Rail transportation is regarded as a reliable, quick, and secure mode of transportation. The wheel-rail contact interaction is crucial to the railway operation since it is responsible for supporting, traction, braking, and steering of railway vehicles. Improper wheel-rail interactions may produce or exacerbate wheel-rail interface issues such as rolling contact fatigue (RCF) and wear, which can threaten the vehicle’s running safety and stability. A review of the evolution and recent literature on wheel-rail contact mechanics and tribology is presented here. Topics covered include the basics of wheel-rail contact problem and methodologies for modeling both the normal contact (Hertzian and non-Hertzian) and tangential contact (Kalker’s theories including CONTACT and FASTSIM algorithms, Polach’s theory, USETAB program, etc.). The paper also reviewed various effects of contaminants and environmental conditions (water, leaves, sand, temperature, humidity, etc.) in wheel-rail contact. Various wheel-rail empirical adhesion models like the Water-induced low adhesion creep force model (WILAC) model and adhesion models based on elastohydrodynamic lubrication (EHL) theory (Greenwood-Tripp [GT] and Greenwood-Williamson [GW] models) are also reviewed. Lastly, the paper discusses the need and challenges for developing and integrating the wheel-rail non-Hertz contact model and adhesion model, as well as open areas for further research.

Vehicle wind speed measurement has always been a vital issue when assessing the aerodynamic performance of a high-speed train in cross winds. Conventional anemometers are not applicable in the extreme environment caused by trains. In this work, a new wind speed measurement method is proposed, and a cylindrical anemometer to simultaneously measure the wind speed and direction is presented. The instrument consists of a cylinder with 12 evenly distributed holes that connect to 12 differential pressure sensors. Thus, the pressure distribution developed by the wind on the lateral surface of the cylinder is obtained. Then, theoretical relations among 3 neighboring pressure maxima and the wind speed and wind direction are formulated and validated with a wind tunnel test, where the fabricated anemometer is rotated at 10° intervals under a wind speed of 5-60 m/s. Field tests are conducted to assess the environmental adaptability of the proposed anemometer. The experimental results show that the proposed method and developed anemometer can be applied for air flow measurements and have high accuracy, reliability and durability.

Structured grinding wheel has obvious advantages in reducing grinding force, and the structural parameters of grinding wheel have important influence on the reduction of grinding force. In order to determine the influence law of structural parameters on grinding force, the following theoretical modeling and experimental research work are carried out in this paper. Firstly, single grit scratching experiments of the workpiece material are carried out to determine the critical cutting depth for ploughing and cutting transition. The influences of structural parameters on the maximum undeformed chip thickness and the average contact arc length during grinding are analyzed in detail. The abrasive grains are simplified into a cone with an apex angle of 120°, the surface topography model of the structured grinding wheel is established according to the measured results of the distribution law of abrasive grains on the surface of the grinding wheel and the structural characteristic parameters. Combined with the grinding force model of single abrasive grain in ploughing and cutting stages, the grinding force calculation model of straight groove structured grinding wheel is established during the grinding process. Finally, grinding experiments are carried out to verify the accuracy of the theoretical grinding force model. The results show that the calculated values of grinding force are in good agreement with the experimental values, and the maximum calculation errors of tangential grinding force and normal grinding force are 14.5% and 11.8%, respectively. It is found that when the intermittent ratio of structured grinding wheel is constant, the groove width has little influence on grinding force. However, when the groove width is constant, the intermittent ratio has a great influence on the grinding force, and with the increase of the intermittent ratio, the grinding force decreases obviously.