There are 3 major fatigue-life methods, which aim to predict the number of cycles to failure under specific loading conditions.
- Stress-Life Method
- Considers stage I to III of crack nucleation and propagation
- Estimates the life of a complete fracture, ignoring details of crack initiation and propagation.
- Based on nominal stress levels only, applying stress concentration factors at notches, no accounting for local plastic strain.
- Based on empirical data as opposed to theory
- Least accurate
- Traditional, easy to implement for wide range of design applications
- Adequately assess high-cycle fatigue applications
- Strain-Life Method
- Linear-Elastic Fracture Mechanics Method