PLASTIC-FLOW AND SHAKEDOWN OF THE RAIL SURFACE IN REPEATED WHEEL RAIL CONTACT

Recent progress in modelling the near-surface plastic deformation caused by repeated wheel-rail contact is reported. A simple non-linear kinematic hardening law is described which is capable of predicting the response of rail steel to sliding contact loading. This hardening law is incorporated into a theory of elastic-plastic sliding contact. Particular attention is paid to the deformation at the surface caused by high tractive loads, since this appears to be the most common form of deformation leading to wear and fatigue of railway track. Shakedown limits are calculated for various combinations of contact loading relevant to railway practice, and an approximate technique is used to calculate the plastic flow that occurs when the shakedown limit is exceeded. The predictions of the theory are compared with experimental measurements of plastic flow in disks.