基于不同寿命分布的DFR值换算关系

由于使用要求、载荷情况、结构型式与寿命可靠性要求等方面的显著区别,军机结构细节疲劳额定值(DFR,Detail Fatigue Rating)的定义有别于民机结构,主要体现在寿命分布假设与基本可靠性要求的不同以及基本结构的差异上.通过构件疲劳额定系数修正基本结构细节数的差别,假定采用对数正态分布与威布尔分布估计同一结构的中值寿命得到的估计值相同,从而导出了基于不同寿命分布的DFR值换算关系,给出了换算关系取决于DFR基准值与材料类别的结论.为军机结构耐久性设计提供了一种通过民机相似结构DFR值换算确定军机DFR值的方法,最后通过算例进行了验证.

Conversion relation of detail fatigue rating based on different fatigue life distribution

Due to the difference of usage, loading, structure, reliability requirement, and so on, the definition of military aircraft structure detail fatigue rating is different from civil aircraft structure which mainly varies in the fatigue life distribution functions and basic structure. The number of details in different basic structure was corrected by structure component fatigue rating coefficient and estimates of median life was supposed to be the same by log-normal distribution and Weibull distribution. The conversion relation of detail fatigue rating based on different fatigue life distribution was acquired. It is showed that the conversion relation depends on the basic value of DFR and the types of material. An approach was presented for determining military aircraft structure DFR value by the similar structure of civil aircraft and an example was given in the end.