It develops under different conditions of loading with or without:

• triaxiality effects,
• notch effects,
• plastic components,
• residual stresses,
• corrosion,
• thermal gradients,
• welded areas...

Polycyclic or Low-Cycle Theories are applied to quantify the Fatigue Performance of Strucutres in Service:

• Goodmann-Smith,
• Locati,
• Dang Van,
• Manson-Coffin...