Page 503 - Biaxial Multiaxial Fatigue and Fracture

Geometry Variation and Lije Estimates of Biaxial Fatigue Specimens 487

used to modify the fatigue strength reduction factor, Kf. An attempt was made [ 113 to use a
similar approach for high strain situations by calculating a ‘critical volume’ and using a strain
energy based argument to modify the elastic strength reduction factor, Kf. However, this was
not supported by physical explanation. Moreover, it was argued previously [20] that total strain
energy density could not be used in the case of combined loading.
Further work was carried out [12] predominantly in the elastic field, using a similar local
damage zone approach to modify the Dang-Van parameter [13]. This was, to some extent, the
application of the Shatil and Smith gradient approach [6] to re-examine earlier work carried out
by papadopolos et al [9].

Table 1. Summary of subsurface fatigue models

Subsurface model Criterion Used Fatigue Regime

Flavenot and Skalli [SI HCF

Munday and Mitchell HCF
r71

Shatil and Smith [6] LCF and HCF

Papadopoulos and
Panoskaltsis [9, IO] Endurance

Qilafku et al. [SI . Xef HCF

Bentachfine et al. [ 111 LCF and HCF
kf

Qilafku et al. [ 121
HCF