Abstract
Increasing safety requirements of structures induces necessity of taking into consideration the random nature of variables in the fatigue design. Fatigue analysis of real structures in connection with probabilistic analysis needs a big computational effort. In this paper a new approach and methodology to fatigue analysis of structures using fuzzy numbers are presented. The method has been developed. A new efficient tool of fatigue analysis was created. The calculation of fatigue life using fuzzy numbers set is illustrated with analysis of hydraulic cylinders. Local fatigue approach is used at critical locations on hydraulic cylinders. The purpose of the probabilistic design is to estimate the probability of failure for critical locations on hydraulic cylinder.