Study on component fatigue-rating factor of structures with similar multi details

The presence of similar multi-details reduces structural fatigue performance significantly. Component-fatigue-rating-factor (R_c) is usually used as modification factor when component fatigue life is estimated with the test result obtained by detail simulation specimens. Based on the assumption that all the details are independent and they follow the same life distribution, two kinds of relationships, one is between R_c and the number of similar details, the other is between R_c and reliability, were established when fatigue life follows log-normal distribution and two-parameter Weibull distribution respectively. The conversion from R_c of fatigue life to that of fatigue strength was discussed. R_c corresponding to typical number of similar details was given. The relationships of R_c with the number of similar details for Aluminium alloy at 2 reliability levels were also illustrated.