Numerous theoretical models have been developed to predict the fatigue notch factor (also known as the fatigue strength reduction factor); an important parameter in the fatigue life prediction of notched components. These models include: the classical average stress method, the fracture mechanics method, the stress field intensity method, the strain energy method, and the weakest link method. This paper gives a detailed literature review of these methods. It also discusses a recently developed probabilistic method for microstructure -sensitive fatigue notch factor. The probabilistic method provides a very strong physical basis for fatigue strength reduction and the associated notch sensitivity; thus it can be used to determine the effect of notches on reduction of fatigue resistance in a way that directly incorporates microstructure. The results obtained using the new probabilistic framework and other conventional methods are compared with experimental data for notched components.

fatigue notch factor, average stress, fracture mechanics, stress field intensity, probabilistic framework, notch sensitivity.