| Due to the continuous development of the axle load of the locomotive and vehicles, wheel/rail wear becomes severe increasingly. Besides, wheel/rail wear directly influences on the system dynamic performance and wheel/rail force of locomotive. This leads to a massive influence on the lifetime of the wheel, safety and stability of locomotive operation. As a result, the locomotive operating maintenance costs will be significantly increased. Hence, it has great significance to carry out the research of the wheel wear of locomotive.In view of this, in order to study the wheel wear law, taking the Co-Co type diesel locomotive which is running in Vietnam’s railway line as the research object, the wheel wear of locomotive was simulated based on locomotive system dynamics model, the wrheel/rail rolling contact theory, combined with the wheel wear model, and analyzed the effect of railway parameters, locomotive parameters and operating conditions on the wheel wear for the sake of providing the certain theory reference to reduce the wheel wear of locomotive.At fisrt, considering the basic structure of Co-Co type diesel locomotive, the locomotive-track coupling dynamic model was set up in this theis, all the movement parts were analyzed in the detail to set up the vibration equations. The locomotive dynamical model was built by SIMPACK software, the primary and secondary suspension system of locomotive and the connected relation between the components were considered in this model.Wheel/rail rolling contact is an important part of the locomotive vehicle system dynamics analysis in the dynamic calculation model. Wheel/rail normal and tangential contact theory were presented. Based on the contact patch area and maximum of contact stress, the Hertzian and semi Hertzian theories were taken into compared with CONTACT program. Obtained results show that results calculated by semi Hertzian model has good consistency with CONTACT program’s than that by Hertzian model. Thus, the semi Hertzian theory and FASTSIM algorithm based on semi Hertzian theory were adopted to model normal contact and tangential contact problem of wheel/rail contact calculation in the thesis.The Zobory, Braghin models were presented in detail. The wheel wear calculated by Zobory model and Braghin model. The FFT lowpass filtering method was utilized to smooth and its result was evaluated, this methods can reflect the characteristic of original data. The wheel wear depth reaches 0.1 mm as the condition of wheel tread wear updating. Simulation results were compared with the measured results. Obtained results show that the wheel wear calculated by Zobory model and Braghin model have the certain error in compared with the measured results, but that by Zobory model is more close to the measured results. Therefore, Zobory model was adopted to wheel wear research. The study also modified Zobory model in order to assure the simulation results more accurate. The modified model and the corresponding numerical program were applied to simulate the wheel wear depth and distribution law of locomotive, and the running mileage of the wheel wear limitation was also predicted.In order to verify the correctness and reliability of the revised wear simulation model calculation results, based on theories of mathematical statistics, combined with the measured wheel wear data, a model to predict the turning period was established, and calculation program was compiled. According to the different reliability, running mileage of the wheel wear limitation of the locomotive was predicted. Predicted results were taken into compared with the revised simulative results, results show that the modified wear model has good consistency with the turning period model based on the measured data, so the modified wear model can reflect the actual measured data.The influence of railway, locomotive parameters and operating conditions on the wheel wear were analyzed by using the modified wear model. Obtained results show that the wheel wear depth increases with the decrease of curve radius. When the railway grade is improved, wheel wear will be reduced. The increase of rail gauge will reduce the wheel wear depth. From reducing abrasion wheel point of view, the 1/40 rail cant can effectively reduce the wheel wear whens the ML20 wheel profile and the P43 rail profile matched. The P50 rail profile can effectively reduce the wheel wear rather than the P43 rail profile. The wheel wear depth and distribution range increase with the increase of velocity. The wear depth obviously increases with the increase of axle load. The wheel wear depth has a decreasing tendency with the increase of wheel diameter. When the wheelbase is reduced properly, the wheel wear will be decreased certainly. For the D20E locomotive bogie type, the primary vertical stiffness slightly influences on the wheel wear, but the primary longitudinal and primary lateral stiffnesss significantly influence on the wheel wear. When the friction coefficient is properly decreased, the wheel wear is reduced, the wheel wear reduced obviouslv when friction coefficient is 0.1. |
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