Materials Selection in Mechanical Design Third Edition PDF

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Materials Selection in Mechanical Design Third Edition Michael F. Ashby AMSTERDAM
BOSTON
HEIDELBERG
LONDON
NEW YORK
OXFORD PARIS
SAN DIEGO
SAN FRANCISCO
SINGAPORE
SYDNEY
TOKYO Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 30 Corporate Drive, Burlington, MA 018...

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Materials Selection in Mechanical Design Third Edition

Michael F. Ashby

AMSTERDAM
BOSTON
HEIDELBERG
LONDON
NEW YORK
OXFORD PARIS
SAN DIEGO
SAN FRANCISCO
SINGAPORE
SYDNEY
TOKYO

Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 30 Corporate Drive, Burlington, MA 01803 First published by Pergamon Press 1992 Second edition 1999 Third edition 2005 Copyright

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1992, 1999, 2005 Michael F. Ashby. All rights reserved

The right of Michael F. Ashby to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1T 4LP. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publisher Permissions may be sought directly from Elsevier’s Science and Technology Rights Department in Oxford, UK: phone: (þ44) (0) 1865 843830, fax: (þ44) 1865 853333, e-mail: [email protected]. You may also complete your request on-line via the Elsevier homepage (http://www.elsevier.com), by selecting ‘Customer Support’ and then ‘Obtaining Permissions’ British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress ISBN 0 7506 6168 2 For information on all Elsevier Butterworth-Heinemann publications visit our website at http://books.elsevier.com Typeset by Newgen Imaging Systems (P) Ltd, Chennai, India Printed and bound in Italy

Working together to grow libraries in developing countries www.elsevier.com | www.bookaid.org | www.sabre.org

Preface Materials, of themselves, affect us little; it is the way we use them which influences our lives. Epictetus, AD 50–100, Discourses Book 2, Chapter 5.

New materials advanced engineering design in Epictetus’ time. Today, with more materials than ever before, the opportunities for innovation are immense. But advance is possible only if a procedure exists for making a rational choice. This book develops a systematic procedure for selecting materials and processes, leading to the subset which best matches the requirements of a design. It is unique in the way the information it contains has been structured. The structure gives rapid access to data and allows the user great freedom in exploring the potential of choice. The method is available as software,1 giving greater flexibility. The approach emphasizes design with materials rather than materials ‘‘science’’, although the underlying science is used, whenever possible, to help with the structuring of criteria for selection. The first eight chapters require little prior knowledge: a first-year grasp of materials and mechanics is enough. The chapters dealing with shape and multi-objective selection are a little more advanced but can be omitted on a first reading. As far as possible the book integrates materials selection with other aspects of design; the relationship with the stages of design and optimization and with the mechanics of materials, are developed throughout. At the teaching level, the book is intended as the text for 3rd and 4th year engineering courses on Materials for Design: a 6–10 lecture unit can be based on Chapters 1–6; a full 20þ lecture course, with associated project work with the associated software, uses the entire book. Beyond this, the book is intended as a reference text of lasting value. The method, the charts and tables of performance indices have application in real problems of materials and process selection; and the catalogue of ‘‘useful solutions’’ is particularly helpful in modelling — an essential ingredient of optimal design. The reader can use the book (and the software) at increasing levels of sophistication as his or her experience grows, starting with the material indices developed in the case studies of the text, and graduating to the modelling of new design problems, leading to new material indices and penalty functions, and new — and perhaps novel — choices of material. This continuing education aspect is helped by a list of Further reading at the end of most chapters, and by a set of exercises in Appendix E covering all aspects of the text. Useful reference material is assembled in appendices at the end of the book. Like any other book, the contents of this one are protected by copyright. Generally, it is an infringement to copy and distribute materials from a copyrighted source. But the best way to use the charts that are a central feature of the book is to have a clean copy on which you can draw, try out alternative selection criteria, write comments, and so forth; and presenting the conclusion of a selection exercise is often most easily done in the same way. Although the book itself is copyrighted, the reader is authorized to make unlimited copies of the charts, and to reproduce these, with proper reference to their source, as he or she wishes. M.F. Ashby Cambridge, July 2004 1 The CES materials and process selection platform, available from Granta Design Ltd, Rustat House, 62 Clifton Road, Cambridge CB1 7EG, UK (www.grantadesign.com).

Acknowledgements Many colleagues have been generous in discussion, criticism, and constructive suggestions. I particularly wish to thank Professor Yves Bre´chet of the University of Grenoble; Professor Anthony Evans of the University of California at Santa Barbara; Professor John Hutchinson of Harvard University; Dr David Cebon; Professor Norman Fleck; Professor Ken Wallace; Dr. John Clarkson; Dr. Hugh Shercliff of the Engineering Department, Cambridge University; Dr Amal Esawi of the American University in Cairo, Egypt; Dr Ulrike Wegst of the Max Planck Institute for Materials Research in Stuttgart, Germany; Dr Paul Weaver of the Department of Aeronautical Engineering at the University of Bristol; Professor Michael Brown of the Cavendish Laboratory, Cambridge, UK, and the staff of Granta Design Ltd, Cambridge, UK.

Features of the Third Edition Since publication of the Second Edition, changes have occurred in the fields of materials and mechanical design, as well as in the way that these and related subjects are taught within a variety of curricula and courses. This new edition has been comprehensively revised and reorganized to address these. Enhancements have been made to presentation, including a new layout and twocolour design, and to the features and supplements that accompany the text. The key changes are outlined below.

Key changes New and fully revised chapters:          

Processes and process selection (Chapter 7) Process selection case studies (Chapter 8) Selection of material and shape (Chapter 11) Selection of material and shape: case studies (Chapter 12) Designing hybrid materials (Chapter 13) Hybrid case studies (Chapter 14) Information and knowledge sources for design (Chapter 15) Materials and the environment (Chapter 16) Materials and industrial design (Chapter 17) Comprehensive appendices listing useful formulae; data for material properties; material indices; and information sources for materials and processes.

Supplements to the Third Edition Material selection charts Full color versions of the material selection charts presented in the book are available from the following website. Although the charts remain copyright of the author, users of this book are authorized to download, print and make unlimited copies of these charts, and to reproduce these for teaching and learning purposes only, but not for publication, with proper reference to their ownership and source. To access the charts and other teaching resources, visit www.grantadesign.com/ ashbycharts.htm

Instructor’s manual The book itself contains a comprehensive set of exercises. Worked-out solutions to the exercises are freely available to teachers and lecturers who adopt this book. To access this material online please visit http://books.elsevier.com/manuals and follow the instructions on screen.

xiv

Features of the Third Edition

Image bank The Image Bank provides adopting tutors and lecturers with PDF versions of the figures from the book that may be used in lecture slides and class presentations. To access this material please visit http://books.elsevier.com/manuals and follow the instructions on screen.

The CES EduPack CES EduPack is the software-based package to accompany this book, developed by Michael Ashby and Granta Design. Used together, Materials Selection in Mechanical Design and CES EduPack provide a complete materials, manufacturing and design course. For further information please see the last page of this book, or visit www.grantadesign.com.

Contents

Preface Acknowledgements Features of the Third Edition

xi xii xiii

1

Introduction 1.1 Introduction and synopsis 1.2 Materials in design 1.3 The evolution of engineering materials 1.4 Case study: the evolution of materials in vacuum cleaners 1.5 Summary and conclusions 1.6 Further reading

2

The 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8

3

Engineering materials and their properties 3.1 Introduction and synopsis 3.2 The families of engineering materials 3.3 The definitions of material properties 3.4 Summary and conclusions 3.5 Further reading

27 28 28 30 43 44

4

Material property charts 4.1 Introduction and synopsis 4.2 Exploring material properties 4.3 The material property charts 4.4 Summary and conclusions 4.5 Further reading

45 46 46 50 77 78

5

Materials selection — the basics 5.1 Introduction and synopsis 5.2 The selection strategy 5.3 Attribute limits and material indices 5.4 The selection procedure

79 80 81 85 93

design process Introduction and synopsis The design process Types of design Design tools and materials data Function, material, shape, and process Case study: devices to open corked bottles Summary and conclusions Further reading

1 2 2 4 6 8 8 11 12 12 16 17 19 20 24 25

vi

Contents

5.5 5.6 5.7 5.8

Computer-aided selection The structural index Summary and conclusions Further reading

99 102 103 104

6

Materials selection — case studies 6.1 Introduction and synopsis 6.2 Materials for oars 6.3 Mirrors for large telescopes 6.4 Materials for table legs 6.5 Cost: structural material for buildings 6.6 Materials for flywheels 6.7 Materials for springs 6.8 Elastic hinges and couplings 6.9 Materials for seals 6.10 Deflection-limited design with brittle polymers 6.11 Safe pressure vessels 6.12 Stiff, high damping materials for shaker tables 6.13 Insulation for short-term isothermal containers 6.14 Energy-efficient kiln walls 6.15 Materials for passive solar heating 6.16 Materials to minimize thermal distortion in precision devices 6.17 Nylon bearings for ships’ rudders 6.18 Materials for heat exchangers 6.19 Materials for radomes 6.20 Summary and conclusions 6.21 Further reading

105 106 106 110 114 117 121 126 130 133 136 140 144 147 151 154 157 160 163 168 172 172

7

Processes and process selection 7.1 Introduction and synopsis 7.2 Classifying processes 7.3 The processes: shaping, joining, and finishing 7.4 Systematic process selection 7.5 Ranking: process cost 7.6 Computer-aided process selection 7.7 Supporting information 7.8 Summary and conclusions 7.9 Further reading

175 176 177 180 195 202 209 215 215 216

8

Process selection case studies 8.1 Introduction and synopsis 8.2 Forming a fan 8.3 Fabricating a pressure vessel 8.4 An optical table 8.5 Economical casting 8.6 Computer-based selection: a manifold jacket

219 220 220 223 227 230 232

Contents

8.7 8.8 9

Computer-based selection: a spark-plug insulator Summary and conclusions

Multiple constraints and objectives 9.1 Introduction and synopsis 9.2 Selection with multiple constraints 9.3 Conflicting objectives, penalty-functions, and exchange constants 9.4 Summary and conclusions 9.5 Further reading Appendix: Traditional methods of dealing with multiple constraints and objectives

vii 235 237 239 240 241 245 254 255 256

10

Case studies — multiple constraints and conflicting objectives 10.1 Introduction and synopsis 10.2 Multiple constraints: con-rods for high-performance engines 10.3 Multiple constraints: windings for high-field magnets 10.4 Conflicting objectives: casings for a mini-disk player 10.5 Conflicting objectives: materials for a disk-brake caliper 10.6 Summary and conclusions

261 262 262 266 272 276 281

11

Selection of material and shape 11.1 Introduction and synopsis 11.2 Shape factors 11.3 Microscopic or micro-structural shape factors 11.4 Limits to shape efficiency 11.5 Exploring and comparing structural sections 11.6 Material indices that include shape 11.7 Co-selecting material and shape 11.8 Summary and conclusions 11.9 Further reading

283 284 285 296 301 305 307 312 314 316

12

Selection of material and shape: case studies 12.1 Introduction and synopsis 12.2 Spars for man-powered planes 12.3 Ultra-efficient springs 12.4 Forks for a racing bicycle 12.5 Floor joists: wood, bamboo or steel? 12.6 Increasing the stiffness of steel sheet 12.7 Table legs again: thin or light? 12.8 Shapes that flex: leaf and strand structures 12.9 Summary and conclusions

317 318 319 322 326 328 331 333 335 337

13

Designing hybrid materials 13.1 Introduction and synopsis 13.2 Filling holes in material-property space 13.3 The method: ‘‘A þ B þ configuration þ scale’’ 13.4 Composites: hybrids of type 1

339 340 342 346 348

viii

Contents

13.5 13.6 13.7 13.8 13.9

Sandwich structures: hybrids of type 2 Lattices: hybrids of type 3 Segmented structures: hybrids of type 4 Summary and conclusions Further reading

358 363 371 376 376

14

Hybrid case studies 14.1 Introduction and synopsis 14.2 Designing metal matrix composites 14.3 Refrigerator walls 14.4 Connectors that do not relax their grip 14.5 Extreme combinations of thermal and electrical conduction 14.6 Materials for microwave-transparent enclosures 14.7 Exploiting anisotropy: heat spreading surfaces 14.8 The mechanical efficiency of natural materials 14.9 Further reading: natural materials

379 380 380 382 384 386 389 391 393 399

15

Information and knowledge sources for design 15.1 Introduction and synopsis 15.2 Information for materials and processes 15.3 Screening information: structure and sources 15.4 Supporting information: structure and sources 15.5 Ways of checking and estimating data 15.6 Summary and conclusions 15.7 Further reading

401 402 403 407 409 411 415 416

16

Materials and the environment 16.1 Introduction and synopsis 16.2 The material life cycle 16.3 Material and energy-consuming systems 16.4 The eco-attributes of materials 16.5 Eco-selection 16.6 Case studies: drink containers and crash barriers 16.7 Summary and conclusions 16.8 Further reading

417 418 418 419 422 427 433 435 436

17

Materials and industrial design 17.1 Introduction and synopsis 17.2 The requirements pyramid 17.3 Product character 17.4 Using materials and processes to create product personality 17.5 Summary and conclusions 17.6 Further reading

439 440 440 442 445 454 455

18

Forces 18.1 18.2 18.3

457 458 458 464

for change Introduction and synopsis Market-pull and science-push Growing population and wealth, and market saturation

Contents

18.4 18.5 18.6 18.7 18.8

Product liability and service provision Miniaturization and multi-functionality Concern for the environment and for the individual Summary and conclusions Further reading

ix 465 466 467 469 469

Appendix A Useful solutions to standard problems Introduction and synopsis A.1 Constitutive equations for mechanical response A.2 Moments of sections A.3 Elastic bending of beams A.4 Failure of beams and panels A.5 Buckling of columns, plates, and shells A.6 Torsion of shafts A.7 Static and spinning disks A.8 Contact stresses A.9 Estimates for stress concentrations A.10 Sharp cracks A.11 Pressure vessels A.12 Vibrating beams, tubes, and disks A.13 Creep and creep fracture A.14 Flow of heat and matter A.15 Solutions for diffusion equations A.16 Further reading

471 473 474 476 478 480 482 484 486 488 490 492 494 496 498 500 502 504

Appendix B Material indices B.1 Introduction and synopsis B.2 Use of material indices

507 508 508

Appendix C.1 C.2 C.3

513 514 515

C.4 C.5 C.6 C.7 C.8 C.9 C.10 C.11 C.12

C Data and information for engineering materials Names and applications: metals and alloys Names and applications: polymers and foams Names and applications: composites, ceramics, glasses, and natural materials Melting temperature, Tm, and glass temperature, Tg Density,
Young’s modulus, E Yield strength, y, and tensile strength, ts Fracture toughness (plane-strain), K1C Thermal conductivity,  Thermal expansion,  Approximate production energies and CO2 burden Environmental resistance

516 518 520 522 524 526 528 530 532 534

x Contents Appendix D.1 D.2 D.3 D.4 D.5 D.6

Appendix E.1 E.2 E.3 E.4 E.5 E.6 E.7 E.8 E.9 Index

D Information and knowledge sources for materials and processes Introduction Information sources for materials Information for manufacturing processes Databases and expert systems in software Additional useful internet sites Supplier registers, government organizations, standards and professional societies

537 538 538 552 553 554

E Exercises Introduction to the exercises Devising concepts Use of material selection charts Translation: constraints and objectives Deriving and using material indices Selecting processes Multiple constraints and objectives Selecting material and shape Hybrid materials

557 558 559 559 562 565 574 579 587 594

555

599

Chapter 1

Introduction 10000BC

5000BC

Relative importance

Gold

0

Copper Bronze Iron

1000 1500 1800

1980

1990

Dual Phase Steels

Glues

Microalloyed Steels New Super Alloys

Light Alloys Rubber

Polymers & elastomers

Super Alloys

Paper Titanium Zirconium etc

Stone Flint Pottery Glass

High Temperature Polymers

Alloys

Ceramic Composites Polyesters Metal-Matrix Epoxies Composites PMMA Acrylics Kelvar-FRP Ceramics & PC PS PP CFRP glasses GFRP Fused Pyro- Tough Engineering Cermets Silica Ceramics Ceramics ( Al2O3, Si3N4, PSZ etc ) Nylon PE

Cement Refractories Portland Cement 1000 1500 1800

1900

1940

1960

1980

1990

2000

DATE

Chapter contents

1.5 1.6

Composites

High Modulus Polymers

Bakerlite