VIBRATION ANALYSIS OF RAILWAY TRACK WITH MULTIPLE WHEELS ON THE RAIL

The major source of railway rolling noise is the structural vibration of the wheel and rail which is generated by the combination of small-scale undulations (roughnesses) on the wheel and rail contact surfaces. Usually, the rail vibration behaviour is studied using a model in which only a single wheel is present. This is not the case in practice, where multiple wheels roll on the rail. It is shown first that the high-frequency excitation from each wheel can be treated independently by using the superposition principle, provided that the rail vibration is considered as a frequency band average. The appropriate application of the superposition principle is then to model the rail vibration as a sum of cases in which all wheels are retained in contact with the rail but the roughness at all but one of them is set to zero. The presence of multiple wheels on the rail leads to reflections of waves in the rail. The paper explores such effects on the rail vibration caused by multiple wheels acting as supplementary dynamic systems. The receptance of a rail with a single additional wheel on it is studied first to acquire a physical insight into the effects of wheels on the rail vibration. Then more complicated models are developed and used to investigate the effects of multiple wheels on a rail. Practical consequences due to the multiple wheel–rail interactions are also presented.