Fatigue Limit in Metals

Is there a fatigue limit in metals? This question is the main focus
of this book.

Written by a leading researcher in the field, Claude Bathias
presents a thorough and authoritative examination of the coupling
between plasticity, crack initiation and heat dissipation for
lifetimes that exceed the billion cycle, leading us to question the
concept of the fatigue limit, both theoretically and
technologically.

This is a follow-up to the Fatigue of Materials and Structures
series of books previously published in 2011.

Contents

1. Introduction on Very High Cycle Fatigue.

2. Plasticity and Initiation in Gigacycle Fatigue.

3. Heating Dissipation in the Gigacycle Regime.

About the Authors

Claude Bathias is Emeritus Professor at the University of Paris
10-La Defense in France. He started his career as a research
engineer in the aerospace and military industry where he remained
for 20 years before becoming director of the CNRS laboratory ERA
914 at the University of Compiègne in France. He has launched
two international conferences about fatigue: International
Conference on the Fatigue of Composite Materials (ICFC) and Very
High Cycle Fatigue (VHCF).
This new, up-to-date text supplements the book Fatigue of
Materials and Structures, which had been previously published
by ISTE and John Wiley in 2011. A thorough review of coupling
between plasticity, crack priming, and thermal dissipation for
lifespans higher than a billion of cycle has led us to question the
concept of fatigue limit, from both the theoretical and
technological point of view. This book will address that and more.

Auteur
Claude Bathias is Emeritus Professor at the University of Paris 10-La Defense in France. He started his career as a research engineer in the aerospace and military industry where he remained for 20 years before becoming director of the CNRS laboratory ERA 914 at the University of Compiègne in France. He has launched two international conferences about fatigue: International Conference on the Fatigue of Composite Materials (ICFC) and Very High Cycle Fatigue (VHCF).

Résumé
Is there a fatigue limit in metals? This question is the main focus of this book.
Written by a leading researcher in the field, Claude Bathias presents a thorough and authoritative examination of the coupling between plasticity, crack initiation and heat dissipation for lifetimes that exceed the billion cycle, leading us to question the concept of the fatigue limit, both theoretically and technologically.
This is a follow-up to the Fatigue of Materials and Structures series of books previously published in 2011.

Contents

1. Introduction on Very High Cycle Fatigue.
   
   2. Plasticity and Initiation in Gigacycle Fatigue.
   3. Heating Dissipation in the Gigacycle Regime.

About the Authors

Claude Bathias is Emeritus Professor at the University of Paris 10-La Defense in France. He started his career as a research engineer in the aerospace and military industry where he remained for 20 years before becoming director of the CNRS laboratory ERA 914 at the University of Compiègne in France. He has launched two international conferences about fatigue: International Conference on the Fatigue of Composite Materials (ICFC) and Very High Cycle Fatigue (VHCF). This new, up-to-date text supplements the book Fatigue of Materials and Structures, which had been previously published by ISTE and John Wiley in 2011. A thorough review of coupling between plasticity, crack priming, and thermal dissipation for lifespans higher than a billion of cycle has led us to question the concept of fatigue limit, from both the theoretical and technological point of view. This book will address that and more.

Contenu

ACKNOWLEDGEMENTS vii

CHAPTER 1. INTRODUCTION ON VERY HIGH CYCLE FATIGUE 1

1.1. Fatigue limit, endurance limit and fatigue strength 1

1.2. Absence of an asymptote on the SN curve 5

1.3. Initiation and propagation 6

1.4. Fatigue limit or fatigue strength 7

1.5. SN curves up to 109 cycles 8

1.6. Deterministic prediction of the gigacycle fatigue
strength 10

1.7. Gigacycle fatigue of alloys without flaws 12

1.8. Initiation mechanisms at 109 cycles 13

1.9. Conclusion 13

1.10. Bibliography 14

CHAPTER 2. PLASTICITY AND INITIATION IN GIGACYCLE
FATIGUE 17

2.1. Evolution of the initiation site from LCF to GCF 17

2.2. Fish-eye growth 20

2.2.1. Fracture surface analysis 20

2.2.2. Plasticity in the GCF regime 23

2.3. Stresses and crack tip intensity factors around spherical
and cylindrical voids and inclusions 29

2.3.1. Spherical cavities and inclusions 29

2.3.2. Spherical inclusion 31

2.3.3. Mismatched inclusion larger than the spherical cavity it
occupies 31

2.3.4. Cylindrical cavities and inclusions 33

2.3.5. Cracking from a hemispherical surface void 35

2.3.6. Crack tip stress intensity factors for cylindrical
inclusions with misfit in both size and material properties 38

2.4. Estimation of the fish-eye formation from the
Paris-Hertzberg law 42

2.4.1. "Short crack" number of cycles 47

2.4.2. "Long crack" number of cycles 48

2.4.3. "Below threshold" number of
cycles 48

2.5. Example of fish-eye formation in a bearing
steel 49

2.6. Fish-eye formation at the microscopic level 52

2.6.1. Dark area observations 53

2.6.2. "Penny-shaped area" observations 54

2.6.3. Fracture surface with large radial ridges 56

2.6.4. Identification of the models 59

2.6.5. Conclusion 62

2.7. Instability of microstructure in very high cycle fatigue
(VHCF) 62

2.8. Industrial practical case: damage tolerance at 109 cycles
69

2.8.1. Fatigue threshold in N18 70

2.8.2. Fatigue crack initiation of N18 alloy 71

2.8.3. Mechanisms of the GCF of N18 alloy 73

2.9. Bibliography 74

CHAPTER 3. HEATING DISSIPATION IN THE GIGACYCLE
REGIME 77

3.1. Temperature increase at 20 kHz 77

3.2. Detection of fish-eye formation 81

3.3. Experimental verification of Nf by thermal
dissipation 83

3.4. Relation between thermal energy and cyclic plastic energy
85

3.5. Effect of metallurgical instability at the yield point in
ultrasonic fatigue 89

3.6. Gigacycle fatigue of pure metals 91

3.6.1. Microplasticity in the ferrite 95

3.6.2. Effect of gigacycle fatigue loading on the yield stress
in Armco iron 97

3.6.3. Temperature measurement on Armco iron 98

3.6.4. Intrinsic thermal dissipation in Armco iron 102

3.6.5. Analysis of surface fatigue crack on iron 105

3.7. Conclusion 109

3.8. Bibliography 110

INDEX 113