Effect of frequency and temperature on fatigue of metals

Some of the properties of ductile metals which are exhibited under fatigue loading may be described in a qualitative manner on the basis of a physical model that is familiarly called the standard linear solid. Its importance lies in the fact that it shows a relation that must exist between temperature and frequency. On the basis of this model it seems possible to conclude from phenomenological considerations that the critical temperatures observed by Daniels and Darn and by Valluri are not real critical values but are simply temperatures associated with corresponding frequencies of fatigue stressing above which the fatigue behavior changes. It is suggested that the reason why one does not observe the effect of frequency at room temperature in normal engineering practice is that the critical frequency associated with room temperature differs substantially from those frequencies customarily used in fatigue testing.