Fig.
8 Examples of the assessment of the present simulation for the number of
existing cracks plotted against cracked area due to the application of
CAL having different stress amplitudes utilizing specimens with
different surface configurations.
In Fig. 8, Z is plotted against \(A_{C}\) for different applied
stresses. With a decrease in the applied stress and for the
same\(\text{\ A}_{C}\), there is an increase in Z and, hence, an
increase in the number of advancing tips. The implication, here, is that
for the same \(A_{C}\) the average length of the existing surface
cracks,\(\text{\ l}_{\text{av}},\) decreases as the applied stress
decreases. Figure 9 exhibits the variation of \(\text{\ l}_{\text{av}}\)with the cycle ratio for different applied stresses as given by the
present simulation. Both \(\text{\ l}_{\text{av}}\) and\(\text{\ A}_{C}\) behave similarly. Figure 9 supports the
experimentally observed \(\sum\frac{N}{N_{f}\ }\) in the case of
TSL tests with L-H and H-L sequences.