Cracks in Railway Wheels under Rolling Contact Load

Crack initiation and crack propagation in the contact region of a railway wheel are studied by use of analytical and numerical methods assuming a Hertzian contact pressure without and with friction. Triaxial contact and residual stresses are considered in a 3-0 model for crack initiation. Crack propagation is considered in a simplified model mainly involving mode II cracks. Stress intensity factors are computed for plane conditions only. The numerical results obtained are compared with experimentally found threshold values for a real wheel material. Observed cracks in wheels exposed to service loads are investigated and the allowable size of such defects are discussed.