Font Size: 

The paper presents results of numerical modelling of elastic-plastic stressand strain fields at the tip of a propagating crack under cyclic loading. A particularmotivation is to investigate the difference in fatigue crack growth rates previouslyobserved in tests on M(T) and C(T) specimens made of 25CrMo4 (EA4T) steel. Thestress field triaxiality (constraint) is considered as a factor influencing the deformationand, accordingly, closure behaviour at the crack tip. Among numerical issues studied inthe paper are the strain hardening behaviour, consideration of the crack face contact,definition of the onset of crack opening, possible simplifications of numerical modellingby using the boundary layer formulation. The numerical results suggest that, using theeffective stress intensity factor range, a reasonable explanation to the experimentalfindings can be provided.