正火45钢切口件变幅载荷下疲劳寿命及其概率分布估算

Prediction of Fatigue Life of a Medium-Carbon Normalized Steel under Variable Amplitude Loading

通过正火45钢的超载试验及变幅疲劳试验，进一步验证文献［1，2］所提出的变幅载荷下疲劳寿命及其概率分布预测方法的适用性。试验及分析表明，正火45钢切口件的超载效应因子Z＝0，从而在变幅疲劳寿命估算时可不必考虑载荷顺序效应，而直接采用Miner法则和恒幅载荷下的疲劳寿命曲线表达式进行估算，且试验结果与估算结果符合很好，该法可用于结构可靠性评估。

Overloading tests and fatigue tests of 45 normalized steel under variable amplitude load ing were carried out in the present study to further check wheather the procedures developed in ref. [1,2] were generally applicable for predicting the fatigue life and it's probability distribution under variable amplitude loading or not. Test results and analysis have shown that the overloading effect factor Z of 45 normalized steel is equal to zero and thus the effect of loading sequence needs not be considered in life prediction. The fatigue life of 45 normalized steel under variable amplitude loading can be directly pre dicted by using the Miner's rule and the expressions of fatigue life under constant amplitude loading. The procedure[1,2] can be used to assess the fatigue reliability of structures