压力容器裂纹疲劳寿命预测的Pairs公式材料常数的相关性分析

介绍了计算疲劳裂纹亚临界扩展速率中常用的Pairs公式、最小二乘法的一般原理和相关系数r的概念。以07MnCrMoVR钢为例运用最小二乘法得出了lgC和m的线性关系,并利用相关系数r判断其相关程度,得出了两者具有极强相关性的结论。基于Pairs公式中材料常数m服从正态分布这一知识,利用lgC和m的线性关系以及正态分布的相关知识,参考压力容器安全评估的方法,探讨了对疲劳裂纹的亚临界扩展速率和疲劳寿命近似预测的方法。

Correlation Analysis of the Material Coefficient in Pairs Formula for Predicting the Fatigue Lifetime of the Cracks of Pressure Vessels

The frequently-used Pairs formula,general principle of least square method,and concept of correlation coefficient r for calculating the subcritical propagation rate of fatigue cracks were presented.The linear relation between lgC and m was derived using least square method based on the sample of 07MnCrMoVR steel,the relative degree of lgC and m was judged using the relative coefficient r,it was concluded that they both were strongly related to each other.An approximate prediction method of the subcritical propagation of fatigue cracks was discussed based on the knowledge that material coefficient m in Pairs formula submitted to normal distribution using the linear relation of lgC and m,relative knowledge of normal distribution,and safety evaluation method of pressure vessels.