基于对数正态分布第k试验寿命的分散系数法

Life scatter factor method based on the kth order experimental life with logarithm normal distribution

针对发动机构件寿命试验评估中对寿命分散系数计算公式与不同取值的需求,本文导出了寿命符合对数正态分布、基于任意第k试验寿命分散系数计算公式。并给出置信度为0.95、可靠度为99.87%、母体对数正态标准差lσgN=0.13时的寿命分散系数。本文基于最差试件寿命的分散系数与已有文献一致,而基于最好试件寿命分散系数较已有文献更为合理;采用本文公式可得到任意给定置信度、可靠度、寿命分散条件下的寿命分散系数,可供工程上评估构件寿命时使用。

For the needs of the life scatter factors under different conditions to assess the engine component lives, in this paper, the theoretical formulas of the life scatter factors based on the arbitrary kth order experimental life of a small sample with logarithm normal distribution were deduced. Life scatter factors were given with the confidence of 0.95, the reliability of 0. 9987 and the standard deviation of logarithm normal distribution 0. 13. The life scatter factors based on the worst experimental lives fit well with those in the published literatures. The life scatter factors based on the best experimental lives are more reasonable than those in the literatures. Using the formulae given in the paper, the life scatter factors can be obtained with any given confidence, reliability and standard deviation of the logarithm normal distribution, which can be used to assess component lives in engineering application.