Stochastic Model to Fatigue

A stochastic model is proposed to represent the accumulated damage in a structural element caused by load repetition at a given level of load. The probability distribution of the number of applications necessary to produce fatigue failure is obtained. This is compared with the empirical distributions corresponding to experimental results on aluminum specimens, on prestressed concrete beams, and on short concrete elements. The comparisons are statistically satisfactory. The risk function corresponding to the proposed distribution is monotonically increasing with the number of applications; this eliminates an objectionable feature of other, widely used risk functions.