Effect of LCF on HCF crack growth of Ti-17

Elastic–plastic fatigue crack growth analysis under variable amplitude loading spectra

“…However, experiments show that under-loads do not create retardation effect as the overloads do and they can even cause a slight acceleration of the fatigue crack growth [57].…”

“…Russ [57] with the aim to investigate the load-interaction effect in the case of constant amplitude loading with repeatable single underloads. The fatigue crack growth was studied in compact tension specimens (Figure 6-2) made of Ti-17 titanium alloy subjected to special type of loading spectra shown in Figure 6-3.…”

“…The fatigue crack growth was studied in compact tension specimens (Figure 6-2) made of Ti-17 titanium alloy subjected to special type of loading spectra shown in Figure 6-3. The stress intensity factor expression used in the study [57] was: …”

“…All relevant data concerning analysed loading spectra were borrowed from reference [57] and they are also shown in Table 7-1. These include the maximum applied load, the ratio between maximum and minimum applied load of the baseline loading cycles and the underloading levels, and the number of spacing cycles between underloads.…”

“…Cyclic stress-strain experimental data was also borrowed from reference [57]. The plastic strain vs. stress amplitude data points were extracted from the experimental total strain vs. stress data according to the standard procedure given in reference [54].…”