Modern Metal Fatigue Analysis (PDF)

1 INTRODUCTION TO FATIGUE
1.1 Introduction—1.2 Description of the applied loading
—1.3 Endurance curves—1.4 Generalising fatigue data—1.5 Other factors which influence fatigue strength—1.6 Chapter contents—1.7 References

2 UNIAXIAL STRAIN-LIFE FATIGUE ANALYSIS
2.1 Introduction—2.2 True stress and strain—2.3 Fatigue life relationships—2.4 Cyclic stress-strain relationships—2.5 Material response to a sequence of strains—2.6 Effect of mean stress—2.7 Analysing local strain histories—2.8 The Smith-Watson-Topper relationship—2.9 Application of stress concentrations—2.10 Analysing nominal strain histories—2.11 Local strain analysis from a cycle histogram—2.12 Analysis of cast iron—2.13 Applicability of local strain analysis—2.14 Summary of strain-life equations—2.15 References

3 LOCAL STRAIN MATERIALS DATA
3.1 Introduction—3.2 The cyclic stress- strain curve—3.3 The strain-life curve—3.4 Practical testing—3.5 Approximating materials data—3.6 Applicability of materials data—3.7 References

4 SIGNAL PROCESSING FOR FATIGUE ANALYSIS
4.1 Introduction—4.2 Rainflow cycle counting—4.3 Level crossing analysis—4.4 Peak and valley counting—4.5 Range counting—4.6 Summary—4.7 References

5 FATIGUE ANALYSIS USING STRESS-LIFE (S-N) CURVES
5.1 Introduction—5.2 Application of stress concentrations—5.3 Complex load histories—5.4 Calculation of fatigue stress reserve factors—5.5 Analysis Of Variable Amplitude Stress Histories—5.6 Estimating materials fatigue data—5.7 Applicability of S-N curves—5.8 References

6 STRESS CONCENTRATIONS
6.1 Introduction—6.2 Fatigue strength reduction factor—6.3 Summary—6.4 References

7 BIAXIAL FATIGUE
7.1 Introduction—7.2 Stress and strain relationships—7.3 Static yield criteria—7.4 Multiaxial fatigue using equivalent stress or strain—7.5 Critical plane analysis—7.6 Wang-Brown criterion—7.7 Effects of mean stress—7.8 Dang Van criterion—7.9 Summary of fatigue-life relationships—7.10 References

8 FATIGUE ANALYSIS FROM FINITE ELEMENT MODELS
8.1 Introduction—8.2 Terminology of finite element analysis—8.3 Analysing a linear elastic model with single applied load history—8.4 Analysing a linear elastic model with multiple applied loads—8.5 Analysing a sequence of data sets—8.6 Frequency-domain finite element analysis—8.7 Other types of loading—8.8 Output—8.9 Speed considerations—8.10 Accuracy of results—8.11 Elastic-plastic FEA—8.12 Recent developments—8.13 Summary—8.14 References

9 USING STATISTICS IN FATIGUE
9.1 Introduction—9.2 Gaussian distribution—9.3 The Weibull distribution—9.4 Failure probability in design—9.5 References

10 CRACK PROPAGATION
10.1 Introduction—10.2 The purpose of fracture mechanics—10.3 Stresses at the crack tip—10.4 Fracture toughness—10.5 Plasticity—10.6 Multiaxial stresses at the crack tip—10.7 Stress corrosion cracking—10.8 Crack propagation—10.9 Crack propagation calculations for complex components.—10.10 Reference

11 FATIGUE OF WELDED STEEL JOINTS
—11.1 Introduction—11.2 Weld classification—11.3 Fatigue life curves—11.4 Calculation of applied stress—11.5 Effect of mean stress—11.6 Effect of material UTS—11.7 Calculation of probability of failure—11.8 Practical fatigue calculations—11.9 Hot-spot approach to fatigue of welds—11.10 Structural stress approach to fatigue of welds—11.11 References and further reading

12 FATIGUE ANALYSIS FROM THE PSD
12.1 Introduction—12.2 Why fatigue analysis from PSD’s?—12.3 Early methods of fatigue analysis from the PSD—12.4 Calculation of rainflow ranges from a PSD—12.5 Summary—12.6 References

13 FATIGUE TEST SIGNALS AND CUMULATIVE DAMAGE
13.1 Introduction—13.2 Constant amplitude tests—13.3 Block loading test programs—13.4 Editing signals to remove small cycles—13.5 Effect of larger cycles—13.6 Generic test signals—13.7 Summary—13.8 References

14 PRACTICAL FATIGUE ANALYSIS
14.1 Introduction—14.2 Locating strain gauges—14.3 Data recording—14.4 Short term recording or long term analysis—14.5 Sampling signals—14.6 Length of measured data—14.7 Peak-valley extraction with cycle omission—14.8 Interpreting analysis results—14.9 References

The contents have been developed as course notes for training courses presented to engineers who need to apply fatigue knowledge in engineering design, fatigue testing and failure investigation. Course delegates regularly report that much of the course material is new information. The book will also be of value to undergraduates on mechanical engineering courses.

REVIEW

Professor Andrew Sherry Director, Materials Performance Centre, and Director, Nuclear EngD Centre University of Manchester

John Draper’s book Modern Metal Fatigue Analysis provides a highly readable and comprehensive introduction to the study of fatigue behaviour of metals and alloys for students, a description of the details of fatigue assessment methods for the design engineer, and includes a level of detail that expert practitioners will find useful. The book opens with a general description of the key elements of fatigue crack initiation and propagation under cyclic loading. With clear figures, a clarity of description, and many practical examples, the book outlines the material response to simple and complex cyclic loading.

Modern Metal Fatigue Analysis opens with an overview of hysteresis, stress concentration and crack closure. Fatigue test methods are described and engineering approaches for the assessment of fatigue are presented. This includes a summary of data requirements, a description of the rainfall method, and an overview of stress concentration factors for notches. The tools available to the design and structural integrity engineer for considering fatigue under uniaxial, biaxial and triaxial stress states are described, including simple engineering approaches on the one hand and more complex finite element analysis on the other. A description of the treatment fatigue crack growth is also provided with characteristic clarity. This incorporates an overview of the principles of linear elastic fracture mechanics including an overview of the meaning and application of the stress intensity factor.

Finally Modern Metal Fatigue Analysis addresses issues relating to the statistical analysis of fatigue behaviour, issues associated with the analysis of welds (including residual stresses), the use of the power spectral density diagram (auto-spectral density), and the concept of cumulative damage. The book includes an appendix describing the Verity® mesh-insensitive structural stress method for fatigue analysis of welded joints.

John Draper has succeeded in providing a comprehensive, readable and clear scientific textbook on fatigue and fatigue assessment that materials science and engineering students, design engineers and structural integrity practitioners will find extremely useful. Professor Andrew Sherry Director, Materials Performance Centre, and Director, Nuclear EngD Centre University of Manchester.