Abstract
Studies on fatigue strength under varying stress conditions are very important in the fields of fatigue research and machine design. So, in the past many researchers have conducted a great deal of fatigue tests under varying stress. The majority of these studies under varying stress have been done from the viewpoint of fatigue crack initiation and failure, and there were only few studies on the fatigue slip band initiation.
In this paper the effect of cumulative cycle ratio on fatigue slip band initiation was discussed. Fatigue tests were done on the specimens made from S10C and S35C (JIS standard). The experimental results are summarized as follows:
(1) Σ(n/N)≥1 for low-high stress sequence.
(2) Σ(n/N)≤1 for high-low and two level multiple repeated stress sequences.
