Quantification of stress raiser influence on decrease of machine parts fatigue life

This paper displays the usage of Theory of Critical Distances (TCD) in the prediction of high-cycle fatigue behaviour in machine parts and systems. It is possible to gain real overview of stresses of machine parts by Finite Element Analysis, and to use them as an entry values for application of Theory of Critical Distances. The TCD represents a major extension of linear elastic fracture mechanics, allowing it to be used for short cracks as well as for stress concentrations of arbitrary geometry. Presented methodology is particular valid for machine parts of non-standard dimensions. A particular turbine shaft from hydro power plant was chosen as subject for developed methodology presentation. This paper illustrates the application of the TCD on decrease of fatigue life of turbine shaft due to shaft-flange radii stress concentration and corrosion pits