Abstract: Detail fatigue rating (DFR) method plays an important role in modern civil aircraft design. To study the sensitivity of the parameters in this method, within the range of slope parameter and dispersion parameter, this paper discusses the errors in the DFR calculation for China-made materials by using Boeing design allowable values, and completes a simple perturbation analysis. After deriving a new Gerber-based DFR equation, this paper compares the results calculated by the new Gerber-based DFR equation with those by Boeing’s DFR equation. The results indicate that of all the parameters in the DFR equation the slope parameter is the most sensitive for calculating DFR. The new Gerber-based DFR equation can be used to obtain the DFR more accurately for ductile materials than the equation presented by Boeing.

Key words: civil aircraft, detail fatigue rating, Weibull distribution, sensitivity analysis, equilife curve