Practical Residual Stress Measurement Methods E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 556

Veröffentlichungsjahr: 2013

Beschreibung

An introductory and intermediate level handbook written in pragmatic style to explain residual stresses and to provide straightforward guidance about practical measurement methods.

Residual stresses play major roles in engineering structures, with highly beneficial effects when designed well, and catastrophic effects when ignored.  With ever-increasing concern for product performance and reliability, there is an urgent need for a renewed assessment of traditional and modern measurement techniques.  Success critically depends on being able to make the most practical and effective choice of measurement method for a given application.

Practical Residual Stress Measurement Methods provides the reader with the information needed to understand key residual stress concepts and to make informed technical decisions about optimal choice of measurement technique.  Each chapter, written by invited specialists, follows a focused and pragmatic format, with subsections describing the measurement principle, residual stress evaluation, practical measurement procedures, example applications, references and further reading.  The chapter authors represent both international academia and industry.  Each of them brings to their writing substantial hands-on experience and expertise in their chosen field.

Fully illustrated throughout, the book provides a much-needed practical approach to residual stress measurements.  The material presented is essential reading for industrial practitioners, academic researchers and interested students.

Key features:
• Presents an overview of the principal residual stress measurement methods, both destructive and non-destructive, with coverage of new techniques and modern enhancements of established techniques
• Includes stand-alone chapters, each with its own figures, tables and list of references, and written by an invited team of international specialists

Leseprobe

Table of Contents

Title Page

Copyright

Dedication

List of Contributors

Preface

Chapter 1: Overview of Residual Stresses and Their Measurement

1.1 Introduction

1.2 Relaxation Measurement Methods

1.3 Diffraction Methods

1.4 Other Methods

1.5 Performance and Limitations of Methods

1.6 Strategies for Measurement Method Choice

References

Chapter 2: Hole Drilling and Ring Coring

2.1 Introduction

2.2 Data Acquisition Methods

2.3 Specimen Preparation

2.4 Hole Drilling Procedure

2.5 Computation of Uniform Stresses

2.6 Computation of Profile Stresses

2.7 Example Applications

2.8 Performance and Limitations of Methods

References

Chapter 3: Deep Hole Drilling

3.1 Introduction and Background

3.2 Basic Principles

3.3 Experimental Technique

3.4 Validation of DHD Methods

3.5 Case Studies

3.6 Summary and Future Developments

Acknowledgments

References

Chapter 4: The Slitting Method

4.1 Measurement Principle

4.2 Residual Stress Profile Calculation

4.3 Stress Intensity Factor Determination

4.4 Practical Measurement Procedures

4.5 Example Applications

4.6 Performance and Limitations of Method

4.7 Summary

References

Chapter 5: The Contour Method

5.1 Introduction

5.2 Measurement Principle

5.3 Practical Measurement Procedures

5.4 Residual Stress Evaluation

5.5 Example Applications

5.6 Performance and Limitations of Methods

5.7 Further Reading On Advanced Contour Method Topics

Acknowledgments

References

Chapter 6: Applied and Residual Stress Determination Using X-ray Diffraction

6.1 Introduction

6.2 Measurement of Lattice Strain

6.3 Analysis of Regular dφψ vs. sin2ψ Data

6.4 Calculation of Stresses

6.5 Effect of Sample Microstructure

6.6 X-ray Elastic Constants (XEC)

6.7 Examples

6.8 Experimental Considerations

6.9 Summary

Acknowledgments

References

Chapter 7: Synchrotron X-ray Diffraction

7.1 Basic Concepts and Considerations

7.2 Practical Measurement Procedures and Considerations

7.3 Angle-dispersive Diffraction

7.4 Energy-dispersive Diffraction

7.5 New Directions

7.6 Concluding Remarks

References

Chapter 8: Neutron Diffraction

8.1 Introduction

8.2 Formulation

8.3 Neutron Diffraction

8.4 Neutron Diffractometers

8.5 Setting up an Experiment

8.6 Analysis of Data

8.7 Systematic Errors in Strain Measurements

8.8 Test Cases

Acknowledgments

References

Chapter 9: Magnetic Methods

9.1 Principles

9.2 Magnetic Barkhausen Noise (MBN) and Acoustic Barkhausen Emission (ABE)

9.3 The MAPS Technique

9.4 Access and Geometry

9.5 Surface Condition and Coatings

9.6 Issues of Accuracy and Reliability

9.7 Examples of Measurement Accuracy

9.8 Example Measurement Approaches for MAPS

9.9 Example Applications with ABE and MAPS

9.10 Summary and Conclusions

References

Chapter 10: Ultrasonics

10.1 Principles of Ultrasonic Stress Measurement

10.2 History

10.3 Sources of Uncertainty in Travel-time Measurements

10.4 Instrumentation

10.5 Methods for Collecting Travel-time

10.6 System Uncertainties in Stress Measurement

10.7 Typical Applications

10.8 Challenges and Opportunities for Future Application

References

Chapter 11: Optical Methods

11.1 Holographic and Electronic Speckle Interferometric Methods

11.2 Moiré Interferometry

11.3 Digital Image Correlation

11.4 Other Interferometric Approaches

11.5 Photoelasticity

11.6 Examples and Applications

11.7 Performance and Limitations

References

Further Reading

Index

This edition first published 2013

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Library of Congress Cataloging-in-Publication Data

Practical residual stress measurement methods / edited by Gary S. Schajer.

pages cm

Includes bibliographical references and index.

ISBN 978-1-118-34237-4 (hardback)

1. Residual stresses. I. Schajer, Gary S., editor of compilation.

TA648.3.P73 2013

620.1′123–dc23

2013017380

A catalogue record for this book is available from the British Library.

ISBN 9781118342374

Cover design and graphics preparation: Yitai Liu

This book is dedicated to the memory of

Iain Finnie

late Professor of Mechanical Engineering at the University of California, Berkeley, a pioneer developer of the Slitting Method for measuring residual stresses.

Respectfully dedicated in appreciation of his encouragement, teaching, mentorship and personal friendship.

List of Contributors

Don E. Bray, Don E. Bray, Inc., Texas, USA

David J. Buttle, MAPS Technology Ltd., GE Oil & Gas, Oxford, UK

Adrian T. DeWald, Hill Engineering, LLC, California, USA

Michael R. Hill, Department of Mechanical and Aerospace Engineering, University of California, Davis, California, USA

Thomas M. Holden, National Research Council of Canada, Ontario, Canada (Retired)

Conal E. Murray, IBM T.J. Watson Research Center, New York, USA

Drew V. Nelson, Stanford University, Stanford, California, USA

I. Cevdet Noyan, Columbia University, New York, USA

Michael B. Prime, Los Alamos National Laboratory, New Mexico, USA

Clayton O. Ruud, Pennsylvania State University, Washington, USA (Retired)

Gary S. Schajer, University of British Columbia, Vancouver, Canada

David J. Smith, University of Bristol, Bristol, UK

Philip S. Whitehead, Stresscraft Ltd., Shepshed, Leicestershire, UK

Philip J. Withers, University of Manchester, Manchester, UK

Preface

Residual stresses are created by almost every manufacturing process, notably by casting, welding and forming. But despite their widespread occurrence, the fact that residual stresses occur without any external loads makes them easy to overlook and ignore. This neglect can cause great design peril because residual stresses can have profound influences on material strength, dimensional stability and fatigue life. Sometimes alone and sometimes in combination with other factors, unaccounted for residual stresses have caused the failure of major bridges, aircraft, ships and numerous smaller structures and devices, often with substantial loss of life. At other times, residual stresses are deliberately introduced to provide beneficial effects, such as in pre-stressed concrete, shot-peening and cold hole-expansion.

Starting from early curiosities such as “Rupert's Drops,” understanding of the character and mechanics of residual stresses grew with the rise in the use of cast metals during the Industrial Revolution. The famous crack in the Liberty Bell is due to the action of residual stresses created during casting. Early methods for identifying the presence of residual stresses involved cutting the material and observing the dimension changes. With the passage of time, these methods became more sophisticated and quantitative. Complementary non-destructive methods using X-rays, magnetism and ultrasonics were simultaneously developed.

Modern residual stress measurement practice is largely based on the early historical roots. However, the modern techniques bear the same relationship to their predecessors as modern jet planes to early biplanes: they share similar conceptual bases, but in operational terms the current measurement techniques are effectively “new.” They have attained a very high degree of sophistication due to greatly increased conceptual understanding, practical experience and much more advanced measurement/computation capabilities. All these factors join to give substantial new life into established ideas and indeed to produce “new lamps for old.”

Conceptual and technological progress has been a collective endeavor by a large group of people. The list of names is a long and distinguished one. To paraphrase Isaac Newton's words, the present Residual Stress community indeed “stands on the shoulders of giants.” A particular one of these giants that several of the contributors to this book were privileged to know and learn from, was Iain Finnie, late Professor of Mechanical Engineering at the University of California, Berkeley. Professor Finnie was a pioneer of the Slitting Method, described in detail in Chapter 4 of this book. I join with the other authors in dedicating this book to him as a sign of respect and of appreciation for his encouragement, teaching, mentorship and personal friendship. Those of us who aspire to be researchers and teachers can do no better than look to him for example.

On a personal note, I would like to express my sincere gratitude and appreciation to all the chapter authors of this book. The depth of their knowledge and experience of their various specialties and their generous willingness to share their expertise makes them a true “dream team.” They have been extraordinarily patient with all my editorial requests, both large and small, and have worked with me with grace and patience. Thank you, you have been good friends!

I also would like to thank the staff at John Wiley & Sons for the support and encouragement of this project, and for the careful way they have carried forward every step in the production process.

And finally, more personally, I would like to acknowledge my late parents, Leonard and Lilly Schajer, whose fingerprints are to be found on these pages. They followed the biblical proverb “Train up a child in the way he should go: and when he is old, he will not depart from it.” In keeping with their philosophy, the royalties from the sale of this book have been directed to support students in financial need through the Leonard and Lilly Schajer Memorial Bursary at the University of British Columbia. All book contributors have graciously supported this endeavor and in this way hope to add to the available shoulder-space on which the next generation may stand.

Gary SchajerVancouver, CanadaApril 2013

Chapter 1

Overview of Residual Stresses and Their Measurement

Gary S. Schajer1 and Clayton O. Ruud2

1University of British Columbia, Vancouver, Canada

2Pennsylvania State University, Washington, USA (Retired)

1.1 Introduction

1.1.1 Character and Origin of Residual Stresses

Residual stresses are “locked-in” stresses that exist in materials and structures, independent of the presence of any external loads [1]. The stresses are self-equilibrating, that is, local areas of tensile and compressive stresses sum to create zero force and moment resultants within the whole volume of the material or structure. For example, Figure 1.1 schematically illustrates how a residual stress distribution through the thickness of a sheet of toughened glass can exist without an external load. The tensile stresses in the central region balance the compressive stresses at the surfaces.

Figure 1.1 Schematic diagram of the cross-section of a sheet of toughened glass showing how residual stresses can exist in the absence of an external load

Almost all manufacturing processes create residual stresses. Further, stresses can also develop during the service life of the manufactured component. These stresses develop as an elastic response to incompatible local strains within the component, for example, due to non-uniform plastic deformations. The surrounding material must then deform elastically to preserve dimensional continuity, thereby creating residual stresses. The mechanisms for creating residual stresses include:

1. Non-uniform plastic deformation. Examples occur in manufacturing processes that change the shape of a material including forging, rolling, bending, drawing and extrusion, and in service during surface deformation, as in ball bearings and railway rails.

2. Surface modification. Examples occur in manufacture during machining, grinding, plating, peening, and carburizing, and in service by corrosion or oxidation.

3. Material phase and/or density changes, often in the presence of large thermal gradients. Examples occur in manufacture during welding, casting, quenching, phase transformation in metals and ceramics, precipitation hardening in alloys and polymerization in plastics, as well as in service from radiation damage in nuclear reactor components and moisture changes in wood.

Residual stresses are sometimes categorized by the length scale over which they equilibrate [2]. Type I are macro residual stresses that extend over distances from mm upwards. These are the “macro stresses” that appear in manufactured components. Type II are micro residual stresses that extend over distances in the micron range, for example, between grains in metals. Type I macro-stress, whether residual or applied, is one cause of Type II micro-stresses. Finally, Type III are residual stresses that occur at the atomic scale around dislocations and crystal interfaces. The Type I macro stresses are the target of most of the measurement techniques described in this book. Several of the techniques can be scaled down and used also to measure Type II and possibly Type III stresses. However, for some of the diffraction methods, the presence of Type II stresses can impair attempts to measure Type I stresses.

Figure 1.2 schematically illustrates examples of some typical ways in which residual stresses are created in engineering materials. The diagrams illustrate how localized dimension changes require the surrounding material to deform elastically to preserve dimensional continuity, thereby creating residual stresses. For example, the upper left panel illustrates shot peening, where the surface layer of a material is compressed vertically by impacting it with small hard balls [8]. In response, the plastically deformed layer seeks to expand horizontally, but is constrained by the material layers below. That constraint creates compressive surface stresses balanced by tensile interior stresses, as schematically shown in the graph. A similar mechanism occurs with plastic deformation created in cold hole expansion and bending, although with completely different geometry. Phase transformations, such as martensitic transformations in steel, can also cause the dimensions of a part of material to change relative to the surrounding areas, also resulting in residual stresses.

Figure 1.2 Examples of some typical ways in which residual stresses are created in engineering materials. Reproduced with permission from [2], Copyright 2001 Maney