This paper deals with the numerical simulation of combined cycle fatigue (CCF), which is characterized by two periodic loads, whose frequencies are very different one from the other. Rather than using classical fatigue life estimations, a time transient evolution model is solved using a periodic time homogenization method. This latter is based on the assumption that the time scales associated with the two periodic loads are decoupled. Different results on academic as well as industrial examples are presented. An extension of the proposed method up to three time scales is eventually proposed in order to speed up the numerical simulations.