Advanced Methods of Fatigue Assessment

Author: Dieter Radaj
Publisher: Springer Science & Business Media
ISBN: 364230740X
Format: PDF, Docs
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In five chapters, this volume presents recent developments in fatigue assessment. In the first chapter, a generalized Neuber concept of fictitious notch rounding is presented where the microstructural support factors depend on the notch opening angle besides the loading mode. The second chapter specifies the notch stress factor including the strain energy density and J-integral concept while the SED approach is applied to common fillet welded joints and to thin-sheet lap welded joints in the third chapter. The forth chapter analyses elastic-plastic deformations in the near crack tip zone and discusses driving force parameters. The last chapter discusses thermomechanical fatigue, stress, and strain ranges.

Fatigue Testing and Analysis

Author: Yung-Li Lee
Publisher: Elsevier
ISBN: 0080477690
Format: PDF
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Fatigue Testing and Analysis: Theory and Practice presents the latest, proven techniques for fatigue data acquisition, data analysis, and test planning and practice. More specifically, it covers the most comprehensive methods to capture the component load, to characterize the scatter of product fatigue resistance and loading, to perform the fatigue damage assessment of a product, and to develop an accelerated life test plan for reliability target demonstration. This book is most useful for test and design engineers in the ground vehicle industry. Fatigue Testing and Analysis introduces the methods to account for variability of loads and statistical fatigue properties that are useful for further probabilistic fatigue analysis. The text incorporates and demonstrates approaches that account for randomness of loading and materials, and covers the applications and demonstrations of both linear and double-linear damage rules. The reader will benefit from summaries of load transducer designs and data acquisition techniques, applications of both linear and non-linear damage rules and methods, and techniques to determine the statistical fatigue properties for the nominal stress-life and the local strain-life methods. Covers the useful techniques for component load measurement and data acquisition, fatigue properties determination, fatigue analysis, and accelerated life test criteria development, and, most importantly, test plans for reliability demonstrations Written from a practical point of view, based on the authors' industrial and academic experience in automotive engineering design Extensive practical examples are used to illustrate the main concepts in all chapters

Fatigue Assessment of Welded Joints by Local Approaches

Author: Dieter Radaj
Publisher: Woodhead Publishing
ISBN: 9781855734036
Format: PDF, Docs
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This book reviews the available knowledge on local approaches to fatigue assessment of welded joints, gathers the data necessary for their practical application and demonstrates the power of the local concept by way of demonstration examples from research and industry. 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 considered. The book is intended for designers, structural analysts and testing engineers who are responsible for the fatigue-resistant in-service behaviour of welded structures. It should become a reference work for researchers in the field and should support activities directed to standardisation of local approaches.

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

Author: W Fricke
Publisher: Woodhead Publishing
ISBN: 085709856X
Format: PDF, ePub, Docs
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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

Fracture and Fatigue of Welded Joints and Structures

Author: K Macdonald
Publisher: Elsevier
ISBN: 0857092502
Format: PDF, ePub, Mobi
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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

NDT Methods Applied to Fatigue Reliability Assessment of Structures

Author: Jamshid Mohammadi
Publisher: ASCE Publications
ISBN: 9780784407424
Format: PDF, Kindle
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Sponsored by the Fatigue and Fracture Reliability Committee of the Structural Engineering Institute of ASCE. This report contains nine specific-application cases of various nondestructive test (NDT) methods in fatigue and fracture reliability assessment of structures. The collection is useful in learning about areas where current methods have actually been applied in real world applications. Cases examine problems such as steel girder bridges, airframe systems, welded connections, and bridge components (including concrete slabs), which were subjected to fracture failure. The report includes such NDT methods as: structural monitoring; use of various methods for the identification of the extent of damage; acoustic emissions technique; electromagnetic; portable hardness test; liquid penetrant; magnetic particle; radiography; residual stress by hole drill; and ultrasonic methods. The fatigue reliability assessment methods discussed in this book will be especially useful to practitioners, educators, and students in structural engineering.

Fatigue Design of Components

Author: G. Marquis
Publisher: Elsevier
ISBN: 9780080531601
Format: PDF, ePub, Docs
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This volume contains a selection of papers presented at Fatigue Design 95 held in Helsinki, Finland from 5-8 September 1995. The papers have been peer reviewed and present practical aspects for the design of components and structures to avoid fatigue failure. Topics covered include: fatigue design experiences, ground vehicle components, component reliability, multiaxial fatigue, notch analysis, service loading, welded structures, probabilistics aspects in fatigue, fatigue design optimization.

Multiaxial Notch Fatigue

Author: Luca Susmel
Publisher: Elsevier
ISBN: 1845695836
Format: PDF, ePub, Docs
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Metal and composite components used in structural engineering not only contain geometrical features resulting in stress concentration phenomena, but they are also subjected to in-service multiaxial fatigue loading. To address the problem, structural engineers need reliable methodologies which allow for an adequate margin of safety. The book summarises methods devised by the author to design real components against multiaxial fatigue by taking full advantage not only of nominal but also of local stress-strain quantities. The book begins by reviewing definitions suitable for calculating the stress-strain quantities commonly used to perform fatigue assessment. The Modified Wöhler Curve Method is then explained in detail, by focusing attention on both the high- and the medium-cycle fatigue regime. The existing links between the multiaxial fatigue criterion and physical properties are also discussed. A procedure suitable for employing the method developed by the author to estimate fatigue damage both in notched and in welded components is explained. The Modified Manson-Coffin Curve method is investigated in depth, by reviewing those concepts playing a fundamental role in the so-called strain based approach. Lastly, the problem of performing the fatigue assessment of composite materials is addressed by considering design parameters influencing composite behaviour under complex cyclic loading paths and those criteria suitable for designing real components against multiaxial fatigue. The book also contains two appendices summarising experimental data from the technical literature. These appendices provide a unique and highly valuable resource for engineers. The appendices summarise around 100 values of the material characteristic length L, experimentally determined by testing specimens made of different engineering materials and about 4500 experimental fatigue results generated by testing plain, notched and welded specimens under constant-amplitude proportional and non-proportional multiaxial fatigue loading are listed. Summarises methods devised by the author to design real components against multiaxial fatigue Reviews definitions suitable for calculating the stress-strain quantities commonly used to perform fatigue assessment Includes an in-depth explanation of both the Modified Wöhler Curve and Modified Manson-Coffin Curve Method

Fatigue Analysis of Welded Components

Author: E. Niemi
Publisher: Woodhead Publishing
ISBN: 1845696662
Format: PDF, Mobi
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This report provides background and guidance on the use of the structural hot spot stress approach to the fatigue design of welded components and structures. It complements the IIW recommendations for 'Fatigue Design of Welded Joints and Components' and extends the information provided in the IIW recommendations on 'Stress Determination for Fatigue Analysis of Welded Components'. This approach is applicable to cases of potential fatigue cracking from the weld toe. It has been in use for many years in the context of tubular joints. The present report concentrates on its extension to structures fabricated from plates and non-tubular sections. Following an explanation of the structural hot spot stress, its definition and its relevance to fatigue, the authors describe methods for its determination. Stress determination from both finite element analysis and strain gauge measurements is considered. Parametric formulae for calculating stress increases due to misalignment and structural discontinuities are also presented. Special attention is paid to the use of finite element stress analysis and guidance is given on the choice of element type and size for use with either solid or shell elements. Design S-N curves for use with the structural hot spot stress are presented for a range of weld details. Finally, practical application of the recommendations is illustrated in two case studies involving the fatigue assessment of welded structures using the structural hot spot stress approach. Provides practical guidance on the application of the structural hot-spot stress approach Discusses stress determination from both finite element analysis and strain gauge measurements Practical application of the recommendations is illustrated in two case studies