Understanding Fatigue
Fatigue cracks form when a component is subjected to repeated cycles of stress, even at levels well below the material's yield strength. Each cycle causes microscopic damage that accumulates until a crack initiates and grows.
Common Causes
Fatigue cracking is driven by:
- Repeated loading and unloading cycles
- Stress concentrations at welds, holes and changes in section
- Poor weld profile or defects
- Corrosion accelerating crack initiation
- Overloading and vibration
Detecting Fatigue Cracks
Because fatigue cracks start at the surface, eddy current and magnetic particle testing are ideal for detecting them early — before they grow to a critical size.