Linear Elastic Fracture Mechanics (LEFM) concepts are widely used to characterize the crack growth behavior of materials under cyclic stresses in different environmental conditions. It is important to note that both pitting theory and crack growth theory have been used in the model development as follows. Pit growth rate theory proposed by Godard is combined with the fatigue crack growth concepts. The time (or cycles or both) to nucleate a Mode I crack from a pit (under cyclic loading) could be modeled using LEFM concepts. Based on this idea, a few models [41, 47-49] were proposed. All of the models assume hemispherical geometry for the pit shape and the corresponding stress intensity relation is used to determine the critical pit depth using the crack growth threshold (DKth) that is found empirically. For a hemispherical pit geometry, these models provide "a reasonable estimate" for the total corrosion fatigue life. Details of these models are presented in Table 2. The applicability of the proposed pitting corrosion Fatigue Models in practical cases is discussed in the next section.
See also: Boundary element modeling,Corrosion models, Knowledge based models, Mechanistic models, Pitting fatigue models, Risk based models
Review of Pitting Corrosion Fatigue Models, D.W. Hoeppner, V. Chandrasekaran, and A.M.H. Taylor, University of Utah and FASIDE International Inc.