Application of the theory of critical distances for fatigue life assessment of spur gears

This study evaluates the effectiveness of the theory of critical distances (TCD) method in determining the fatigue lifetime of a spur gear. A comprehensive characterization of the material parameters necessary for critical distance calculation was performed, including the fatigue limit and crack growth threshold, as well as σ-N and ε-N curves for 16MnCr5 steel. A variety of TCD methods were applied to analyse the component, including the point method, line method, volume method, and mesh control. The results indicate that overall, the TCD method is a reliable and accurate way to predict the fatigue lifetime of spur gears. The study reveals a strong correlation between predicted and experimental crack locations and fatigue lifetime, suggesting accurate prediction using TCD and the Smith-Watson-Topper parameter. Although all TCD methods, when applied correctly, yield similar results, mesh control is the faster method and is therefore more attractive from an industrial perspective. The results of this study provide valuable insight for engineers and researchers in the field of fatigue analysis of spur gears and similar mechanical components.