This investigation demonstrates the wheel wear evolution and related vehicle dynamics of high-speed trains with an operating distance (OD) of around two million kilometres. A long-term experimental test lasting two years was conducted to record the wheel profiles and structural vibrations of various trainsets. The wheel wear, namely the profile shape, worn distribution and wheelset conicity, is investigated for several continuous reprofiling cycles. Typical results are illustrated for the stability analysis, and the ride quality is examined with increasing OD. In addition, the vibration transition characteristics between suspensions are investigated in both the time and frequency domains. The experiments show that the dominant wear concentrates on the nominal rolling radius, and the wear rate increases with OD because of the surface softening resulting from the loss of wheel material. The vibration of structural components is aggravated by the increase of the equivalent conicity of the wheelset, which rises approximately linearly with the wheel wear and OD. High-frequency vibrations arise in the bogie and car body related to the track arrangement and wheel out-of-roundness, causing the ride comfort to worsen significantly. Additionally, the system vibration characteristics are strongly dependent on the atmospheric temperature. Summaries and conclusions are obtained regarding the wheel wear and related vehicle dynamics of high-speed trains over long operating times and distances.

This paper introduces a new type of suspended monorail developed in China with the advantages of both German and Japanese monorails. The FE (finite element) model of the bridge is built in Ansys and coupled with the multibody dynamic model of the vehicle in the UM (Universal Machine). software. FIALA formula is used to construct the tire model. Then, the vehicle-bridge coupling system of the new type suspended monorail is set up and simulated with Park method. The result of the modal analysis and vehicle-bridge coupling simulation draw the same conclusion that the span of the stiffeners could result in the resonance of the vehicle system, which is due to the coupling of the frequencies of the natural modes of the car body and bogie with that for vehicle passing through stiffeners. Through the multibody dynamic simulation of the vehicle-bridge coupling system, the modes of the bridge at the frequencies of 5–10, 15–25 and 30–40 Hz are easily excited when the vehicle passes through the bridge. The three constraint modes and free modes of the bridge are similar in these frequency ranges.

With the continuous development of rail transit industry and the acceleration of train speed, higher requirements are established for the operation quality of high-speed trains and the reliability of transmission system. In the process of train running, speed fluctuation and vibrations from various parts of the driving devices are common, which could be greatly affected by the traction torque. During traction transmission, the harmonic vibration torque exists in traction motor due to that the motor is connected with non-sinusoidal alternating current. In order to study the vibration influence of the electrical component of traction transmission system on the rail vehicles, i.e., bogie and car-body, an electro-mechanical coupling dynamic model for rail transit vehicles was established by explicitly incorporating the electric-induced traction into the transmission model. The dynamics responses of the vertical, lateral and longitudinal acceleration on vehicle components, such as axle box and car-body were quantitative analyzed. By comparison with field test, it was observed that there was a vibration peak of 12-times of the fundamental rotor frequency on the bogie frame and axle box, which existed at conditions of traction, uniform speed and braking. However, the vibration acceleration exhibit nearly little difference with or without traction force, especially at low frequency domain < 100 Hz.

Analysis of the Chongqing monorail shows that there is no relationship between wheel wear and radial force, which means the radial force cannot be used to evaluate the wheel wear of monorail. Due to the same physical significance of the Schallamach tire wear model for automobiles, the wear index of railway wheels, which represents the creep power of unit wheel–rail contact area, is proved to be effective in evaluating the wheel wear of railway vehicles, automobiles, and vehicles with both properties, namely, monorail. Parameters of Chongqing monorail, modified through genetic algorithm, are used to build the model of the articulated monorail. Through co-simulation of the MATLAB and UM software, the wheel wears of two types of articulated monorail are calculated. For both types of monorails, correlation analysis shows that the variation of driving wheel and guide wheel wear of the inner bogies with the track curvature radius are roughly the same. The variation of the wheel wears in the two end bogies is a little different from that of the inner bogies. Comparison indicates that the wheels of the bolster type monorail wear more than that of the non-bolster type. Regardless of the monorail type, the wheels in the inner bogies wear more.

The wheel polygonization has become a great concern for the high speed rail vehicle owing to its highly adverse effects in high speed condition. Such periodic distributed wear along the wheel can give rise to high magnitude of high frequency impact loads at the wheel/rail interface and further contribute to severe fluctuations in axle box acceleration and the self-loosening for axle box bolts. In this study, the wheel polygonization-induced axle box vibrations and bolt self-loosening are thus initially investigated through the field tests and the roller test rig. Subsequently, a coupled vehicle/track dynamic model integrating a typical high speed rail vehicle and a flexible slab track is formulated to identify the mechanism of bolt self-loosening in the presence of wheel polygonization. The results suggest that the wheel polygonization can result in high magnitude accelerations in the axle box, and excite some of vibration modes of the axle box and its end cover. The accelerations on the axle box end cover are much larger than those obtained on the axle box, which is also comparable to the experimental results. It is thus believed that the self-loosening of axle box end cover’s bolts is mainly attributed to the severe oscillations on the axle box due to the wheel polygonization.