Abstract: A new model of probability damege tolerance analysis has been presented. It is composed of "a-t" random crack propagating model and probability reliability analysis model which are based on the failure life. The former establishes distribution function of life for arbitrary crack length by using reasonable "a-t" relation and statistically analysing life data for arbitrary given crack length. The latter indicates that safe reliability R of crack population corresponding to given life t * is probability of random critical life exceeding t+. This new model can remedy the weakness of previous analysis model of probability damage tolerance which is composed of "da/dt" random process model and "a-ac" (or K-KC) reliability interference model, and furthermore, it is very convenient to engineering use.

Key words: probability damage tolerance analysis, random crack propagation, reliability