IIW Recommendations On Methods for Improving the Fatigue Strength of Welded Joints
IIW Recommendations On Methods for Improving the Fatigue Strength of Welded Joints

Author: P J Haagensen

Publisher: Woodhead Publishing

Published: 2013-01-25

Total Pages: 90

ISBN-13: 1782420657

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The weld toe is a primary source of fatigue cracking because of the severity of the stress concentration it produces. Weld toe improvement can increase the fatigue strength of new structures significantly. It can also be used to repair or upgrade existing structures. However, in practice there have been wide variations in the actual improvements in fatigue strength achieved. Based on an extensive testing programme organised by the IIW, this report reviews the main methods for weld toe improvement to increase fatigue strength: burr grinding, TIG dressing and hammer and needle peening. The report provides specifications for the practical use of each method, including equipment, weld preparation and operation. It also offers guidance on inspection, quality control and training as well as assessments of fatigue strength and thickness effects possible with each technique. IIW recommendations on methods for improving the fatigue strength of welded joints will allow a more consistent use of these methods and more predictable increases in fatigue strength. Provides specifications for the practical use of each weld toe method, including equipment, weld preparation and operation Offers guidance on inspection, quality control and training, as well as assessments of fatigue strength and thickness effects possible with each technique This report will allow a more consistent use of these methods and more predictable increases in fatigue strength

IIW Recommendations for the HFMI Treatment
IIW Recommendations for the HFMI Treatment

Author: Gary B. Marquis

Publisher: Springer

Published: 2016-09-29

Total Pages: 44

ISBN-13: 9811025045

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This book of recommendations presents an overview of High Frequency Mechanical Impact (HFMI) techniques existing today in the market and their proper procedures, quality assurance measures and documentation. Due to differences in HFMI tools and the wide variety of potential applications, certain details of proper treatments and quantitative quality control measures are presented generally. An example of procedure specification as a quality assurance measure is given in the Appendix. Moreover, the book presents procedures for the fatigue life assessment of HFMI-improved welded joints based on nominal stress, structural hot spot stress and effective notch stress. It also considers the extra benefit that has been experimentally observed for HFMI-treated high-strength steels. The recommendations offer proposals on the effect of loading conditions like high mean stress fatigue cycles, variable amplitude loading and large amplitude/low cycle fatigue cycles. Special considerations for low stress concentration welded joints are also given. In order to demonstrate the use of the guideline, the book provides several fatigue assessment examples.

Fracture and Fatigue of Welded Joints and Structures
Fracture and Fatigue of Welded Joints and Structures

Author: K Macdonald

Publisher: Elsevier

Published: 2011-04-19

Total Pages: 353

ISBN-13: 0857092502

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The failure of any welded joint is at best inconvenient and at worst can lead to catastrophic accidents. Fracture and fatigue of welded joints and structures analyses the processes and causes of fracture and fatigue, focusing on how the failure of welded joints and structures can be predicted and minimised in the design process.Part one concentrates on analysing fracture of welded joints and structures, with chapters on constraint-based fracture mechanics for predicting joint failure, fracture assessment methods and the use of fracture mechanics in the fatigue analysis of welded joints. In part two, the emphasis shifts to fatigue, and chapters focus on a variety of aspects of fatigue analysis including assessment of local stresses in welded joints, fatigue design rules for welded structures, k-nodes for offshore structures and modelling residual stresses in predicting the service life of structures.With its distinguished editor and international team of contributors, Fracture and fatigue of welded joints and structures is an essential reference for mechanical, structural and welding engineers, as well as those in the academic sector with a research interest in the field. - Analyses the processes and causes of fracture and fatigue, focusing predicting and minimising the failure of welded joints in the design process - Assesses the fracture of welded joints and structure featuring constraint-based fracture mechanics for predicting joint failure - Explores specific considerations in fatigue analysis including the assessment of local stresses in welded joints and fatigue design rules for welded structures

Fatigue Assessment of Welded Joints by Local Approaches
Fatigue Assessment of Welded Joints by Local Approaches

Author: Dieter Radaj

Publisher: Woodhead Publishing

Published: 2006-10-30

Total Pages: 661

ISBN-13: 1845691881

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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 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.This completely reworked second edition takes into account the tremendous progress in understanding and applying local approaches which has been achieved in the last decade. It is a standard reference for designers, structural analysts and testing engineers who are responsible for the fatigue-resistant in-service behaviour of welded structures. - Completely reworked second edition of a standard work providing a systematic survey of the principles and practical applications of the various methods - 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. - Written by a distinguished team of authors

IIW Guidelines on Weld Quality in Relationship to Fatigue Strength
IIW Guidelines on Weld Quality in Relationship to Fatigue Strength

Author: Bertil Jonsson

Publisher: Springer

Published: 2016-04-13

Total Pages: 124

ISBN-13: 3319191985

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This book presents guidelines on quantitative and qualitative measures of the geometric features and imperfections of welds to ensure that it meets the fatigue strength requirements laid out in the recommendations of the IIW (International Institute of Welding). Welds that satisfy these quality criteria can be assessed in accordance with existing IIW recommendations based on nominal stress, structural stress, notch stress or linear fracture mechanics. Further, the book defines more restrictive acceptance criteria based on weld geometry features and imperfections with increased fatigue strength. Fatigue strength for these welds is defined as S-N curves expressed in terms of nominal applied stress or hot spot stress. Where appropriate, reference is made to existing quality systems for welds.In addition to the acceptance criteria and fatigue assessment curves, the book also provides guidance on their inspection and quality control. The successful implementation of these methods depends on adequate training for operators and inspectors alike. As such, the publication of the present IIW Recommendations is intended to encourage the production of appropriate training aids and guidelines for educating, training and certifying operators and inspectors.

Recommendations for Fatigue Design of Welded Joints and Components
Recommendations for Fatigue Design of Welded Joints and Components

Author: A. F. Hobbacher

Publisher: Springer

Published: 2015-12-23

Total Pages: 153

ISBN-13: 3319237578

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This book provides a basis for the design and analysis of welded components that are subjected to fluctuating forces, to avoid failure by fatigue. It is also a valuable resource for those on boards or commissions who are establishing fatigue design codes. For maximum benefit, readers should already have a working knowledge of the basics of fatigue and fracture mechanics. The purpose of designing a structure taking into consideration the limit state for fatigue damage is to ensure that the performance is satisfactory during the design life and that the survival probability is acceptable. The latter is achieved by the use of appropriate partial safety factors. This document has been prepared as the result of an initiative by Commissions XIII and XV of the International Institute of Welding (IIW).

The Theory of Critical Distances
The Theory of Critical Distances

Author: David Taylor

Publisher: Elsevier

Published: 2010-07-07

Total Pages: 307

ISBN-13: 0080554725

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Critical distance methods are extremely useful for predicting fracture and fatigue in engineering components. They also represent an important development in the theory of fracture mechanics. Despite being in use for over fifty years in some fields, there has never been a book about these methods – until now. So why now? Because the increasing use of computer-aided stress analysis (by FEA and other techniques) has made these methods extremely easy to use in practical situations. This is turn has prompted researchers to re-examine the underlying theory with renewed interest. The Theory of Critical Distances begins with a general introduction to the phenomena of mechanical failure in materials: a basic understanding of solid mechanics and materials engineering is assumed, though appropriate introductory references are provided where necessary. After a simple explanation of how to use critical distance methods, and a more detailed exposition of the methods including their history and classification, the book continues by showing examples of how critical distance approaches can be applied to predict fracture and fatigue in different classes of materials. Subsequent chapters include some more complex theoretical areas, such as multiaxial loading and contact problems, and a range of practical examples using case studies of real engineering components taken from the author's own consultancy work. The Theory of Critical Distances will be of interest to a range of readers, from academic researchers concerned with the theoretical basis of the subject, to industrial engineers who wish to incorporate the method into modern computer-aided design and analysis. - Comprehensive collection of published data, plus new data from the author's own laboratories - A simple 'how-to-do-it' exposition of the method, plus examples and case studies - Detailed theoretical treatment - Covers all classes of materials: metals, polymers, ceramics and composites - Includes fracture, fatigue, fretting, size effects and multiaxial loading

Fatigue Life Analyses of Welded Structures
Fatigue Life Analyses of Welded Structures

Author: Tom Lassen

Publisher: John Wiley & Sons

Published: 2013-03-01

Total Pages: 442

ISBN-13: 1118614704

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Avoiding or controlling fatigue damage is a major issue in the design and inspection of welded structures subjected to dynamic loading. Life predictions are usually used for safe life analysis, i.e. for verifying that it is very unlikely that fatigue damage will occur during the target service life of a structure. Damage tolerance analysis is used for predicting the behavior of a fatigue crack and for planning of in-service scheduled inspections. It should be a high probability that any cracks appearing are detected and repaired before they become critical. In both safe life analysis and the damage tolerance analysis there may be large uncertainties involved that have to be treated in a logical and consistent manner by stochastic modeling. This book focuses on fatigue life predictions and damage tolerance analysis of welded joints and is divided into three parts. The first part outlines the common practice used for safe life and damage tolerance analysis with reference to rules and regulations. The second part emphasises stochastic modeling and decision-making under uncertainty, while the final part is devoted to recent advances within fatigue research on welded joints. Industrial examples that are included are mainly dealing with offshore steel structures. Spreadsheets which accompany the book give the reader the possibility for hands-on experience of fatigue life predictions, crack growth analysis and inspection planning. As such, these different areas will be of use to engineers and researchers.

IIW Recommendations for the Fatigue Assessment of Welded Structures By Notch Stress Analysis
IIW Recommendations for the Fatigue Assessment of Welded Structures By Notch Stress Analysis

Author: W Fricke

Publisher: Woodhead Publishing

Published: 2012-10-22

Total Pages: 76

ISBN-13: 085709856X

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The notch stress approach for fatigue assessment of welded joints is based on the highest elastic stress at the weld toe or root. In order to avoid arbitrary or infinite stress results, a rounded shape with a reference radius instead of the actual sharp toe or root is usually assumed. IIW recommendations for the fatigue assessment of welded structures by notch stress analysis reviews different proposals for reference radii together with associated S-N curves. Detailed recommendations are given for the numerical analysis of notch stress by the finite or boundary element method. Several aspects are discussed, such as the structural weakening by keyhole-shaped notches and the consideration of multiaxial stress states. Appropriate S-N curves are presented for the assessment of the fatigue strength of different materials. Finally, four examples illustrate the application of the approach as well as the variety of structures which can be analysed and the range of results that can be obtained from different models. Provides detailed recommendations for the number analysis of notch stress by the finite or boundary element method Discusses structural weakening by keyhole-shaped notches and the consideration of multiaxial stress states Provides four comprehensive examples, illustrating the variety of structures which can be analysed and the range of results that can be obtained from different models