广义断裂等寿命曲线与二维门槛值概率分布

根据疲劳等寿命曲线思想,首次提出广义断裂等寿命ΔKth-Kmth曲线概念及其表达式,该公式具有明确的物理意义,并能合理表达疲劳裂纹扩展门槛值均值与幅值之间的关系,用以确定二维门槛值概率分布;根据相关系数优化法建立了该公式的参数估计方法,并给出了具有可靠度p的广义断裂等寿命p-ΔKth-Kmth曲线公式,以广义p-ΔKth-Kmth曲线为基础首次导出了二维断裂门槛值概率分布,最后,分别以LY11和40CrNiMoA材料为研究对象,各进行了3组不同应力均值下的门槛值试验,并运用该方法对上述试验结果进行了可靠性分析,发现精度良好.

Generalized Fracture Constant Life Curve and Two Dimensional Probability Distribution of Fracture Threshold Value

Based on fatigue constant life curve, the concept and the universal expression of a generalized fracture constant life curve are presented to determined the two-dimensional probability distribution of the fracture threshold value,by victue of the clear physical significance of the expression and the reasonable relation between the mean and the amplitude of the fracture threshold value. With the optimization method of the correlation coefficient, the parameter estimation formulas of the constant life curve are induced,the generalized fracture constant life p-ΔK_th-K_mth curve with the reliability level p is given. From p-ΔK_th-K_mth curve, the two-dimensional probability distribution of the fracture threshold value is derived. Then, LY11 and 40CrNiMoA are respectively tested under three different average stress, the aforementioned method is applied to analyze the test results,and it is found that a high precision is obtained with the above approaches.