For many metals, including steel and aluminum, no damage occurs once a constant amplitude load drops below the endurance limit (infinite life). This behavior can be represented by 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.