Fatigue Life Assessment of Monobloc Railway Wheels Using S–N (Basquin) Method and Hertzian Contact Analysis

Abstract

The fatigue resistance of a monobloc ER8 steel wheel is evaluated using a stress-life ($\mathrm{S}-\mathrm{N}$) approach based on Basquin’s law, with local stresses calculated through Hertzian contact theory. A fatigue safety factor accounts for uncertainties related to loading conditions and material properties. The predicted number of cycles is converted into equivalent service distances. A wheel with a 445 mm radius and 135 mm tread width is analyzed under representative loads. The tread center is safe up to $5.1 \times 10^{6}$ cycles $(\approx 7120 \mathrm{~km})$, while the edge exhibits the shortest lifespan, approximately 2510 km. The combined approach of Hertzian contact analysis, $\mathrm{S}-\mathrm{N}$ modeling, and a fatigue safety factor provides a reliable methodology for predicting wheel fatigue life and planning maintenance operations.