IN
MATERIALS SELECTION
IN
MECHANICAL DESIGN
SECOND EDITION
SECOND EDITION
MICHAEL F. ASH BY
Department of Engineering, Cambridge University, England
MICHAEL F. ASHBY
Department of Engineering, Cambridge University, England
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEWDELHI
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI
,Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Woburn, MA 0 1801-204 1
A division of Reed Educational and Professional Publishing Ltd
-&A member of the Reed Elsevier plc group
First published by Pergamon Press Ltd 1992
Reprinted with corrections 1993
Reprinted 1995, 1996, 1997
Second edition 1999
Reprinted 2000 (twice)
0 Michael F. Ashby 1999
All rights reserved. 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 W 1 P OLP.
Applications for the copyright holder’s written permission
to reproduce any part of this publication should be addressed
to the publishers
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 catalogue record for this book is available from the Library of Congress
ISBN 0 7506 4357 9
Typeset by Laser Words, Madras, India
Printed in Great Britain
,Contents
PREFACE xi
ACKNOWLEDGEMENTS xiii
1 Introduction 1
1.1 Introduction and synopsis 1
1.2 Materials in design 1
1.3 The evolution of engineering materials 3
1.4 The evolution of materials in vacuum cleaners 4
1.5 Summary and conclusions 6
1.6 Further reading 7
2 The design process 8
2.1 Introduction and synopsis 8
2.2 The design process 8
2.3 Types of design 10
2.4 Design tools and materials data 11
2.5 Function, material, shape and process 13
2.6 Devices to open corked bottles 14
2.7 Summary and conclusions 18
2.8 Further reading 19
3 Engineering materials and their properties 20
3. I Introduction and synopsis 20
3.2 The classes of engineering material 20
3.3 The definitions of material properties 22
3.4 Summary and conclusions 31
3.5 Further reading 31
4 Materials selection charts 32
4.1 Introduction and synopsis 32
4.2 Displaying material properties 32
4.3 The material property charts 36
4.4 Summary and conclusions 63
4.5 Further reading 64
, vi Contents
5 Materials selection - the basics 65
5.1 Introduction and synopsis 65
5.2 The selection strategy 65
5.3 Deriving property limits and material indices 69
5.4 The selection procedure 77
5.5 The structural index 82
5.6 Summary and conclusions 83
5.7 Further reading 83
6 Materials selection - case studies 85
6.1 Introduction and synopsis 85
6.2 Materials for oars 85
6.3 Mirrors for large telescopes 89
6.4 Materials for table legs 93
6.5 Cost - structural materials for buildings 97
6.6 Materials for flywheels 100
6.7 Materials for high-flow fans 105
6.8 Golf-ball print heads 108
6.9 Materials for springs 111
6.10 Elastic hinges 116
6.11 Materials for seals 119
6.12 Diaphragms for pressure actuators 122
6.13 Knife edges and pivots 125
6.14 Deflection-limited design with brittle polymers 129
6.15 Safe pressure vessels 133
6.16 Stiff, high damping materials for shaker tables 137
6.17 Insulation for short-term isothermal containers 140
6.18 Energy-efficient kiln walls 143
6.19 Materials for passive solar heating 147
6.20 Materials to minimize thermal distortion in precision devices 151
6.21 Ceramic valves for taps 154
6.22 Nylon bearings for ships’ rudders 157
6.23 Summary and conclusions 160
6.24 Further reading 161
7 Selection of material and shape 162
7.1 Introduction and synopsis 162
7.2 Shape factors 162
7.3 The efficiency of standard sections 172
7.4 Material limits for shape factors 175
7.5 Material indices which include shape 180
7.6 The microscopic or micro-structural shape factor 182
7.7 Co-selecting material and shape 186
7.8 Summary and conclusions 188
7.9 Further reading 190
Appendix: geometric constraints and associated shape factors 190
MATERIALS SELECTION
IN
MECHANICAL DESIGN
SECOND EDITION
SECOND EDITION
MICHAEL F. ASH BY
Department of Engineering, Cambridge University, England
MICHAEL F. ASHBY
Department of Engineering, Cambridge University, England
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEWDELHI
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI
,Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Woburn, MA 0 1801-204 1
A division of Reed Educational and Professional Publishing Ltd
-&A member of the Reed Elsevier plc group
First published by Pergamon Press Ltd 1992
Reprinted with corrections 1993
Reprinted 1995, 1996, 1997
Second edition 1999
Reprinted 2000 (twice)
0 Michael F. Ashby 1999
All rights reserved. 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 W 1 P OLP.
Applications for the copyright holder’s written permission
to reproduce any part of this publication should be addressed
to the publishers
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 catalogue record for this book is available from the Library of Congress
ISBN 0 7506 4357 9
Typeset by Laser Words, Madras, India
Printed in Great Britain
,Contents
PREFACE xi
ACKNOWLEDGEMENTS xiii
1 Introduction 1
1.1 Introduction and synopsis 1
1.2 Materials in design 1
1.3 The evolution of engineering materials 3
1.4 The evolution of materials in vacuum cleaners 4
1.5 Summary and conclusions 6
1.6 Further reading 7
2 The design process 8
2.1 Introduction and synopsis 8
2.2 The design process 8
2.3 Types of design 10
2.4 Design tools and materials data 11
2.5 Function, material, shape and process 13
2.6 Devices to open corked bottles 14
2.7 Summary and conclusions 18
2.8 Further reading 19
3 Engineering materials and their properties 20
3. I Introduction and synopsis 20
3.2 The classes of engineering material 20
3.3 The definitions of material properties 22
3.4 Summary and conclusions 31
3.5 Further reading 31
4 Materials selection charts 32
4.1 Introduction and synopsis 32
4.2 Displaying material properties 32
4.3 The material property charts 36
4.4 Summary and conclusions 63
4.5 Further reading 64
, vi Contents
5 Materials selection - the basics 65
5.1 Introduction and synopsis 65
5.2 The selection strategy 65
5.3 Deriving property limits and material indices 69
5.4 The selection procedure 77
5.5 The structural index 82
5.6 Summary and conclusions 83
5.7 Further reading 83
6 Materials selection - case studies 85
6.1 Introduction and synopsis 85
6.2 Materials for oars 85
6.3 Mirrors for large telescopes 89
6.4 Materials for table legs 93
6.5 Cost - structural materials for buildings 97
6.6 Materials for flywheels 100
6.7 Materials for high-flow fans 105
6.8 Golf-ball print heads 108
6.9 Materials for springs 111
6.10 Elastic hinges 116
6.11 Materials for seals 119
6.12 Diaphragms for pressure actuators 122
6.13 Knife edges and pivots 125
6.14 Deflection-limited design with brittle polymers 129
6.15 Safe pressure vessels 133
6.16 Stiff, high damping materials for shaker tables 137
6.17 Insulation for short-term isothermal containers 140
6.18 Energy-efficient kiln walls 143
6.19 Materials for passive solar heating 147
6.20 Materials to minimize thermal distortion in precision devices 151
6.21 Ceramic valves for taps 154
6.22 Nylon bearings for ships’ rudders 157
6.23 Summary and conclusions 160
6.24 Further reading 161
7 Selection of material and shape 162
7.1 Introduction and synopsis 162
7.2 Shape factors 162
7.3 The efficiency of standard sections 172
7.4 Material limits for shape factors 175
7.5 Material indices which include shape 180
7.6 The microscopic or micro-structural shape factor 182
7.7 Co-selecting material and shape 186
7.8 Summary and conclusions 188
7.9 Further reading 190
Appendix: geometric constraints and associated shape factors 190
