疲劳寿命分散系数的确定与应用研究

疲劳寿命分散系数是评估飞机结构疲劳寿命与航空发动机轮盘寿命试验的重要技术参数之一。阐述了国内外疲劳寿命分散系数研究的成果,针对工程中实际寿命分布问题中最常见的对数正态分布和威布尔分布的形式,给出了基于试验样本最差、中值、最好及第k试验寿命的分散系数表达式;重点分析总结对数正态分布标准差和威布尔分布中形状参数的选取,同应力多危险部位分散系数研究及其随应力的变化规律;通过2个例子分析了疲劳分散系数在轮盘低循环疲劳寿命工程计算中的应用,认为疲劳寿命分散系数应在不同温度和应变比,对数正态分布标准差,同应力多危险部位,3参数的威布尔分布,工程化应用等方面开展进一步研究。

Determination and Application of Fatigue Scatter Factors

Fatigue life scatter factor is one of the key technical parameters for aircraft parts fatigue life and aeroengine disk life experimental assessment. The development of fatigue life scatter factors was reviewed. Aiming at the logarithm-normal distribution and the Weibull distribution commonly used in engineering, the theoretical formulas of the life scatter factor based on the worst, median and the best experimental lives were given. A particular focus was placed on the analysis of selecting of the standard deviation of logarithm-normaldistribution and the shape parameters of Weibull distribution, and on the research of scatter factor of multi same-stress critical sites, the lawof scatter factor versus test stress. Two examples illustrated the engineering application of life scatter factor determination in disk low cycle fatigue. The results show that the fatigue life scatter factor investigation in combine with the future research focus on the areas such as different temperature and strain, standard deviation of logarithm-normal distribution, multi same-stress critical sites, three parameter Weibull distribution, and engineering application should be conducted.