrant unit cell are derived based on two well-known beam theories namely Euler–Bernoulli and Timoshenko. Moreover, two finite element approaches one based on beam elements and one based on volumetric elements are implemented. Furthermore, several specimens are additively Citation: Ghavidelnia, N.; Bodaghi, manufactured (3D printed) and tested under compression.
    [Show full text]
  • Fracture and Deformation of Soft Materials and Structures
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2018 Fracture and deformation of soft am terials and structures Zhuo Ma Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Aerospace Engineering Commons, Engineering Mechanics Commons, Materials Science and Engineering Commons, and the Mechanics of Materials Commons Recommended Citation Ma, Zhuo, "Fracture and deformation of soft am terials and structures" (2018). Graduate Theses and Dissertations. 16852. https://lib.dr.iastate.edu/etd/16852 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Fracture and deformation of soft materials and structures by Zhuo Ma A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Engineering Mechanics Program of Study Committee: Wei Hong, Co-major Professor Ashraf Bastawros, Co-major Professor Pranav Shrotriya Liang Dong Liming Xiong The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this dissertation. The Graduate College will ensure this dissertation is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2018 Copyright © Zhuo Ma, 2018. All rights reserved. ii TABLE OF CONTENTS Page LIST OF FIGURES ..........................................................................................................
    [Show full text]
  • RHEOLOGY and DYNAMIC MECHANICAL ANALYSIS – What They Are and Why They’Re Important
    RHEOLOGY AND DYNAMIC MECHANICAL ANALYSIS – What They Are and Why They’re Important Presented for University of Wisconsin - Madison by Gregory W Kamykowski PhD TA Instruments May 21, 2019 TAINSTRUMENTS.COM Rheology: An Introduction Rheology: The study of the flow and deformation of matter. Rheological behavior affects every aspect of our lives. Dynamic Mechanical Analysis is a subset of Rheology TAINSTRUMENTS.COM Rheology: The study of the flow and deformation of matter Flow: Fluid Behavior; Viscous Nature F F = F(v); F ≠ F(x) Deformation: Solid Behavior F Elastic Nature F = F(x); F ≠ F(v) 0 1 2 3 x Viscoelastic Materials: Force F depends on both Deformation and Rate of Deformation and F vice versa. TAINSTRUMENTS.COM 1. ROTATIONAL RHEOLOGY 2. DYNAMIC MECHANICAL ANALYSIS (LINEAR TESTING) TAINSTRUMENTS.COM Rheological Testing – Rotational - Unidirectional 2 Basic Rheological Methods 10 1 10 0 1. Apply Force (Torque)and 10 -1 measure Deformation and/or 10 -2 (rad/s) Deformation Rate (Angular 10 -3 Displacement, Angular Velocity) - 10 -4 Shear Rate Shear Controlled Force, Controlled 10 3 10 4 10 5 Angular Velocity, Velocity, Angular Stress Torque, (µN.m)Shear Stress 2. Control Deformation and/or 10 5 Displacement, Angular Deformation Rate and measure 10 4 10 3 Force needed (Controlled Strain (Pa) ) Displacement or Rotation, 10 2 ( Controlled Strain or Shear Rate) 10 1 Torque, Stress Torque, 10 -1 10 0 10 1 10 2 10 3 s (s) TAINSTRUMENTS.COM Steady Simple Shear Flow Top Plate Velocity = V0; Area = A; Force = F H y Bottom Plate Velocity = 0 x vx = (y/H)*V0 .
    [Show full text]
  • 1 Classical Theory and Atomistics
    1 1 Classical Theory and Atomistics Many research workers have pursued the friction law. Behind the fruitful achievements, we found enormous amounts of efforts by workers in every kind of research field. Friction research has crossed more than 500 years from its beginning to establish the law of friction, and the long story of the scientific historyoffrictionresearchisintroducedhere. 1.1 Law of Friction Coulomb’s friction law1 was established at the end of the eighteenth century [1]. Before that, from the end of the seventeenth century to the middle of the eigh- teenth century, the basis or groundwork for research had already been done by Guillaume Amontons2 [2]. The very first results in the science of friction were found in the notes and experimental sketches of Leonardo da Vinci.3 In his exper- imental notes in 1508 [3], da Vinci evaluated the effects of surface roughness on the friction force for stone and wood, and, for the first time, presented the concept of a coefficient of friction. Coulomb’s friction law is simple and sensible, and we can readily obtain it through modern experimentation. This law is easily verified with current exper- imental techniques, but during the Renaissance era in Italy, it was not easy to carry out experiments with sufficient accuracy to clearly demonstrate the uni- versality of the friction law. For that reason, 300 years of history passed after the beginning of the Italian Renaissance in the fifteenth century before the friction law was established as Coulomb’s law. The progress of industrialization in England between 1750 and 1850, which was later called the Industrial Revolution, brought about a major change in the production activities of human beings in Western society and later on a global scale.
    [Show full text]
  • What Engineers Should Know About Bending Steel
    bending and rolling What Engineers Should Know About Bending Steel With these tips under your belt, you’ll be ahead of the curve on your next bending or rolling project. BY TODD A. ALWOOD HOW MUCH DO YOU KNOW ABOUT BENDING STRUCTURAL STEEL? Do you know what you need to show on con- struction drawings to transfer the idea of what the result should actually look like? Do you know how tight of a radius you Hcan roll a W12×19, and what to expect it to look like? If you have bending questions, who do you ask? AISC’s bender-roller com- mittee is taking steps to address these ques- tions, which are coming up more and more within the structural steel industry. Bender = Fabricator? Not so! The bender is typically a spe- cialty subcontractor of the fabricator. Benders receive the steel from the fabri- cator (or sometimes furnish it themselves), and then ship the curved steel back to the fabricator. Benders usually have limited fabrication capabilities, such as hole drill- ing and plate welding, but they are gener- ally used for smaller jobs that usually are not structural in nature. Typical fabrication is still carried out through the main project fabricator who organizes the steel package from procurement through delivery to the site for erection. Kottler Metal Products, Inc. Kottler Metal Products, Todd Alwood is the senior advisor for AISC’s Steel Solutions Center and is Secretary of AISC’s Bender-Roller Committee. MODERN STEEL CONSTRUCTION MAY 2006 Common Terminology and Essential Dimensions for Curving Common Hot-Rolled Shapes There’s only one type of bending, right? Nope! There are five typical methods of bending in the industry: roll- ing, incremental bending, hot bending, rotary-draw bending, and induc- tion bending.
    [Show full text]