Abstract
In the previous report, it was found, from fatigue tests using notched round bar specimens, that critical distance approach is available for fatigue life prediction at stress concentration part at low cycle regime. In this study, in order to confirm the capability of the life assessment method for stress concentration part at contact edge such as dovetail structure in gas turbine disks, fatigue tests using the dovetail structured specimens with contact configuration of Ni-based single crystal superalloy were conducted at high temperature. Critical distance, which means the region of stress field related to the fatigue process zone, was obtained from fatigue tests and analyses using notched round bar specimens. The average stresses within the critical distance at the contact edge, where fatigue crack initiates, for dovetail structured specimens were obtained. It was found that the fatigue life of dovetail structured specimen can be predicted within the almost factor of 2 scatter bands by life assessment method using the average stresses.
