Influence of track and vehicle wheel damages in the train running safety

Resumo

Train running safety is an important concern because although many derailments are minor in terms of
fatalities, all result in temporary rail operation disruption and they are a potentially serious hazard. Running safety
is evaluated by three safety criteria based on factors related to the vehicle contact forces: the Nadal criterion, the
Prud’Homme criterion and the Unloading criterion. Several research studies have focused on the assessment of
the derailment risk based on monitoring measurements but as it is influenced by the existence of various conditions
and environments in which the train is running, it is important to identify the factors that most influence derailment
risk. In this research, the unloading criterion is used to analyze the influence of track irregularities and wheel
defects such as flats, polygonization in the train running safety. The research relies on train-track dynamic
responses obtained by numerical simulations. A freight train and a ballasted track are considered. A 3D wheel–
rail contact model couples the train to the track by using the Hertzian theory to compute normal contact forces and
tangential forces caused by rolling friction creep. The results are promising for the research purposes.