Fig. 11 Prediction of the present simulation against the corresponding experimental fatigue lifetime 3 for six repeated two-step loading block tests, T1-T6, with the parameters listed in Table 1(b); Each virtual test was carried out seven times with different specimen configurations.
The stresses listed in Table 1 are higher than the material fatigue limit. The cracks analyzed in the present work are short and subjected to relatively high stresses. Most of those cracks grow in surface grains experiencing plastic deformation in the course of the tensile and compressive parts of the loading cycles. Thus, the well-known effect of the high load on the retardation behavior of the tips advancing in those grains as a result of changing the load to the low level is ignored58, 59 in the present work. The results presented in Fig. 11 indicate that the lower load of a loading block is applied for a number of cycles less than that required for the full development of such an effect.