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Abstract

Since fatigue is essentially the manifestation of continuous local fracture caused by cyclic stressing, it has been pointed out that fatigue shows the statistical characteristics reflecting the stochastic feature of each fatigue process.Thus, the factors governing this fluctuation can be studied on the basis of both extreme theory and the stochastic process theory.The similar fluctuation also appears in the fatigue crack propagation process, and consequently a number of crack growth curves may be obtained.In this paper, the Monte-Carlo simulation was conducted by assuming the microstructural heterogeneity model as well as the stochastic process model of fatigue crack propagation, and the factors governing the statistical fluctuation in the fatigue crack propagation process were investigated.The results show clearly that such a factor as the difference in resisting power of structure caused by the change in size distribution of structural units like crystal grains, influences considerably the stochastic feature of the fatigue crack propagation process.