“…Вкочування гребеня колеса на головку рейки або вістряка з подальшим провалом іншого колеса всередину колії найбільш імовірне в порожніх вагонах у кривих та навіть прямих ділянках колії, коли вагон витискається під час гальмування поїзда вгору й одночасно встановлюється в «ялинку» під дією набігаючих незагальмованих вагонів. Поперечна сила, яка при цьому виникає, притискає гребінь колеса до зношеної бокової грані головки рейки, а за наявності навіть незначного повороту рейки гребінь колеса по похилій площині бокової грані вкочується спочатку на головку рейки, а через кілька метрів зістрибує з рейки на шпали і далі на баластну призму [10,13,23].…”
Purpose. The work is aimed at determining the influence of the lateral displacement of a freight car bogie, taking into account the value of the movement speed on its main dynamic indicators and interaction indicators of the rolling stock and the track. Methodology. The quantitative assessment of dynamic indicators was obtained by the method of mathematical and computer modeling. The design scheme of the car takes into account the interaction peculiarities of cars as part of the train: the possibility of all modes of body vibration in space, the transmission of longitudinal force from neighboring cars in vertical and horizontal directions, taking into account the technical condition of individual parts of the car and their design features, as well as various operating conditions. Findings. During the research, a mathematical model of a coupling of five freight cars was applied to study the dynamic loading of a gondola car and a track. Main dynamic and interaction indicators of the rolling stock and the track in case of transverse bogie displacement when moving along curved track sections assessment were assessed. The maximum possible values of the lateral displacement of the freight car bogie were substantiated. Originality. The mathematical model of the coupling of freight cars in the train has been improved. In the calculation schemes describing the vibrations of the cars, the peculiarities of the freight car bogies, lozenging of the bogie side frames are taken into account. The model makes it possible to study the effect of changing rotation angle of the central axis of the car body, which in turn leads to the lateral displacement of bogies relative to each other, on the main dynamic and interaction indicators of the rolling stock and the track. For the first time, the influence of transverse displacement of the bogie was investigated, taking into account the wear of its parts and assemblies when moving on track sections with unevenness. Practical value. The calculation results can be used to assess the influence of the bogie transverse displacement on the dynamic qualities of the rolling stock and interaction indicators of the rolling stock and the track, taking into account the wear of parts and units of the bogie when moving in straight and curved track sections with irregularities. The application of the results obtained will contribute to an increase in the stability of freight rolling stock in the conditions of increasing travel speeds, which in turn will allow developing technical conditions for the implementation of resource-saving technologies for transporting goods that meet the safety requirements of train traffic.
“…Вкочування гребеня колеса на головку рейки або вістряка з подальшим провалом іншого колеса всередину колії найбільш імовірне в порожніх вагонах у кривих та навіть прямих ділянках колії, коли вагон витискається під час гальмування поїзда вгору й одночасно встановлюється в «ялинку» під дією набігаючих незагальмованих вагонів. Поперечна сила, яка при цьому виникає, притискає гребінь колеса до зношеної бокової грані головки рейки, а за наявності навіть незначного повороту рейки гребінь колеса по похилій площині бокової грані вкочується спочатку на головку рейки, а через кілька метрів зістрибує з рейки на шпали і далі на баластну призму [10,13,23].…”
Purpose. The work is aimed at determining the influence of the lateral displacement of a freight car bogie, taking into account the value of the movement speed on its main dynamic indicators and interaction indicators of the rolling stock and the track. Methodology. The quantitative assessment of dynamic indicators was obtained by the method of mathematical and computer modeling. The design scheme of the car takes into account the interaction peculiarities of cars as part of the train: the possibility of all modes of body vibration in space, the transmission of longitudinal force from neighboring cars in vertical and horizontal directions, taking into account the technical condition of individual parts of the car and their design features, as well as various operating conditions. Findings. During the research, a mathematical model of a coupling of five freight cars was applied to study the dynamic loading of a gondola car and a track. Main dynamic and interaction indicators of the rolling stock and the track in case of transverse bogie displacement when moving along curved track sections assessment were assessed. The maximum possible values of the lateral displacement of the freight car bogie were substantiated. Originality. The mathematical model of the coupling of freight cars in the train has been improved. In the calculation schemes describing the vibrations of the cars, the peculiarities of the freight car bogies, lozenging of the bogie side frames are taken into account. The model makes it possible to study the effect of changing rotation angle of the central axis of the car body, which in turn leads to the lateral displacement of bogies relative to each other, on the main dynamic and interaction indicators of the rolling stock and the track. For the first time, the influence of transverse displacement of the bogie was investigated, taking into account the wear of its parts and assemblies when moving on track sections with unevenness. Practical value. The calculation results can be used to assess the influence of the bogie transverse displacement on the dynamic qualities of the rolling stock and interaction indicators of the rolling stock and the track, taking into account the wear of parts and units of the bogie when moving in straight and curved track sections with irregularities. The application of the results obtained will contribute to an increase in the stability of freight rolling stock in the conditions of increasing travel speeds, which in turn will allow developing technical conditions for the implementation of resource-saving technologies for transporting goods that meet the safety requirements of train traffic.
“…The mesh size of flange is 1.5 mm and that of the tread is 7 mm. 27,28 The vehicle’s FE model is shown in Figure 1. Figure 1.FE model of a subway head vehicle.…”
Section: Fe Model For the Vehicle’s Oblique Collisionmentioning
Oblique collisions can more easily lead to train derailment and cause heavy casualties. In this paper, a fine finite-element model of a subway head vehicle–rigid wall frontal oblique collision was established and validated by a single wheelset derailment simulation. Furthermore, the derailment mechanisms and patterns under an oblique impact angle of 6.34°–40° and at an impact speed of 8–40 km/h were studied via simulation. The results indicated that three types of derailment, such as roll-over derailment, climb/roll-over derailment and wheel-lift derailment, have occurred. When the impact speed was set to 25 km/h, a climb/roll-over derailment occurred under the impact angle of greater than 40°; a roll-over derailment occurred under the impact angle of 20°–40°; and the vehicle would not derail when the impact angle was less than 15°. When the impact angle was 6.34°, the vehicle was in danger of wheel-lift derailment with the largest wheel vertical displacement of 26.83 mm and lateral displacement of 12.52 mm under the impact speed of 40 km/h, but it was safe with the largest displacement of no more than 18 mm and lateral displacement of 8.39 mm if the impact speed was less than 40 km/h. It is shown that the derailment patterns are more sensitive to the impact angle. Therefore, both the lateral and vertical displacements should be considered when studying the oblique collision-induced derailment mechanisms and patterns.
“…The simulation of the longitudinal train dynamics (LTD) thus plays a crucial role for the prediction of the speed and position of each vehicle in the train composition during a specific trip on a selected route and especially of the in-train forces acting on each coupling system [4]. In fact, high tensile forces can lead to damages of the coupling systems and even to breaking of the train composition, while large compressive forces can cause train derailments [5], [6].…”
Large speeds and axle-loads are required for modern freight trains, which can cause a big rise in in-train forces on wagon coupling elements for both tensile and compressive states, thus possibly leading to breaking of the coupling systems and to train derailments, respectively. Therefore, longitudinal train dynamics (LTD) simulations are a key tool for the prediction of the in-train forces and for the design of coupling and braking systems as well as for the optimization of the train composition. LTD simulations are typically carried out in time domain, to account for all the system non-linearities, mainly the hysteretic behaviour of the coupling system mechanical impedance characteristic. Although time domain simulations are a powerful tool to predict in-train forces considering all the system non-linearities, also frequency domain analyses can be useful to quickly compute the system dynamic behaviour. More in detail, modal analysis can provide important information on the system natural frequencies, so that the frequency content of the input forces can be checked to avoid the excitation of the system natural vibration modes.The paper shows the development of a new efficient time domain simulation LTD code implemented in MATLAb, provided with a modal analysis post-processing routine. The code was validated on the four time domain simulation scenarios suggested by the international benchmark of LTD simulators, and a simplified modal analysis was also carried out on the same train configurations. The validation process highlighted that the new code provides stable numerical outputs with a good computational efficiency, while the modal analysis routine showed that the train eigenfrequencies can vary significantly according to the deflection, relative speed and loading state on each coupler.
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