Infinite Life Fatigue

For many metals including steel and aluminum no damage occurs once the constant amplitude loading drops below the endurance limit (infinite life). This behavior can be illustrated using a straight line in a logarithmic diagram called S-N curve. The kink point usually occurs between one and ten million load cycles.

In many engineering applications the load cycle numbers are very high, thus the fatigue assessment is a rather simple check of the maximum service stress ranges against the endurance limit. All codes implemented in LIMIT offer this assessment type.