A methodology to determine a conditional probability density distribution surface from S–N data

A conditional probability density distribution surface (CPDDS) is constructed by two functions in this paper. One is the function of population mean and the stress level; the other is the function of standard deviation and the stress level. The surface represents the probability density curve of fatigue life changing with the stress level. A new definition of fatigue limit as well as the determination method is given in this paper according to the small probability event of CPDDS. The proposed method can save considerable cost and time in the determination of fatigue limit.