Stochastic Growth of Fatigue Crack under Constant Amplitude Loading

Abstract

The scatter of experimental fatigue crack paths obtained even in very well-controlled constant amplitude loading tests is very large [Virkler et al. 1979, Ghonem & Dore 1986]. The only origin of this uncertainty is some randomness of the material properties which affect the crack propagation process. The fatigue crack growth phenomenon, however, appears to be physically and mechanically so complicated that pure theoretical considerations alone do not suffice to set up a reliable model which could be used to predict the fatigue crack propagation. Nevertheless, the theoretical analysis of the possible mechanisms which are observed to be present during fatigue crack growth points out some relations between crack growth features, material and load characteristics. In order to verify the theoretical investigations and specify the parameters of the proposed models experimental results have to be used. They, moreover, enable us to identify some random characteristics of the model parameters and help us to explain the random nature of the fatigue crack growth phenomenon.