Fatigue life frequency dependence mechanisms

Perhaps the most important stress factor affecting corrosion fatigue is the frequency of the cyclic stress. Since corrosion is an essential component of the failure mechanism and since corrosion processes typically require time for the interaction between the metal and its environment, the corrosion-fatigue life of a metal depends on the frequency of the cyclic stress. Relatively low-stress frequencies permit adequate time for corrosion to occur high-stress frequencies may not allow sufficient time for the corrosion processes necessary for corrosion... 

Y. Miyano, M. Nakada, R. Muki (1997) Prediction of fatigue life of a conical shaped joint system for fiber reinforced plastics under arbitrary frequency, load ratio and temperatwe. Mechanics of Time-Dependent Mater. 1,143. 

The second method was called the dominant damage approach and assumes that fatigue and creep are independent mechanisms and that crack growth is determined by whichever is dominant. In this case, crack growth should be predominantly either cycle or time dependent. For example, if creep is the dominant damage mechanism, then plots of dn/df against a suitable TDFM should be independent of frequency and can be used to predict the fatigue life in terms of time under load rather than number of cycles. 

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