Fatigue life prediction of key structural parts in aeronautics and astronautics based on fuzzy theory

For the fuzzy phenomenon during fatigue life prediction of key structural parts in aeronautics and astronautics, membership function is used to denote the fuzziness of fatigue damage caused by the stress nearby fatigue limit. The concept of fuzzy zone of stress is put forward and classified as safety fuzzy zone, economy fuzzy zone and compatibility fuzzy zone according to relative position among fatigue limit and edges of the fuzzy zone of stress. The results of the example show that the accuracy of fatigue life prediction can be largely improved by the method. Choosing safety fuzzy zone and increasing half normal distribution in the example, and setting parameter a = 0.6sigma_r, k = 0.5, the error can be reduced by 51.0% compared to the traditional fatigue life prediction method.