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.