含凹坑缺陷结构疲劳寿命的快速估算方法

A fast approach for fatigue life estimation of structure with pit defect

基于Miner线性累积损伤理论,探讨了含凹坑缺陷结构使用系数与相应的无缺陷结构使用系数之间的计算关系。在S-N曲线数据拟合的基础上,推导了许用循环次数的比值计算式,并以核压力容器常用材料为例,给出了计算式待定常数的取值及适用范围。形成的疲劳寿命估算方法,为含凹坑缺陷结构的快速疲劳分析及评定提供了一种参考方法。

Background： The appearance of smooth pit defect brings considerable difficulties to the prediction of fatigue life of structure whilst the traditional approach of fatigue analysis hardly meets the requirements of engineering applications. Purpose： This study aims to find a fast approach for fatigue life estimation of structure with pit defeat for engineering applications. Methods： Based on Miner linear cumulative damage rule, the quantitative relation between usage factor of structure with pit defect and that of structure without pit defect is determined. Based on the data fitting of the S-N curve, the expressions of ratio of the permissible number of cycles are deduced, and the range of application is given for common materials of nuclear pressure vessel. Results： Computional results using above mentioned approach provide the codomain of undetermined constants and sphere of application. Conclusion： The approach for fatigue life estimation of structure with pit defect meets the requirements of engineering applications, thus is suitable to fast estimation of fatigue life for nuclear pressure vessel.