ABSTRACT
The subject addressed in this paper concerns the constantly developing methods of determining the fatigue strength of industrial pipelines. The description of semi-elliptical crack propagation proposed in the paper applies a deterministic model based on a modified Paris’ formula, which became the basis for developing a probabilistic model, being the subject of this publication. Based on a differential equation, a Fokker-Plank parabolic partial equation was derived, which describes a crack development in a probabilistic sense, at the same time taking into account deterministic model relationships. A solution of the equation is a two-dimensional normal distribution of crack propagations. A manner of estimating the distribution parameters is also stated. Having a distribution of probability with known parameters, in the case of an assumed probability of exceeding the permissible crack length, the fatigue life of model elements cut-out from industrial pipelines was estimated.
