Comparison of dynamic effects of high-speed traffic load on ballasted track using a simplified two-dimensional and full three-dimensional model

The vertical dynamic actions transmitted by railway vehicles to the ballasted track infrastructure are evaluated taking into account models with different degrees of detail. In particular, this matter has been studied from a two-dimensional finite-element model to a fully coupled three-dimensional multibody finite-element model. The vehicle and track are coupled via a nonlinear Hertz contact mechanism. The method of Lagrange multipliers is used for the contact constraint enforcement between the wheel and rail. Distributed elevation irregularities are generated based on power spectral density distributions, which are taken into account for the interaction. Due to the contact nonlinearities, the numerical simulations are performed in the time domain, using a direct integration method for the transient problem. The results obtained include contact forces, forces transmitted to the infrastructure (sleeper) by railpads, and envelopes of relevant results for several track irregularities and speed ranges. The main contribution of this work is to identify and discuss coincidences and differences between discrete two-dimensional models and continuum three-dimensional models, as well to assess the validity of evaluating the dynamic loading on the track with simplified two-dimensional models.