A new type of RCF, experimental investigations and theoretical modelling

For a new type of rolling contact fatigue (RCF) (Belgrospi) an explanation has been found by an approach closely combining experimental and theoretical investigations. This new type of RCF has firstly been observed on high speed lines in wide curves. The speed on those locations exceeded 200 km/h. Cracks occurred in nests periodically spread along the rail tread. These nests are grouped to the peaks of the slight corrugation found on the rail tread. Thorough measurements have been performed to assess the track site and its corresponding parameters. These measurement have been used to validate the simulation models applied in the theoretical investigations and to assess the exact features of the RCF like position of the cracks with respect to corrugation, position relative to the gauge corner, corrugation wavelength, crack depth, etc. Simulations applied have been the prediction of the vehicle running dynamics to identify the exact contact situation, position, geometry and load. These parameters then have been used in the prediction of contact forces and contact stress distribution caused by the vehicle rolling over corrugated rail tread. The simulation tools applied are SFE AKUSRAIL for the prediction of the vehicle track interaction, here prediction of corrugation growth, contact forces and stresses, in the medium to high frequency range. For the simulation of the vehicle running dynamics the ADAMS Rail solver MEDYNA has been used. The simulation indicated that a change in the maintenance routine (rail grinding) would be most promising and cost-effective.