A Stochastic Model for Crack Initiation and Fatigue Life

A stochastic theory of high cycle fatigue life is based on a combination of the theory of diffusion in the presence of a stress field with activated state theory. The result is expressed in terms of three empirical parameters which are related to four microscopic quantities. An infinite life stress limit is obtained for certain values of the parameters, and the shape of traditional 'S-N' plots is reproduced. The theory is used to fit data from open-hole specimens tested in a joint Alcoa - Air Force program.