Experimental and numerical modal analyses of high-speed train wheelsets

Abstract

The frequency responses of the wheelsets of a high-speed train are believed to have an important influence on wheel/rail dynamics. This paper is focused on an experimental modal analysis (EMA) and numerical modal analysis (NMA) of a motor wheelset and a trailer wheelset with a hollow-drilled shaft that are both utilized on high-speed trains. The EMA investigation of high-speed train wheelsets is achieved by using a hammer-impact excitation method and a varied-time-base (VTB) technique that has a high identification precision. The NMA is performed using the finite element method to model equivalent spring unit connections among jointed components. The results obtained in the NMA studies are in excellent agreement with those obtained from the EMA studies. Furthermore, NMA is also performed for the case of pre-stressed wheelsets; this is achieved by considering their stress states under a static axle load and a gyroscopic force mimicking operating conditions. Compared with free wheelsets, the results for the preloaded wheelsets have slightly higher eigenfrequencies. In addition, the results obtained in the NMA show the influence of the flexibility of the wheels on the total structural flexibility of the wheelset. Finally, it is expected that the VTB technique can be generalized for use in examining the wheelsets on general rolling-stock.