Influence of roughness and wear on pressure distribution and stress state at wheel - rail contact

The rail and wheel surfaces with numerically generated roughness have been incorporated into a computerized analysis model for concentrated contacts. In normal running operations the contacting surfaces undergo very complex loading regimes characterized by: the lack of lubrication, existence of normal, tangential and traction loads with the presence of different degrees of slippage. An inevitable wear evolves that determines time dependencies for profiles of active surfaces The role played by the running in process as well as the main roughness parameters on the pressures distribution, contact area and depth distribution of von Mises equivalent stress, have been pointed out. Important criteria as the traffic safety and maintenance costs require optimized profiles. To fulfill this requirement the knowledge of wear evolution becomes a priority and consequently the contact areas and pressures distributions corresponing to different stages of wear is one of the primary needs. The profiles measurements of new and worn wheels revield the modification in pressures distribuion, contact areas and vonMises stresses caused by time evolutuon of wear.