Comparison of modern track modelling concepts in multi-body simulation and their application for short-wave rail surface geometries

Geometric irregularities on rail surfaces increase dynamic forces in wheel-rail contact, causing damage and wear to track and vehicle components. Multi-body simulation is a practical tool for optimizing the rail-wheel system. The choice of excitation type and the multi-body model significantly impact the accuracy of the results and computational efficiency. Rigid-body models with moving sleepers are commonly used in the dynamic analysis of railway vehicles. On the other hand, flexible multi-body models with finite element (FE) rails, incorporate track flexibility. This study shows that multi-body models with FE components offer advantages in capturing the dynamic behaviour of vehicles on realistic tracks, especially when the effects of short-wave track irregularities are taken into account, but the computational effort increases significantly. For the investigation of ballast damage, a rigid body model with multiple masses offers a good compromise between computational effort and the quality of results. It covers a frequency range up to 150 Hz and represents the loads in what is known as the P2 force range well with 2% to 8% deviations from the measured values. For higher frequencies, flexible FE bodies are required that can cover frequencies up to 1000 Hz and primarily lead to damage to the rail surface.