Determination of fatigue life for low probability of failure for different stress levels using 3-parameter Weibull distribution

This paper presents proposed characteristics of the S-N curve using the 2 and 3-parameter Weibull distribution for fatigue limit and limited life respectively. The parameters of the proposed model are estimated using the maximum likelihood method. Additionally, it has presented a method to estimate initial values for the likelihood function. Two applications are presented, whose S-N curves were characterized by using the results for rotary bending of 5355J2 + C and C45 + C steels. The proposed S-N curves can be used to determine the fatigue life for low probability of failure, e.g. 1%, which is not recommended by ASTM E-739-91, when using a normal distribution.