Comparison of Fatigue Strength Calculation Methods for Monobloc Railway Wheels

TEN 13979-1 “Railway applications – Wheelsets and bogies – Monobloc wheels – Technical approval procedure – Part 1: Forged and rolled wheels” approves two types of calculation models for determining fatigue strength – a 3D model and a simplified axially symmetric model with an asymmetric load. Both model types vary considerably, which may affect the results to be achieved. In addition, the determination of the maximum (critical) fatigue cycle amplitude for wheels requires stresses to be analysed at a point during the complete wheel revolution. In the current EN 13979-1 procedures, the amplitude is determined in the place and in the direction with the maximum principal stress without considering changes to stresses at a point for other wheel angular positions. The paper explains methods for strength calculations of monobloc wheels acc. to EN 13979-1. Both standard-approved models for the same wheel were developed and calculated. Differences, advantages and disadvantages of each model were described and the results compared. The complete load cycle for a given point on the wheel body was also analysed and presented. The results of the above analysis were analysed and further research directions were specified to define the actual maximum fatigue load cycle amplitude in railway wheels.