Fig. 6 Examples of the assessment of the present simulation for the
cracked area plotted against cycles ratio due to the application of CAL
having different stress amplitudes utilizing specimens with different
surface configurations.
The results of the two virtual tests shown in Fig. 6 for the CSA of
432.5 MPa and 390 MPa are further considered in the form
of\(\text{\ A}_{C}\) plotted against\(\ \frac{N}{N_{f}}\). For the
same\(\ \frac{N}{N_{f}}\), the higher the stress amplitude the higher\(A_{C}\) is. For the same\(\text{\ A}_{C}\), the lower the stress
amplitude the higher \(\frac{N}{N_{f}}\ \)is. The two points A and B in
Fig. 5 are duplicate in Fig. 6. Figure 6 concludes that based on the
results of the simulation of the CSA tests the\(\ \sum{\ \frac{N}{N_{f}\ }}\) in the TSL with L-H
sequence,\(\ {=S}_{1\ },\ \) should be greater than 1 and in the case
of H-L
sequence\(\ \sum{\ \frac{N}{N_{f}\ }}\),\(\ {=S}_{2\ },\ \)should be less than 1.
However, Fig. 5 shows that the \(\sum\frac{N}{N_{f}\ }\) given by
the simulation of the corresponding TSL test with the L-H sequence is
slightly less than\(\ S_{1}\). Further, the\(\sum\frac{N}{N_{f}\ }\) corresponding to the TSL test with the
H-L sequence is appreciably less than\(\text{\ S}_{2}\). In spite of
points A and B having equal \(A_{C}\), the cracking damage configuration
(CDC) of the specimen at point B due to the application of the CSA 432.5
MPa and that at point A due to the application of the CSA 390 MPa are
different as discussed below.