ME 7774: Fatigue of Materials and Structures
Offered Every Spring

Credit Hours: 3-0-3
Prerequisites:  AE 7772 or CEE 7772 or CHE 7772 or ME 7772 or MSE 7772, graduate standing or consent of instructor. 
Catalog Description: Mechanical and microstructural aspects of nucleation and growth of cracks under cyclic loading conditions, notch effects, cumulative damage, multiaxial loading and fatigue crack propagation. Crosslisted with AE, CEE, CHE, and MSE 7774.
Textbooks: Julie A. Bannantine, Jess J. Comer, and James L. Handrock, Fundamentals of Metal Fatigue Analysis; First Edition, Pearson Education, 1997.
 Subra Suresh, Fatigue of Materials; 2nd Edition, Cambridge University Press, 1998.
Instructors: David McDowell (ME), Richard Neu (ME), William Johnson (MSE), George Kardomateas (AE) 
Goals: To provide a working knowledge of state­of­the­art methods and contemporary issues of fatigue life prediction and associated physical processes, with emphasis on metal fatigue. 

 

Topics: 
Course Overview; Physics of Fatigue Processes
Crack nucleation
Crack propagation
     metals, polymers, ceramics
Stress­Strain Response of Metals
Monotonic tensile tests
Temperature and rate dependence
Cyclic response
     hardening, softening
     cyclic stress-strain curve
Strain Life Relationships: LCF, HCF
Stress-life and Basquin's Law
Coffin-Manson Law
Cyclic property estimates
Combined strain-life curve
Influence of Mean Stress, Surface Finish, Hardness
Role of mean stresses on small crack nucleation/growth
Models for mean stress effects
Load sequence effects on mean stress
Effects of surface finish and hardness on fatigue
Fatigue at Notches
Theoretical stress concentration, size effects and Kf
Neuber's rule and notch root stress-strain analysis
Load sequence effects on notch root behavior
Variable Loading
Cycle counting techniques and history reconstruction
Damage summation - linear and nonlinear approaches
Component calibration curves
Applications to loading spectra
Scatter in Fatigue
Probability distributions for scatter of
     fatigue strength
     fatigue life
Size effects and weak link theory
Scatter in HCF versus LCF
LEFM Concepts and growth laws for physically long cracks
Stress intensity factor and DK 
Cyclic crack tip fields
Paris growth law
Threshold and fracture regimes
Crack closure and DKeff 
Load sequence effects and closure/plasticity models
Growth of small/short cracks
Characteristics of microstructurally small crack growth
Mechanics considerations
Kitagawa diagram and HCF thresholds
Small cracks growing from notches
Transition to long crack behavior
Multiaxial fatigue
Historical overview of multiaxial HCF and LCF crack initiation
Critical plane observations for small fatigue cracks
Gamma plane representation
Recent models for multiaxial fatigue
Time-dependent and high temperature fatigue
Intergranular versus transgranular formation/growth
Interaction with bulk damage
Damage rate and damage mechanics approaches
Thermomechanical fatigue

Evaluation:

Homework (1/3)
Midterm (1/3)
Final (1/3)
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Revised July 2004