Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 02, 2019 - November 04, 2019
Effects of surface defect on bending fatigue limit of spring steel (JIS-SUP9A) was investigated. Bending fatigue tests were carried out under stress ratio of R=－2, －1, 0 and 0.4 for smooth specimens and specimens containing a semicircular surface slit with the depth of a=30, 60 and 400 μm These results showed that the maximum defect size which does not affect the fatigue limit shows the stress ratio dependency. Further, prediction of fatigue limit of smooth specimen Δσw0 and threshold stress intensity factor range ΔK(L)th at arbitrary stress ratio became possible. Predicted value agreed with experimental results. Fatigue limit of micro defects less than 100 μm and macro defects over 100 μm was successfully predicted using new fatigue limit prediction equation.
