Abstract: According to the traditional fatigue constant life curve, the concept and the universal expression of the generalized fatigue constant life curve were proposed. Then, on the basis of the optimization method of the correlation coefficient, the parameter estimation formulas were induced and the generalized fatigue constant life curve with the reliability level p was given. From p-S_a-S_m curve, the two-dimensional probability distribution of the fatigue limit was derived. After then, three set of tests of LY11CZ corresponding to the different average stress were carried out in terms of the two-dimensional up-down method. Finally, the methods are used to analyze the test results, and it is found that the analyzed results with the high precision may be obtained.

Key words: fatigue limit, generalized constant life curve, two-dimensional up-down method