Fig. 5 Examples of the assessment of the present simulation for the
cracked area plotted against number of loading cycles for two-step
loading tests with low-to-high, O-A-B-C, and high-to-low, O-B-A-D,
sequences compared with the corresponding behavior due to the
application of CSA virtual tests having the two involved stress
amplitudes 390 MPa, O-A-D\, and 432.5
MPa, O-B-C\; (a) and (b) present the
behavior of two specimens with different surface configurations.
Figure 6 presents the results of \(A_{C}\) against \(\frac{N}{N_{f}}\)for four virtual CSA tests. The figure shows that for a given ratio
of\(\text{\ \ }\frac{N_{1}}{{N_{f}}_{1}\ }\ \)in TSL tests with L-H
sequence, the ratio \(\frac{N_{2}}{{N_{f}}_{2}\ }\) increases as the
difference between the two involved stresses increases. With the H-L
sequence, \(\frac{N_{2}}{{N_{f}}_{2}\ }\)decreases with an increase in
that difference.