In a cumulative damage evaluation, the result is a field named interface.fus. This is the fatigue usage factor, which describes the accumulated relative damage. Values of fus below 1 indicate that the stress history experienced does not lead to fatigue.

The S-N curve relates the applied stress to the permissible number of cycles to fatigue. For high loads, the stress that corresponds to 0.1 cycles is taken as the highest stress that can be experienced in the material. If the loading results in a stress which exceeds this limiting value, an error message displays stating that static failure is expected and no solution is provided. For low loads the Cycle cutoff parameter, Ncut, is used to obtain the lower stress limit, which can be seen as the endurance limit. If stresses are below this value they are considered not to be damaging and they do thus not contribute to fus.

Two additional variables describe the stress history in the point having the highest fatigue usage: interface.csc and interface.rus. The first variable defines the number of counted stress cycles in the load history within a certain stress amplitude and mean stress range. The second variable defines the relative usage factor, which is a ratio between fatigue usage of a stress cycle in a certain range and the fatigue usage factor.