A study on lifetime of a railway axle subjected to grinding

For security requirements, no fatigue failure of axles is admitted in railway industry. Design process of axles must ensure that there is no crack initiation during its life. Maintenance inspections guarantee that no defect initiates critical propagation of fatigue cracks. In order to remove surface defects, wheel grinding is realized during maintenance task. The present paper addresses a lifetime comparative study of an axle with and without grinding operation. The goal is to investigate the influence of the grinding parameters on the lifetime of axle. In the first part of the paper, the context of maintenance of railway axle is briefly described and the grinding process is presented. The grinding process modifies the roughness, the microstructure of the surface and induces residual stresses: some experimental results are presented. In the second part, the case of a ground axle is considered without defect. A study of the effect of the grinding process on the lifetime of fatigue samples is presented. In the third part, the case of a ground axle is considered with defects. In this case, a study of the effect of the grinding process on the lifetime is presented for different types of defects. Fatigue tests results on specimens are presented. Numerical simulations results for lifetime evaluation are also presented.