Residual stresses in railway wheels and their effect on damage rates through the life of a wheel

Wheelset maintenance and renewal comprises a significant portion of the whole-life cost of railway rolling stock. At present, many GB passenger trains have their wheels turned on a lathe at regular intervals to prevent the propagation of Rolling Contact Fatigue (RCF) cracks in the rim. Evidence from a number of fleets suggests that RCF damage occurs much more quickly as the wheelsets near the end of their life. Wheel manufacturing processes are intended to induce a compressive hoop stress in the wheel rim to reduce crack propagation rates. Variations in residual stress through the life of a wheel may
potentially influence the observed damage rates. This paper describes an experiment to measure
residual stresses in new and used wheel rims to identify whether this could be a significant factor. Assuming that the as-manufactured stress distribution was similar for all three wheels, it is found that the stresses are redistributed within the wheel rim during its life as material is removed and plastic flow occurs. However, the hoop stress near the running surface remains compressive.