(b)
Fig.2. (a) Dimensions (in mm) of fatigue specimens.(b) Photograph of fatigue test set-up.
The S-N curve which accurately reflected the fatigue properties of materials was a necessary prerequisite for the life estimation of structural components [34].Some empirical models, such as two-parameter powers or exponents, were widely used. The fatigue curve DC51D+Z material was a curve describing the relationship between its stress level and fatigue life, which was approximate to a straight line in logS-logN coordinates. Therefore, in this paper, the exponential function formula was selected to represent the DC51D+Z curve as: