Mechanical Engineering Principles

313 Pages · 2012 · 4.22 MB · English

  • Mechanical Engineering Principles

    Mechanical Engineering Principles

    Second Edition

    Why are competent engineers so vital?

    Engineering is among the most important of all professions. It is the authors’ opinions that engineers save

    more lives than medical doctors (physicians). For example, poor water or the lack of it, is the second largest

    cause of human death in the world, and if engineers are given the tools, they can solve this problem. The

    largest cause of human death is caused by the malarial mosquito, and even death due to malaria can be

    decreased by engineers - by providing helicopters for spraying areas infected by the mosquito and making and

    designing medical syringes and pills to protect people against catching all sorts of diseases. Most medicines

    are produced by engineers! How does the engineer put 1 mg of ‘medicine’ precisely and individually into

    millions of pills, at an affordable price?

    Moreover, one of the biggest contributions by humankind was the design of the agricultural tractor, which

    was designed and built by engineers to increase food production many-fold for a human population which

    more-or-less quadruples every century! It is also interesting to note that the richest countries in the world are

    very heavily industrialised. Engineers create wealth! Most other professions don’t!

    Even in blue sky projects, engineers play a major role. For example, most rocket scientists are chartered

    engineers or their equivalents and Americans call their Chartered Engineers (and their equivalents), scientists.

    Astronomers are space scientists and not rocket scientists; they could not design a rocket to conquer outer

    space. Even modern theoretical physicists are mainly interested in astronomy and cosmology and also nuclear

    science. In general a theoretical physicist cannot, without special training, design a submarine structure to

    dive to the bottom of the Mariana Trench, which is 11.52 km or 7.16 miles deep, or design a very long bridge,

    a tall city skyscraper or a rocket to conquer outer space.

    This book presents a solid foundation for the reader in mechanical engineering principles, on which s/he

    can safely build tall buildings and long bridges that may last for a thousand years or more. It is the authors’

    experience that it is most unwise to attempt to build such structures on shaky foundations; they may come

    tumbling down - with disastrous consequences.

    John O. Bird is the former Head of Applied Electronics in the Faculty of Technology at Highbury College,

    Portsmouth, U.K. More recently, he has combined freelance lecturing at the University of Portsmouth, with Examiner

    responsibilities for Advanced Mathematics with City & Guilds, and examining for the International Baccalaureate

    Organisation. He is the author of some 120 textbooks on engineering and mathematical subjects with worldwide sales

    approaching 1 million copies. He is currently a Senior Training Provider at the Royal Naval School of Marine

    Engineering in the Defence College of Marine and Air Engineering at H.M.S. Sultan, Gosport, Hampshire, U.K.

    Carl T. F. Ross gained his fi rst degree in Naval Architecture, from King’s College, Durham University; his PhD in

    Structural Engineering from the Victoria University of Manchester; and was awarded his DSc in Ocean Engineering

    from the CNAA, London. His research in the fi eld of engineering led to advances in the design of submarine pressure

    hulls. His publications to date exceed some 270 papers and books and he is Professor of Structural Dynamics at the

    University of Portsmouth, U.K.

    See Carl Ross’s website below, which has an enormous content on science, technology and education.

    http://homepage.ntlworld.com/carl.ross/page3.htm Mechanical Engineering Principles

    Second Edition

    John O. Bird, BSc(Hons), CEng, CMath, CSci, FIMA, FITE, FCollT

    Carl T. F. Ross, BSc(Hons), PhD, DSc, CEng, FRINA, MSNAME Second edition published 2012

    by Routledge

    2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN

    Simultaneously published in the USA and Canada

    by Routledge

    711 Third Avenue, New York, NY 10017

    Routledge is an imprint of the Taylor & Francis Group, an informa business

    © 2012 John O. Bird and Carl T. F. Ross

    The right of John O. Bird and Carl T. F. Ross to be identified as authors of this work has been asserted by them in

    accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.

    All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic,

    mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any

    information storage or retrieval system, without permission in writing from the publishers.

    This publication presents material of a broad scope and applicability. Despite stringent efforts by all concerned in the

    publishing process, some typographical or editorial errors may occur, and readers are encouraged to bring these to our

    attention where they represent errors of substance. The publisher and author disclaim any liability, in whole or in part,

    arising from information contained in this publication. The reader is urged to consult with an appropriate licensed

    professional prior to taking any action or making any interpretation that is within the realm of a licensed professional


    First edition published by Elsevier in 2002

    Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for

    identification and explanation without intent to infringe.

    British Library Cataloguing in Publication Data

    A catalogue record for this book is available from the British Library

    Library of Congress Cataloguing in Publication Data

    A catalog record for this title has been requested

    ISBN: 9780415517850 (pbk)

    ISBN: 9780203121146 (ebk)

    Typeset in Times

    by RefineCatch Limited, Bungay, Suffolk Contents

    Preface ix 4.3 Forces 47

    4.4 The resultant of two coplanar forces 48

    4.5 Triangle of forces method 48

    Part One Revision of Mathematics 1

    4.6 The parallelogram of forces method 50

    4.7 Resultant of coplanar forces by

    1 Revisionary Mathematics 3

    calculation 50

    1.1 Introduction 3

    4.8 Resultant of more than two

    1.2 Radians and degrees 3

    coplanar forces 51

    1.3 Measurement of angles 4

    4.9 Coplanar forces in equilibrium 53

    1.4 Triangle calculations 5

    4.10 Resolution of forces 54

    1.5 Brackets 7

    4.11 Summary 58

    1.6 Fractions 8

    1.7 Percentages 9 5 Simply supported beams 61

    1.8 Laws of indices 11 5.1 The moment of a force 61

    1.9 Simultaneous equations 14 5.2 E quilibrium and the principle of

    moments 62

    Revision Test 1 Revisionary mathematics 18 5.3 S imply supported beams

    having point loads 64

    5.4 Simply supported beams with couples 68

    Part Two Statics and Strength

    Revision Test 2 F orces, tensile testing

    of Materials 21

    and beams 72

    2 The effects of forces on materials 23

    2.1 Introduction 23 6 Forces in structures 73

    2.2 Tensile force 24 6.1 Introduction 73

    2.3 Compressive force 24 6.2 W orked problems on mechanisms

    2.4 Shear force 24 and pin-jointed trusses 74

    2.5 Stress 24 6.3 Graphical method 75

    2.6 Strain 25 6.4 Method of joints

    2.7 E lasticity, limit of proportionality (a mathematical method) 79

    and elastic limit 27 6.5 The method of sections

    2.8 Hooke’s law 28 (a mathematical method) 84

    2.9 Ductility, brittleness and malleability 32

    2.10 Modulus of rigidity 32 7 Bending moment and shear force diagrams 87

    2.11 Thermal strain 33 7.1 Bending moment (M) 87

    2.12 Compound bars 33 7.2 Shearing force (F) 87

    7.3 Worked problems on bending

    3 Tensile testing 39 moment and shearing force diagrams 88

    3.1 The tensile test 39 7.4 Uniformly distributed loads 97

    3.2 Worked problems on tensile testing 40

    3.3 Further worked problems on 8 First and second moments of areas 102

    tensile testing 42 8.1 Centroids 102

    3.4 Proof stress 44 8.2 The first moment of area 102

    8.3 C entroid of area between a curve

    4 Forces acting at a point 46 and the x-axis 103

    4.1 Scalar and vector quantities 46 8.4 C entroid of area between a

    4.2 Centre of gravity and equilibrium 46 curve and the y-axis 103 vi Contents

    8.5 W orked problems on centroids of 14.4 Rotation of a rigid body about a fixed axis 167

    simple shapes 104 14.5 Moment of inertia (I) 167

    8.6 F urther worked problems on centroids

    of simple shapes 105 15 Work, energy and power 170

    8.7 S econd moments of area of 15.1 Work 170

    regular sections 106 15.2 Energy 174

    8.8 S econd moment of area for 15.3 Power 175

    ‘built-up’ sections 113 15.4 Potential and kinetic energy 178

    15.5 Kinetic energy of rotation 181

    Revision Test 3 Forces in structures,

    bending moment and shear Revision Test 5 L inear and angular motion,

    force diagrams, and second m omentum and impulse,

    moments of area 119 force, mass and acceleration,

    work, energy and power 184

    9 Bending of beams 120

    9.1 Introduction 120 16 Friction 185

    9.2 To prove that s = M = E 121 16.1 Introduction to friction 185

    y I R

    16.2 Coefficient of friction 186

    9.3 W orked problems on the bending

    16.3 Applications of friction 187

    of beams 122

    16.4 Friction on an inclined plane 188

    16.5 M otion up a plane with the pulling

    10 Torque 126

    force P parallel to the plane 188

    10.1 Couple and torque 126

    16.6 M otion down a plane with the

    10.2 W ork done and power transmitted

    pulling force P parallel to the plane 189

    by a constant torque 127

    16.7 M otion up a plane due to a horizontal

    10.3 Kinetic energy and moment of inertia 129

    force P 189

    10.4 Power transmission and efficiency 132

    16.8 The efficiency of a screw jack 192

    11 Twisting of shafts 136

    17 Motion in a circle 196

    t T Gθ

    11.1 To prove that = = 136 17.1 Introduction 196

    r J L

    17.2 Motion on a curved banked track 198

    11.2 Worked problems on the

    17.3 Conical pendulum 199

    twisting of shafts 138

    17.4 Motion in a vertical circle 201

    17.5 Centrifugal clutch 203

    Revision Test 4 Bending of beams, torque

    and twisting of shafts 142

    18 Simple harmonic motion 205

    18.1 Introduction to simple

    harmonic motion (SHM) 205

    Part Three Dynamics 143 18.2 The spring-mass system 206

    18.3 The simple pendulum 208

    12 Linear and angular motion 145 18.4 The compound pendulum 209

    12.1 The radian 145 18.5 Torsional vibrations 210

    12.2 Linear and angular velocity 145

    12.3 Linear and angular acceleration 147 19 Simple machines 212

    12.4 Further equations of motion 148 19.1 Machines 212

    12.5 Relative velocity 150 19.2 F orce ratio, movement ratio and efficiency 212

    19.3 Pulleys 214

    13 Linear momentum and impulse 154 19.4 The screw-jack 216

    13.1 Linear momentum 154 19.5 Gear trains 216

    13.2 Impulse and impulsive forces 157 19.6 Levers 218

    14 Force, mass and acceleration 162 Revision Test 6 Friction, motion in a circle,

    14.1 Introduction 162 simple harmonic motion and

    14.2 Newton’s laws of motion 163 simple machines 222

    14.3 Centripetal acceleration 165 Contents vii

    23.4 Flow nozzle 263

    Part Four Heat Transfer and Fluid 23.5 Pitot-static tube 263

    Mechanics 223 23.6 Mechanical flowmeters 264

    23.7 Deflecting vane flowmeter 264

    20 Heat energy and transfer 225 23.8 Turbine type meters 264

    20.1 Introduction 225 23.9 Float and tapered-tube meter 265

    20.2 The measurement of temperature 226 23.10 Electromagnetic flowmeter 266

    20.3 Specific heat capacity 226 23.11 Hot-wire anemometer 266

    20.4 Change of state 228 23.12 Choice of flowmeter 267

    20.5 Latent heats of fusion and vaporisation 229 23.13 Equation of continuity 267

    20.6 A simple refrigerator 231 23.14 Bernoulli’s equation 267

    20.7 Conduction, convection and radiation 231 23.15 Impact of a jet on a stationary plate 269

    20.8 Vacuum flask 232

    20.9 Use of insulation in conserving fuel 232 24 Ideal gas laws 272

    24.1 Boyle’s law 272

    21 Thermal expansion 235 24.2 Charles’ law 273

    21.1 Introduction 235 24.3 The pressure law 274

    21.2 P ractical applications of 24.4 Dalton’s law of partial pressure 275

    thermal expansion 235 24.5 Characteristic gas equation 275

    21.3 Expansion and contraction of water 236 24.6 Worked problems on the

    21.4 Coefficient of linear expansion 236 characteristic gas equation 275

    21.5 Coefficient of superficial expansion 238 24.7 Further worked problems on the

    21.6 Coefficient of cubic expansion 239 characteristic gas equation 277

    25 The measurement of temperature 281

    Revision Test 7 Heat energy and transfer,

    25.1 Liquid-in-glass thermometer 281

    and thermal expansion 243

    25.2 Thermocouples 282

    25.3 Resistance thermometers 284

    22 Hydrostatics 244 25.4 Thermistors 286

    22.1 Pressure 244 25.5 Pyrometers 286

    22.2 Fluid pressure 245 25.6 T emperature indicating paints

    22.3 Atmospheric pressure 247 and crayons 287

    22.4 Archimedes’ principle 248 25.7 Bimetallic thermometers 288

    22.5 Measurement of pressure 249 25.8 Mercury-in-steel thermometer 288

    22.6 Barometers 249 25.9 Gas thermometers 288

    22.7 Absolute and gauge pressure 251 25.10 Choice of measuring devices 288

    22.8 The manometer 252

    22.9 The Bourdon pressure gauge 253 Revision Test 8 Hydrostatics, fluid flow,

    22.10 Vacuum gauges 253 gas laws and temperature

    22.11 Hydrostatic pressure on measurement 290

    submerged surfaces 254

    22.12 Hydrostatic thrust on curved surfaces 255

    A list of formulae for mechanical

    22.13 Buoyancy 255

    engineering principles 291

    22.14 The stability of floating bodies 255

    Greek alphabet 296

    23 Fluid flow 261

    23.1 Differential pressure flowmeters 261 Answers to multiple-choice questions 297

    23.2 Orifice plate 262

    23.3 Venturi tube 262 Index 299 Preface

    Mechanical Engineering Principles 2nd Edition aims Although pre-requisites for the modules covered

    to broaden the reader’s knowledge of the basic principles in this book include Foundation Certificate/ diploma,

    that are fundamental to mechanical engineering design or similar, in Mathematics and Science, each topic

    and the operation of mechanical systems. considered in the text is presented in a way that

    assumes that the reader has little previous

    Modern engineering systems and products still rely

    knowledge of that topic.

    upon static and dynamic principles to make them work.

    Even systems that appear to be entirely electronic have a Mechanical Engineering Principles 2nd Edition

    physical presence governed by the principles of statics. contains over 325 worked problems, followed by

    In this second edition of Mechanical Engineering over 550 further problems (all with answers).

    Principles, a chapter has been added on revisionary The further problems are contained within some

    mathematics; it is not possible to progress in engineering 140 Exercises; each Exercise follows on directly

    studies without a reasonable knowledge of mathematics, from the relevant section of work, every few

    a fact that soon becomes obvious to both students and pages. In addition, the text contains 276 multiple-

    teachers alike. It is therefore hoped that this chapter on choice questions (all with answers), and 260 short

    basic mathematics revision will be helpful and make answer questions, the answers for which can be

    the engineering studies more comprehensible. Minor determined from the preceding material in that particular

    modifications and some further worked problems have chapter. Where at all possible, the problems mirror

    also been added throughout the text. practical situations found in mechanical engineering.

    371 line diagrams enhance the understanding of the

    Free Internet downloads of full solutions to the fur-


    ther problems and a PowerPoint presentation of all

    the illustrations contained in the text is available – see At regular intervals throughout the text are some

    page x. 8 Revision Tests to check understanding. For example,

    Revision Test 1 covers material contained in Chapter

    For clarity, the text is divided into four parts, these

    1, Test 2 covers the material in Chapters 2 to 5, and


    so on. No answers are given for the questions in the

    Part 1 Revision of Mathematics Revision Tests, but a Lecturer’s guide has been

    Part 2 Statics and strength of materials produced giving full solutions and suggested marking

    Part 3 Dynamics scheme. The guide is offered online free to lecturer’s/

    Part 4 Heat transfer and fluid mechanics instructor’s – see below.

    Mechanical Engineering Principles 2nd Edition is At the end of the text, a list of relevant formulae is

    suitable for the following: included for easy reference.

    (i) National Certificate/Diploma courses in ‘Learning by Example’ is at the heart of Mechanical

    Mechanical Engineering Engineering Principles, 2nd Edition.

    (ii) Undergraduate courses in Mechanical,

    Civil, Structural, Aeronautical & Marine JOHN BIRD

    Engineering, together with Naval Architecture Royal Naval School of Marine Engineering,

    (iii) Any introductory/access/foundation course HMS Sultan, formerly

    involving Mechanical Engineering Principles University of Portsmouth and Highbury

    at University, and Colleges of Further and College, Portsmouth

    Higher education. CARL ROSS Professor, University of Portsmouth

    Please note: To fully download this free PDF,EBook files you need know All free.
    Found by internet command,site not saved pdf file
You May Also Like

Related PPT Template in the same category.