Abstract: : The necessity of getting P-Sa-Sm-N curved surface in the fatigue reliability analysis and design is discussed, and the principles for choosing the P-Sa-Sm-N curved surface are given. Two different approaches (moment method and maximum likelihood method) for fatigue tests are presented, and the methods are respectively suggested by which the P=Sa-Sm-N curved surface could be obtained from the data of the above two kinds of fatigue tests.

Key words: fatigue, reliability, moment method, maximum likelihood method