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The total period, Nf, to failure is considered, which includes the periods offatigue macrocrack initiation, Ni, and propagation, Np, i.e.: Nf = Ni + Np. Fatiguefracture of materials has been modelled as a process of initiation of a macrocrack oflength ai = d* (the magnitude of d* is a material constant), which is successively repeated(step-by-step) during its growth. As a result the "local stress range, *Äóy , versusmacrocrack initiation period, Ni " relationship, which was established for notchedspecimens, might be applied to the determination of the "macrocrack growth rate, da/dN ,versus effective stress intensity factor range, ÄKeff" relationship and vice versa.