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a b s t r a c tThe plane-strain crack subjected to mode I cyclic loading under small scale yielding was analysed. The influence of the load range, load ratio and overload on the near-tip deformation-, stress-and strain-fields was studied. Although the near-tip zones of appreciable cyclic plastic flow for all loading regimes matched closely one another, when scaled with (DK/r Y ) 2 , the activities of plastic flow within them manifested dependence on K max and K min , as well as on overload. Cyclic trajectories of the crack-tip opening displacement (CTOD) converged to stable self-similar loops of the sizes proportional to DK 2 and positions in CTOD-K plane dependent on the maximum K along the whole loading route, including an overload. Computed near-tip deformation evidenced plastic crack advance, this way visualising of the Laird-Smith concept of fatigue cracking. This crack growth by blunting-resharpening accelerated with rising DK and was halted by an overload. Crack closure upon unloading had no place. The affinities were revealed between computed near-tip stress-strain variables and the experimental trends of the fatigue crack growth rate, such as its dependence on K max and K min (or DK and K max ), and retardation by overload. Thus, the effects of loading parameters on fatigue cracking, hitherto associated with crack closure, are attributable to the stress-strain fields in front of it as the direct drives of the key fatigue constituents -damage accumulation and bond breaking.

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