Influence of rail weld irregularity on dynamic stress of bogie frame based on vehicle-track rigid-flexible coupled model

To examine the effects of rail weld irregularity on the dynamic stress of the bogie frame, a numerical model which considers the bogie frame flexibility is established. Field measurements were conducted to validate the reliability of the proposed model and the bogie frame's modal vibration including the bending deformation of cross beams at 50 Hz can be observed. A comparison between the flexible bogie frame model and the traditional multi-body dynamics model is conducted to investigate the influences of the bogie frame's flexibility on wheel-rail interactions. Then the numerical model of the rail weld joint is proposed to study the P2 resonance performance and the dynamic stress patterns of the bogie frame. A comparison of influences with different rail weld irregularities and parameter studies are conducted. Then the effects of fastener stiffness on P2 resonance frequencies are discussed. The results show that it is necessary to consider the bogie frame's flexibility in simulations which will aggravate the wheel-rail vibrations. The short wavelengths in combination with a certain speed could induce the bogie frame's modal vibration and large track supporting stiffness will threaten the running safety of the vehicle which may also contribute to the formation of wheel out-of-roundness. Besides, the limit values of the rail weld irregularities are discussed to provide a reference for rail surface grinding from different aspects.