An alternative method to include track irregularities in railway vehicle dynamic analyses

The dynamic behaviour of the railway vehicles dependents on the interaction that is developed between the wheels of the rolling stock and the rails. Furthermore, one of the most sensible issues in the railway industry is the damage on vehicles caused by the track conditions and the infrastructure deterioration due to the trainsets' operation. The study of such phenomena requires the accurate definition of the track geometry that involves, not only the representation of the design track layout, but also the description of its irregularities. In this work, a methodology that includes the track imperfections, measured experimentally by the railroad companies, in the definition of the track model is developed. The purpose is to obtain realistic representations of the track, which are essential to study the dynamics of railway vehicles. The methodology described in this work is applied to study the influence of the track irregularities on the dynamic behaviour of the railway vehicle ML 95, which is operated by the Lisbon metro company. For this purpose, a multibody formulation is used to build the vehicle model and a generic wheel-rail contact formulation is applied in order to determine, online during the dynamic analysis, the contact points location and the respective normal and tangential forces. The studies are performed in real operation conditions when travelling between two of the metro stations. The accuracy and suitability of the methodology presented here is demonstrated through the comparison of the dynamic analysis results against those obtained by experimental testing.