Course Information
Course Content
Historical overview; Fatigue design philosophies; Stress-life approach (SN diagram, mean stress effects, notches); Strain-life approach (hysteresis loop, Bauschinger effect, shakedown, ratcheting, energy methods, Neuber's rule); Damage-tolerance approach (introduction to fracture, crack tip plasticity, fracture toughness, crack growth stages, crack closure, small fatigue cracks); Physics of fatigue (imperfections in crystalline solids, slip bands, intrusions/extrusions, crack initiation, microstructure effects); Residual stresses (origin, measurement methods, relationship with fatigue); Fatigue under variable amplitude loading (load spectrums, linear and nonlinear cumulative damage models, load interaction and sequence effects, rainflow method, life estimation); Multiaxial fatigue (multiaxial stress state, proportional and nonproportional loading, yielding and plasticity in multiaxial fatigue, stress-based criteria (Sines method), strain- and energy-based approaches, critical plane approach (Fatemi-Socie model)); Environmental effects (corrosion, fretting, thermomechanical damage (creep and creep-fatigue interactions), neutron irradiation); Statistical aspects of fatigue (regression analysis of fatigue data, fatigue scatter, lognormal and Weibull distributions, tolerance limits, reliability analysis).
Textbook
Stephens, R. I., Fatemi, A., Stephens, R. R., & Fuchs, H. O. Metal Fatigue in Engineering. 2nd Edition, John Wiley & Sons, 2000.
Additional References
- Suresh, S. Fatigue of Materials. 2nd Edition, Cambridge University Press, 1998.
- Socie, D., & Marquis, G. Multiaxial Fatigue. 1st Edition, SAE International, 1999.
- Grandt Jr, A. F. Fundamentals of Structural Integrity. 1st Edition, John Wiley & Sons, 2003.
- Dowling, N. E. Mechanical Behavior of Materials. 5th Edition, Pearson Higher Ed, 2021.
- Cai, W., & Nix, W. D. Imperfections in Crystalline Solids. 1st Edition, Cambridge University Press, 2016.
Online Resources
- Prof. Darrell F. Socie's lecture videos on multi-axial fatigue (YouTube).
Grading
| Component | Weight |
|---|---|
| Quiz (3–4 quizzes) | 30% |
| Minor Exam | 30% |
| Major Exam | 40% |
Audit students must write the minor and major exams and maintain attendance ≥ 75%. The passing grade for audit is 40%.
Quizzes, Minor, and Major
3–4 quizzes will be conducted; exact date, time, and place will be notified later. Minor and major exams will be scheduled based on the institute timetable.
Homework
Homework will be assigned from time to time. These will not be graded; submission is not necessary. However, students are strongly encouraged to attempt the problems independently as they prepare for the quizzes, minor, and major exams.
Attendance
- Students are strongly encouraged to attend all lectures. Attendance will be recorded for each lecture. There are no marks for attendance.
- In case of absence due to unforeseen circumstances, notify the instructor via email within one week.
- Medical certificate from IIT Delhi hospital required for exam deferral or re-exam.