Assessment of the Effect of Pitting Corrosion on Fatigue Crack Initiation in Hydro Turbine Shaft

Abstract

Energy efficiency is a key issue worldwide, and not confined solely to the realm of engineers. Past failures of mechanical power system components must be examined carefully in order to minimise future occurrences and increase energy efficiencies. Improved design procedures have been highly sought by engineers and researchers over the past few decades. The latest verified method with strong application potential within the power industry is that of the Theory of Critical Distances (TCD). TCD is not one method, but a group of methods that have a common feature; the use of a characteristic material length parameter, the critical distance L, for calculating the influence of notch-like stress raisers under static and fatigue loading. A case study from a hydro power plant turbine shaft was chosen to illustrate the development of this methodology. The paper illustrates the application of TCD to the fatigue life assessment of a turbine shaft with stress concentrations due to pitting corrosion.