J. Zapatero et al., ON THE USE OF THE STRIP-YIELD MODEL TO PREDICT FATIGUE-CRACK GROWTH UNDER IRREGULAR LOADING, Fatigue & fracture of engineering materials & structures, 20(5), 1997, pp. 759-770
In this paper, the behaviour of the LEFM strip-yield model proposed by
Newman and implemented in the FASTRAN II computer program is analyzed
. The capabilities of the model to predict crack growth life under var
iable amplitude loading is considered. Special attention is paid to th
e effect of the constraint factors used to consider the stress conditi
on (plane stress to plane strain), the effect of the finite length loa
ding sequence and the effect of overloads into an irregular loading hi
story. The results of simulation for 30 different loading histories ob
tained from the same stationary random process are analyzed and compar
ed with the experimental results obtained for 2024-T351 aluminium allo
y. The simulated lives present a fairly good fit with the experimental
results, with a strong influence of the constraint factor selected an
d of the maximum peak in the loading history. Although predictions are
usually good, it has been found that for any constraint factor produc
ing good life predictions (with respect to the mean value of the life
obtained with the 30 loading histories) the results of each particular
simulation may be over- or under-conservative depending on the maximu
m peak in the loading history used.