Fatigue assessment of welded joints by local approaches Related titles: Cumulative damage of welded joints (ISBN-13: 978-1-85573-938-3; ISBN-10: 1-85573-938-0) Written by one of the leading experts in the field, Dr Tim Gurney, this important book examines fatigue in welded joints, both as a result of constant loads and variable amplitude loading Fatigue strength of welded structures Third edition (ISBN-13: 978-1-85573-506-4; ISBN-10: 1-85573-506-7) Research on the fatigue behaviour of welded structures has improved our understanding of the design methods that can reduce premature or progressive fatigue cracking The latest edition of this standard text incorporates recent research on understanding and preventing fatigue-related failure through good design Fatigue analysis of welded components: designer’s guide to the structural hot-spot stress approach (ISBN-13: 978-184569-124-0; ISBN-10: 1-84569-124-5) This report from the International Institute of Welding provides practical guidance on the use of the hot-spot stress approach to improve both the fatigue analysis and design of welded structures Details of these and other Woodhead Publishing materials books and journals, as well as materials books from Maney Publishing, can be obtained by: • visiting www.woodheadpublishing.com • contacting Customer Services (e-mail: sales@woodhead-publishing.com; fax: +44 (0) 1223 893694; tel.: +44 (0) 1223 891358 ext 30; address: Woodhead Publishing Ltd, Abington Hall, Abington, Cambridge CB1 6AH, England) Maney currently publishes 16 peer-reviewed materials science and engineering journals For further information visit www.maney.co.uk/journals Fatigue assessment of welded joints by local approaches Second edition D Radaj, C M Sonsino and W Fricke Woodhead Publishing and Maney Publishing on behalf of The Institute of Materials, Minerals & Mining CRC Press Boca Raton Boston New York Washington, DC Cambridge England Woodhead Publishing Limited and Maney Publishing Limited on behalf of The Institute of Materials, Minerals & Mining Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB1 6AH, England www.woodheadpublishing.com Published in North America by CRC Press LLC, 6000 Broken Sound Parkway, NW, Suite 300, Boca Raton, FL 33487, USA First published 1998 by Abington Publishing, an imprint of Woodhead Publishing Limited Second edition 2006, Woodhead Publishing Limited and CRC Press LLC © Woodhead Publishing Limited, 2006 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 publishers cannot assume responsibility for the validity of all materials Neither the authors nor the publishers, 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 Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress Woodhead Publishing ISBN-13: 978-1-85573-948-2 (book) Woodhead Publishing ISBN-10: 1-85573-948-8 (book) Woodhead Publishing ISBN-13: 978-1-84569-188-2 (e-book) Woodhead Publishing ISBN-10: 1-84569-188-1 (e-book) CRC Press ISBN-13: 978-0-8493-8451-6 CRC Press ISBN-10: 0-8493-8451-6 CRC Press order number: WP8451 The publishers’ 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 elementary chlorine-free practices Furthermore, the publishers ensure that the text paper and cover board used have met acceptable environmental accreditation standards Typeset by SNP Best-set Typesetter Ltd., Hong Kong Printed by TJ International Limited, Padstow, Cornwall, England Contents Foreword Preface Author contact details Introduction 1.1 1 1.2 xv xvii xix Fatigue strength assessment of welded joints 1.1.1 Present state of the art 1.1.2 Demands from industrial product development Basic aspects of assessment procedures 1.2.1 Multitude of parameters governing fatigue failure 1.2.2 Global and local approaches of fatigue strength assessment 1.2.3 Complications of local approaches for welded joints 1.2.4 Survey of subject arrangement 3 10 Nominal stress approach for welded joints 13 2.1 13 13 13 16 2.2 Basic procedures 2.1.1 Principles of the nominal stress approach 2.1.2 Procedures for welded joints Analysis tools 2.2.1 Books, compendia, guidelines and design codes 2.2.2 Basic formulae 2.2.3 Permissible stresses and design S–N curves 2.2.4 Influence of mean and residual stresses 2.2.5 Influence of stress multiaxiality 2.2.6 Influence of plate thickness, weld dressing and environment 16 16 19 23 24 27 v vi Contents 2.2.7 2.2.8 Normalised S–N curves Fatigue strength reduction factors 28 29 Structural stress or strain approach for seam-welded joints 33 3.1 33 3.2 3.3 Basic procedures 3.1.1 Principles of the structural stress or strain approach 3.1.2 Structural strain approach as proposed by Haibach 3.1.3 Hot spot structural stress approach for tubular joints 3.1.4 Hot spot structural stress approach for non-tubular joints 3.1.5 Alternative definitions of hot spot structural stress 3.1.6 Structural stress approach as proposed by Dong 3.1.7 Structural stress approach as proposed by Xiao–Yamada 3.1.8 Structural stress approach to weld root fatigue Analysis tools – structural stress or strain evaluation 3.2.1 General survey and relevant guidelines 3.2.2 Evaluation of hot spot stresses in tubular joints 3.2.3 Evaluation of hot spot stresses in non-tubular joints 3.2.4 Specific rules for finite element modelling 3.2.5 Further variants of structural stress evaluation 3.2.6 Definition of structural stress concentration factors 3.2.7 Hot spot stress concentration factors for tubular joints 3.2.8 Hot spot stress concentration factors for non-tubular joints Analysis tools – endurable structural stresses or strains 3.3.1 Endurable structural strains in the Haibach approach 33 34 37 40 40 41 43 44 45 45 46 48 51 55 57 59 61 62 62 Contents 3.3.2 3.3.3 3.4 Endurable hot spot stresses in tubular joints Endurable hot spot stresses in non-tubular joints 3.3.4 Endurable structural stresses in the Dong and Xiao–Yamada approaches 3.3.5 Endurable multiaxial stresses or strains 3.3.6 Structural stress based assessment of weld root fatigue Demonstration examples 3.4.1 Welded tubular and butt joints – structural strain approach 3.4.2 Welded tubular joints – various design guidelines 3.4.3 Welded bridge girder with cope holes 3.4.4 Welded joints in ship structures – weld toe fatigue 3.4.5 Welded joints in ship structures – weld root fatigue vii 62 65 68 70 73 81 81 82 84 84 89 Notch stress approach for seam-welded joints 91 4.1 91 4.2 Basic procedures 4.1.1 Principles and variants of the notch stress approach 4.1.2 Critical distance approach 4.1.3 Fictitious notch rounding approach 4.1.4 Modified notch rounding approach 4.1.5 Highly stressed volume approach Analysis tools 4.2.1 General survey and assessment procedure 4.2.2 Notch stress analysis for welded joints 4.2.3 Notch stress concentration factors of welded joints 4.2.4 Fatigue notch factors of welded joints 4.2.5 Critical distance approach 4.2.6 Fictitious notch rounding approach – basic procedures 4.2.7 Fictitious notch rounding approach – refined procedures 4.2.8 Fictitious notch rounding approach – links to structural stresses 4.2.9 Modified notch rounding approach 4.2.10 Highly stressed volume approach 91 94 96 101 105 105 105 107 108 121 125 126 131 138 143 145 viii Contents 4.3 4.4 150 150 152 155 157 158 160 161 163 165 166 166 173 180 186 Notch strain approach for seam-welded joints 191 5.1 191 191 195 199 202 202 202 206 212 213 214 5.2 5.3 Demonstration examples 4.3.1 Welded vehicle frame corner 4.3.2 Web stiffener of welded I section girder 4.3.3 Stress relief groove in welded pressure vessel 4.3.4 End-to-shell joint of boiler 4.3.5 Stiffener-to-flange joint at ship frame corner 4.3.6 Girth butt welds of unusual manufacture 4.3.7 Tensile specimen with longitudinal attachment 4.3.8 Gusseted shell structure 4.3.9 Laser beam welded butt and cruciform joints Design-related notch stress evaluations 4.4.1 Comparison of basic welded joint types 4.4.2 Comparison of basic weld loading modes 4.4.3 Effect of geometrical weld parameters 4.4.4 Typical application in design Basic procedures 5.1.1 Principles of the notch strain approach 5.1.2 Early application of the approach 5.1.3 Comprehensive exposition of the approach 5.1.4 Further refinements of the approach Analysis tools 5.2.1 Basic formulae in early applications 5.2.2 Basic formulae for wider application 5.2.3 Special formulae for multiaxial fatigue 5.2.4 Assessment procedure Demonstration examples 5.3.1 Fatigue life of stress-relieved butt-welded joints 5.3.2 Fatigue life of butt-welded joints with residual stresses 5.3.3 Fatigue life of fillet-welded cruciform joints 5.3.4 Fatigue life of welded containment detail 5.3.5 Fatigue strength of welded tubular joint 214 217 221 224 227 Crack propagation approach for seam-welded joints 233 6.1 233 233 235 237 240 Basic procedures 6.1.1 Principles of the crack propagation approach 6.1.2 Peculiarities with seam-welded joints 6.1.3 Short-crack behaviour 6.1.4 Applications of the approach Contents 6.2 6.3 Analysis tools 6.2.1 General survey and relevant references 6.2.2 Methods of stress intensity factor determination 6.2.3 Crack propagation equations 6.2.4 Crack propagation life 6.2.5 Stress intensity factors for welded joints 6.2.6 Crack shape and crack path 6.2.7 Material parameters of crack propagation 6.2.8 Initial and final crack size 6.2.9 Residual stress effects on crack propagation 6.2.10 Particular crack propagation approach 6.2.11 Refined crack propagation approach Demonstration examples 6.3.1 Longitudinal and transverse attachment joints 6.3.2 Cruciform and T-joints 6.3.3 Lap joints and cover plate joints 6.3.4 Butt-welded joints 6.3.5 Refined analysis of longitudinal attachment joint ix 242 242 243 245 247 250 259 263 267 268 271 275 279 279 281 286 287 292 Notch stress intensity approach for seam-welded joints 296 7.1 7.2 7.3 General considerations 7.1.1 Formal aspects of presentation 7.1.2 Principles and variants of the approach Basic procedures and results 7.2.1 Notch stress intensity at sharp corner notches 7.2.2 Notch stress intensity at blunt corner notches 7.2.3 Plastic notch stress intensity at corner notches 7.2.4 J-integral at corner notches 7.2.5 Strain energy density at corner notches 7.2.6 Fatigue limit expressed by notch stress intensity factors Procedures and results for fillet-welded joints 7.3.1 Notch stress intensity factors for fillet-welded joints 7.3.2 Stress rise in front of fillet welds 7.3.3 Endurable notch stress intensity factors of fillet-welded joints 296 296 296 297 297 301 304 307 308 310 313 313 317 319 ... publication of the first edition of Fatigue assessment of welded joints by local approaches substantial progress has been achieved in methods development and application of local approaches Structural... respect of user demands, and the local parameter data, for the most part, lack Fatigue assessment of welded joints by local approaches statistical proof As a result, the application of local approaches. . .Fatigue assessment of welded joints by local approaches Related titles: Cumulative damage of welded joints (ISBN-13: 978-1-85573-938-3; ISBN-10: 1-85573-938-0) Written by one of the leading