Dynamic vehicle–track interaction and plastic deformation of rail at rail welds

A numerical model for dynamic vehicle–track interaction at rail welds with longitudinal surface irregularity is presented. In the model, the vehicle and track, except for the rails, are treated as rigid multi-body systems. A Timoshenko beam is used to model the rails which are discretely supported by sleepers. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The model is applied to calculate the dynamic wheel–rail contact forces and the sizes and locations of the contact areas. A three-dimensional finite element model of rail at welds is then built up to investigate the plastic deformation of rail. The contact forces, the sizes and locations of contact areas obtained by the vehicle–track dynamics simulation are utilized as the inputs to finite element model. The influence of different geometries of rail welds on the dynamic wheel–rail contact forces, stresses and deformations of rail is investigated. The analysis reveals that the train speed and the wavelength and wave depth of the irregularities at rail welds have great effects on the wheel–rail contact forces. The dynamic forces due to the welded rail surface irregularity cause increased plastic deformation not only at the rail weld but also at the base metal near the rail weld. The numerical results obtained are very useful in the tolerance design of welded rail surface irregularity.