W. Zhang et Kj. Miller, A STUDY OF CUMULATIVE FATIGUE DAMAGE UNDER VARIABLE LOADING-MODE CONDITIONS, Fatigue & fracture of engineering materials & structures, 19(2-3), 1996, pp. 229-239
The accumulation of fatigue damage was investigated by studying deform
ation processes and the kinetics of short crack initiation and propaga
tion under variable loading-mode conditions. Fatigue tests were carrie
d out under push-pull and torsion, both separately and sequentially, t
hat is specimens were subjected to push-pull loading prior to torsion.
The results show that specimens tested in push-pull followed by torsi
on have a much longer fatigue life than virgin specimens. The mechanis
ms of this phenomenon were explored by experimental observations and t
heoretical analyses of crack initiation and propagation. The effect of
stress state on cumulative damage is described in some detail.