基于局部应力应变法估算高周疲劳寿命

以往用局部应力应变法计算结构高周疲劳寿命不好的主要原因是在损伤与寿命计算中没有考虑缺口应力梯度等的影响。文中利用疲劳缺口系数对应变－寿命曲线的弹性分量进行修正，从而可以较好地反映缺口根部应力梯度等对疲劳寿命的影响，使得局部应力应变法不仅可适用于低周疲劳寿命分析，也用可以用于高周疲劳寿命分析。文中给出的方法简单，精度了，便于工程应用。

High-Cycle Fatigue Life Prediction Based on Local Stress-Strain Method

As we know, it is very hard to get an accepted accuracy in high cycle fatigue life prediction by the local stress strain method. The main reason is that the effect of stress gradient on fatigue life is not suitably taken into consideration in the previous work. The effect of stress gradient on fatigue life is considered in fatigue damage analysis instead of in local stress strain analysis. Fatigue notch factor is used to modify the elastic component of strain fatigue life curve in order to take into account of the effect. A modified strain fatigue life curve is obtained. Case studies show that the local stress strain method is suitable for predicting not only medium/low cycle fatigue life, but also high cycle fatigue life in terms of the modified strain life curve and the corresponding approach. It is easy to use this approach with a good accuracy in fatigue crack initiation life prediction of engineering materials and structures.