Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5014959 | International Journal of Fatigue | 2017 | 23 Pages |
Abstract
The aim of this experimental work is to determine the effect of turbine start/stop sequences (periodic underloads) on the fatigue threshold of small cycles at high stress ratio (baseline cycles) in two steels used in turbine runners, i.e. AISI 415 and 304L steels. Keeping Kmax constant, a first load procedure is conducted with decreasing ÎK to measure fatigue thresholds at 2Â ÃÂ 10â7Â mm/cycle under both constant amplitude loading and periodic underloads at various frequencies. Then a second load procedure is conducted to measure fatigue thresholds at 6.7Â ÃÂ 10â9 and 2Â ÃÂ 10â7Â mm/cycle under periodic underloads at one frequency with increasing ÎK of baseline cycles from zero. The periodic underloads applied above a certain frequency decrease the fatigue threshold measured at crack growth rate of 2Â ÃÂ 10â7Â mm/cycle. The decrease in fatigue threshold due to periodic underloads is about five times higher when it is measured at 6.7Â ÃÂ 10â9Â mm/cycle.
Related Topics
Physical Sciences and Engineering
Engineering
Mechanical Engineering
Authors
M. Hassanipour, Y. Verreman, J. Lanteigne,