Fracture and fatigue of welded joints and structures © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 1 3/23/11 1:52:28 PM Related titles: Fatigue assessment of welded joints by local approaches: Second edition (ISBN 978-1-85573-948-2) Local approaches to fatigue assessment are used to predict the structural durability of welded joints, to optimise their design and to evaluate unforeseen joint failures. This completely reworked second edition of a standard work provides a systematic survey of the principles and practical applications of the various methods. It covers the hot spot structural stress approach to fatigue in general, the notch stress and notch strain approach to crack initiation and the fracture mechanics approach to crack propagation. Seam-welded and spot-welded joints in structural steels and aluminium alloys are also considered. Failure mechanisms of advanced welding processes (ISBN 978-1-84569-536-1) Many new, or relatively new, welding processes such as friction stir welding, resistance spot welding and laser welding are being increasingly adopted by companies to replace or improve on traditional welding techniques. Improvements in welding speed and ease of automation are often used as reasons for choosing advanced welding processes. Before advanced techniques are employed, their potential failure mechanisms should be well understood and their suitability for welding particular metals and alloys in different situations should be assessed. This important book will provide a critical analysis of advanced welding techniques and their potential failure mechanisms. Friction stir welding: from basics to applications (ISBN 978-1-84569-450-0) Friction stir welding (FSW) is a solid-state welding process that is gaining wide acceptance in industry, especially the shipbuilding, aerospace, mass transportation and automotive industries. FSW is particularly suited to those industries that use aluminium and its alloys. This authoritative book provides a comprehensive review of the subject of friction stir welding and covers topics such as process basics, equipment, modelling, inspection and quality control and applications. Details of these and other Woodhead Publishing materials books can be obtained by:  visiting our web site at www.woodheadpublishing.com  contacting Customer Services (e-mail: [email protected]; fax: +44 (0) 1223 832819; tel.: +44 (0) 1223 499140; address: Woodhead Publishing Limited, 80 High Street, Sawston, Cambridge CB22 3HJ, UK) If you would like to receive information on forthcoming titles, please send your address details to: Francis Dodds (address, tel. and fax as above; e-mail: francis.dodds@ woodheadpublishing.com). Please confirm which subject areas you are interested in. © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 2 3/23/11 1:52:28 PM Fracture and fatigue of welded joints and structures Edited by Kenneth A. Macdonald Oxford Cambridge Philadelphia New Delhi © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 3 3/23/11 1:52:28 PM Published by Woodhead Publishing Limited, 80 High Street, Sawston, Cambridge CB22 3HJ, UK www.woodheadpublishing.com Woodhead Publishing, 1518 Walnut Street, Suite 1100, Philadelphia, PA 19102-3406, USA Woodhead Publishing India Private Limited, G-2, Vardaan House, 7/28 Ansari Road, Daryaganj, New Delhi – 110002, India www.woodheadpublishingindia.com First published 2011, Woodhead Publishing Limited © Woodhead Publishing Limited, 2011 The authors have asserted their moral rights. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish reliable data and information, but the authors and the publisher cannot assume responsibility for the validity of all materials. Neither the authors nor the publisher, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming and recording, or by any information storage or retrieval system, without permission in writing from Woodhead Publishing Limited. The consent of Woodhead Publishing Limited does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from Woodhead Publishing Limited for such copying. 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. ISBN 978-1-84569-513-2 (print) ISBN 978-0-85709-250-2 (online) The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp which is processed using acid- free and elemental chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met acceptable environmental accreditation standards. Typeset by Replika Press Pvt Ltd, India Printed by TJI Digital, Padstow, Cornwall, UK © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 4 3/23/11 1:52:28 PM Contents Contributor contact details ix Preface xiii Introduction 1 K. A. Macdonald, University of Stavanger, Norway Part I Analysing fracture of welded joints and structures 1 Constraint-based fracture mechanics in predicting the failure of welded joints 17 n. o’dowd, University of Limerick, Ireland 1.1 Introduction to constraint-based elastic-plastic fracture mechanics 17 1.2 Constraint parameters 18 1.3 Tabulation of Q-solutions 22 1.4 Development of a failure assessment diagram (FAD) approach to incorporate constraint 25 1.5 Effect of weld mismatch on crack tip constraint 27 1.6 Full field (local approach) analysis for fracture assessment 28 1.7 Conclusion 28 1.8 References 28 2 Constraint fracture mechanics: test methods 31 K. a. Macdonald, University of Stavanger, Norway, E. Østby and B. Nyhus, SINTEF Materials and Chemistry, Norway 2.1 Introduction 31 2.2 High strains 32 2.3 Two-parameter fracture mechanics 35 2.4 Development of the single edge notch tension (SENT) test 36 © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 5 3/23/11 1:52:28 PM vvii Contents 2.5 Standardising the single edge notch tension (SENT) test 51 2.6 Conclusions 54 2.7 References 55 2.8 Appendix: Codes and standards 57 2.9 Nomenclature 58 3 Fracture assessment methods for welded structures 60 I. hadlEy, TWI, UK 3.1 Introduction 60 3.2 Development of engineering critical assessment (ECA) methods 63 3.3 The failure assessment diagram (FAD) concept 64 3.4 Specific engineering critical assessment (ECA) methods: R6 67 3.5 Specific engineering critical assessment (ECA) methods: BS 7910/PD6493 72 3.6 Specific engineering critical assessment (ECA) methods: Structural Integrity Procedures for European Industry (SINTAP)/European Fitness-for-Service Network (FITNET) 81 3.7 Specific engineering critical assessment (ECA) methods: American Petroleum Institute (API)/American Society of Mechanical Engineers (ASME) 85 3.8 Future trends 87 3.9 References 88 4 The use of fracture mechanics in the fatigue analysis of welded joints 91 a. hobbachEr, University of Applied Sciences Wilhelmshaven, Germany 4.1 Introduction to fracture mechanics 91 4.2 Technical applications of fracture mechanics 93 4.3 Fatigue assessment of welded joints using fracture mechanics 97 4.4 Examples of practical application 107 4.5 Conclusions 110 4.6 References 111 Part II Analysing fatigue of welded joints and structures 5 Fatigue strength assessment of local stresses in welded joints 115 w. FrIcKE, Hamburg University of Technology, Germany 5.1 Introduction 115 © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 6 3/23/11 1:52:28 PM Contents vviiii 5.2 Types of stress 117 5.3 Factors affecting the fatigue strength 124 5.4 Fatigue strength assessment 129 5.5 Conclusions 137 5.6 References 137 6 Improving weld class systems in assessing the fatigue life of different welded joint designs 139 b. Jonsson, Volvo Construction Equipment, Sweden 6.1 Introduction 139 6.2 Historic view 140 6.3 Weld class system ISO 5817 142 6.4 Weld class systems at Volvo 143 6.5 A consistent and objective weld class system 144 6.6 Discussion 162 6.7 Conclusions 163 6.8 Future trends 164 6.9 Source of further information and advice 166 6.10 References 166 7 Fatigue design rules for welded structures 168 s. J. Maddox, formerly at TWI, UK 7.1 Introduction 168 7.2 Key features of welded joints influencing fatigue 170 7.3 Fatigue crack propagation 175 7.4 Design rules 177 7.5 Future developments in the application of fatigue rules 189 7.6 Conclusions 202 7.7 References 203 7.8 Appendix: fatigue design codes and standards 206 8 Fatigue assessment methods for variable amplitude loading of welded structures 208 G. b. MarquIs, Aalto University, Finland 8.1 Introduction 208 8.2 Fatigue damage and assessment for variable amplitude loading 214 8.3 Variable amplitude fatigue testing 226 8.4 Future trends 233 8.5 Sources of further information and advice 234 8.6 References and further reading 235 © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 7 3/23/11 1:52:29 PM vviiiiii Contents 9 Reliability apects in fatigue design of welded structures using selected local approaches: the example of k-nodes for offshore constructions 239 c. M. sonsIno, Fraunhofer Institute for Structural Durability and System Reliability LBF, Germany 9.1 Introduction 239 9.2 Selected decisive design parameters 239 9.3 Selected design concepts by the example of K-nodes 261 9.4 Conclusions 273 9.5 References 274 10 Assessing residual stresses in predicting the service life of welded structures 276 M. n. JaMEs, University of Plymouth, UK, d. G. hattInGh and w. h. rall, Nelson Mandela Metropolitan University, South Africa and a. stEuwEr, ESS Scandinavia, Sweden 10.1 Introduction 276 10.2 Origins and types of stress 278 10.3 Modification of stresses after welding 283 10.4 Measurement 285 10.5 Conclusions 292 10.6 Acknowledgements 293 10.7 References 293 11 Fatigue strength improvement methods 297 P. J. haaGEnsEn, Norwegian University of Science and Technology (NTNU), Norway 11.1 Introduction 297 11.2 Fatigue strength of welded joints 298 11.3 Increasing the fatigue strength by improved design 301 11.4 Improvements obtained by special plate, filler materials and welding methods 305 11.5 Special welding methods 307 11.6 Post-weld improvement methods 307 11.7 Future trends 324 11.8 Conclusions 327 11.9 References and further reading 327 Index 331 © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 8 3/23/11 1:52:29 PM Contributor contact details (* = main contact) Editor Chapter 2 K. A. Macdonald K. A. Macdonald* University of Stavanger University of Stavanger Department of Mechanical and Department of Mechanical and Structural Engineering and Structural Engineering and Materials Science Materials Science N-4036 Stavanger N-4036 Stavanger Norway Norway E-mail: [email protected] E-mail: [email protected] E. Østby and B. Nyhus Chapter 1 SINTEF Materials and Chemistry Professor Noel O’Dowd Department of Applied Mechanics Department of Mechanical and and Corrosion Aeronautical Engineering N-7465 Trondheim Materials and Surface Science Norway Institute University of Limerick Chapter 3 Ireland I. Hadley E-mail: [email protected] TWI Abington Hall Granta Park Great Abington Cambridge CB21 6AL UK E-mail: [email protected] © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 9 3/23/11 1:52:29 PM xx Contributor contact details Chapter 4 Chapter 8 A. Hobbacher Professor G. B. Marquis University of Applied Sciences Aalto University Wilhelmshaven Department of Applied Mechanics Germany P.O. Box 14300 FI-00076 Aalto E-mail: [email protected] Finland E-mail: [email protected] Chapter 5 W. Fricke Chapter 9 Ship Structural Design and Analysis C. M. Sonsino Hamburg University of Technology Fraunhofer Institute for Structural (TUHH) Durability and System Schwarzenbergstr. 95c Reliability LBF 21073 Hamburg Bartningstr. 47 Germany D-64289 Darmstadt Germany E-mail: [email protected] E-mail: [email protected] Chapter 6 Chapter 10 B. Jonsson Volvo Construction Equipment M. N. James* HL Division School of Engineering 360 42 Braås University of Plymouth Sweden Drake Circus Plymouth PL4 8AA E-mail: [email protected] UK E-mail: [email protected] Chapter 7 S. J. Maddox D. G. Hattingh and W. H. Rall TWI Mechanical Engineering Granta Park Nelson Mandela Metropolitan Great Abington University Cambridge CB21 6AL Gardham Avenue UK Box 77000 Port Elizabeth 6031 E-mail: [email protected] South Africa © Woodhead Publishing Limited, 2011 Welded-Mcdonald-Pre.indd 10 3/23/11 1:52:29 PM