介绍了S-N曲线的一般数学表达形式。将最常用的幂函数表达式Sm·N=C变换成了标准幂函数形式S=C1/m·N-1/m,用该式和标准幂函数式S=C·Nn拟合处理了三种材料焊接接头的疲劳试验数据。对处理结果的比较发现,拟合处理方法不同,得到的S-N曲线的具体表达式也完全不同。按前式拟合得到标准离差比后者普遍偏大,根据该曲线方程确定的条件疲劳强度比后者普遍偏小。为工程应用中进行疲劳设计时,对S-N曲线方程拟合方法的选择提供了依据。

General mathematical expressions for S-N curve were introduced. The most used power function Sm·N=C expression was transformed into the standard power law expression S=C1/m·N -1/m. Fatigue data for three materials of weld joints were processed according to the expression and standard power function relation S=C·Nn. The results were compared and it manifested that different disposing methods would result in completely different S-N expression. Standard deviation was bigger but conditional fatigue limit was smaller derived from the former power law expression than the latter,which would provide reference for fatigue design to select S-N expression in engineering application.