| Summary: | 博士 === 國立臺灣大學 === 機械工程學研究所 === 93 === Dynamic behavior of railway vehicles affects the maintenance and safety of the railway system. With a view to understanding the dynamic behavior of vehicles, a railway vehicle system dynamic model is developed and discussed in detail based on experimentally measured data. The model consists of a full-vehicle with 28-degree-of-freedom, and some quantities such as conicity, track irregularity and creep force are considered. The model is validated using two sets of field test results of a certain type of vehicle, one dealing with vehicle stability and the other dealing with ride quality. For the stability analysis, the critical speed of the studied vehicle is found to be around 145 km/h. It is also found that the simulation result is in good agreement with the test data. Both of them indicate the transverse acceleration of the bogie meets the required stability criteria set by authorities of the mass rapid transit vehicle systems. As for the ride quality, comparison is also made between the simulation results and test data. Both results show that the resonant frequency of the studied vehicle is around 0.7 Hz, and the one-third octave RMS acceleration curves of the vehicle in all studied cases meet the ride quality criteria set for the mass rapid transit vehicle systems. The impact load due to wheelflat is also studied based on the same dynamic model. The results show reducing the wheelflat to a certain level significantly reduces the risk of derailment. Influences of system parameters on the impact loads due to wheelflat are investigated as well. The results show that wheelflat depth, loading condition and vehicle speed are important factors affecting the wheel/rail impact loads. Finally, the dynamics of a railway vehicle when passing a turnout crossing is studied. The result indicates that decrease of wheel size and/or increase of vehicle speed all lead to increase of the wheel/rail impact force. For example, the increase of vehicle speed from 30 km/h to 80 km/h results in as much as 800 kN increase of the impact force. However, the influence of gap width on impact force only appears when the vehicle runs in high speed.
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