Extrapolation Method to Determine the Endurance Limit of Fatigue
Bai Zhaoyu(1),Meng Xianhong(1),Xu Aling(2)
(1 Division 508, Department of flight vehicle design and applied mechanics, Beijing University of Aeronautics and Astronautics, Beijing, 100083) (2 Chinese Aero Poly-technology Establishment, Beijing 100028)

Abstract: In this paper by using the method of grouping instead of up and down method, an extrapolation method for determining the endurance limit of fatigue is put forward. Firstly, with the endurance limit of fatigue as parameters the expression of S-N curves is presented. Then, the experimental data of four testing groups are substituted into the above expression results in four equations. Eliminating other parameters of material in the four equations, the transcendental equation for solving the endurance limit of fatigue is achieved. After the endurance limit of fatigue is obtained, the other parameters of material can be fitted by using the least square method according to the experimental results mentioned above. By means of this method, the whole median S-N curve can be carried out, and then testing period and expense can be reduced obviously.
Keywords: endurance limit of fatigue, method of grouping, up and down method, extrapolation method.