Fatigue is responsible for the majority of premature operational failures. It occurs when repeated loadings generate stresses, which although below the material's static allowable stresses, are above the level where microscopic damage is initiated, and if continued will result in cracking.

Fatigue analysis identifies the potential crack initiation sites and indicates how long a component can be expected to last within its allowable loading envelope.

The opportunities for savings are great - For high cycle fatigue a small reduction in stress can lead to a large increase in the life of a component.