In a random vibration evaluation, the results are fields named interface.dfus, interface.fus, and interface.life. These are, respectively, the fatigue usage factor per unit time, the fatigue usage factor, and the fatigue life. Values of fus below 1 indicate that the stresses experienced over the duration of the event do not lead to fatigue.

To evaluate the risk for fatigue, each stress level encountered during the random vibration event must be related to the permissible number of cycles to fatigue. In the case where the S–N curve fatigue model is used, a stress that corresponds to 0.1 cycles is taken as the highest stress that can be experienced in the material. If a stress during the random vibration event 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. If a part of the structure experiences stresses that are low enough that no damage results, this corresponds to infinite life. The Life cutoff parameter, Lcut, can be used to specify a finite approximation to infinite life. This way, results from computations of fatigue life can be more easily visualized.