Research on determination of civil aircraft material properties sample distribution for design allowable computation

The design allowable of materials is an important index of the mechanical properties of civil aircraft materials, and relative computation bases on the distribution assumption and the corresponding distribution. According to the computation, the results of the same sample with different distribution math-models are obviously different, so it is necessary to determine the distribution by fitting the distribution of samples in order to calculate the allowable value. This paper discusses the method of determining the fitting result by introducing P-P plot and R-square when the material property data sample passes the Anderson darling fitting test for two or more distributions under corresponding confidence level. The results show that when the sample size is low, the P-P plot and the r square can provide reference information to determine the best fitting results, especially when the sample obeys Weibull distribution.