Evaluation of Service-induced Residual Stresses in Railroad Commuter Car Wheels

Analyses of the effects of service conditions on the distribution of residual stresses in railroad commuter car wheels are presented. Novel software has been applied to estimate the effects of service conditions on the as-manufactured state of these wheels. Contact loads resulting from wheel and rail interaction and thermal loads from on-tread braking are considered. Results indicate that contact stresses acting alone result in increased net rim hoop compression. However, thermal stresses due to frictional heating reverse the as-manufactured residual compressive state. In particular, high-performance stop braking may result in large net hoop tension in the rim. When contact and thermal loads interact, the effects of braking dominate the process. The presence of tensile residual hoop stress at the wheel tread has been shown to favor the formation and growth of fatigue cracks, threatening the safety of train operations. The paper provides a description of the analytical methodology and results of its application to a representative class of commuter service. Comparisons of the predicted depth of rim stress reversal with the thermal cracking observed in the wheels of this fleet provides confidence in the ability of the technique to assess the likelihood of thermal crack development in other types of commuter operations and in railroad freight service.