A study of the effect of the transition curve in the coupling elements between the carbody and the bogie (original) (raw)
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The dynamic behaviour of the railway vehicles dependents on the interaction that is developed between the wheels of the rolling stock and the rails. Furthermore, one of the most sensible issues in the railway industry is the damage on vehicles caused by the track conditions and the infrastructure deterioration due to the trainsets' operation. The study of such phenomena requires the accurate definition of the track geometry that involves, not only the representation of the design track layout, but also the description of its irregularities. In this work, a methodology that includes the track imperfections, measured experimentally by the railroad companies, in the definition of the track model is developed. The purpose is to obtain realistic representations of the track, which are essential to study the dynamics of railway vehicles. The methodology described in this work is applied to study the influence of the track irregularities on the dynamic behaviour of the railway vehicle ML95, which is operated by the Lisbon metro company. For this purpose, a multibody formulation is used to build the vehicle model and a generic wheel-rail contact formulation is applied in order to determine, online during the dynamic analysis, the contact points location and the re-J. Pombo ( ) · J. Ambrósio spective normal and tangential forces. The studies are performed in real operation conditions when travelling between two of the metro stations. The accuracy and suitability of the methodology presented here is demonstrated through the comparison of the dynamic analysis results against those obtained by experimental testing.
A 3D model for coupling dynamics analysis of high-speed train/track system
Journal of Zhejiang University Science A
A three-dimensional dynamic model of a high-speed train coupled with a flexible ballast track was developed and is presented in this paper. In the model, each vehicle was modeled as a 42 degrees of freedom multi-body system, which takes into consideration the nonlinear dynamic characteristics of the suspensions. A detailed inter-vehicle connection model including nonlinear couplers and inter-vehicle dampers, and the linear tight-lock vestibule diaphragm is established to simulate the effect of the end connections of neighboring vehicles on dynamic behavior. The track is modeled as a traditional 3-layer discrete elastic support model. The rails are assumed to be Timoshenko beams supported by discrete sleepers. Each sleeper is treated as an Euler beam and the ballast bed is replaced by equivalent rigid ballast bodies. The reliability of the present model was then validated through a detailed numerical simulation comparison with the commercial software SIMPACK, with the effect of the track flexibility on the train/track interaction being analyzed simultaneously. The proposed model was finally applied to investigate the difference between dynamic performances obtained by using the entire-train/track model (TTM) and the single-vehicle/track model (VTM). Several key dynamic performances, including vibration frequency response, ride comfort, curving performance, calculated by the two types of dynamic models are compared and discussed in detail. The numerical results show that there is a significant difference between the dynamic behaviors obtained by VTM and TTM, and that inter-vehicle connections have an important influence on the dynamic behavior of high-speed vehicles.
Journal of Theoretical and Applied Mechanics, 2016
Dynamic behavior of a track-train system is a function of axle loads and support stiffness because of non-linear supports. Therefore, it is expected that the support stiffness affects the behavior of the railway track during passing of a light or heavy car body. Since the effects of axle loads caused by light and heavy railway vehicles and support stiffness of ballasted railway tracks due to passing railway vehicles have not been studied adequately, therefore the present study focused on this issue. For this purpose, this issue was first investigated by passing a light and heavy car body including bogies with three axle loads as field tests. Then, numerical analyses of the railway track caused by the passing of these railway vehicles were studied, and the numerical results were compared with the field results. There was a good agreement between the values of field responses and numerical analyses. Subsequently, a series of sensitivity analyses on effects of the axle loads caused by light or heavy loading and support conditions was done on the ballasted railway track. The results indicated that the maximum vertical displacements increased by axle loads, increased sleeper distances and decreases support stiffness. Finally, equations of track behavior based on support stiffness and axle loads were derived.
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This paper presents an insight into mathematical analysis of dynamic models of the vehicle-track system. After identification of its advantages and disadvantages, an improved three-dimensional "vehicle-track" system of a mathematical model is presented. It not only assesses the influence of realistic track irregularities but also on all elements of the railway structure: rail, rail pads, sleepers, ballasts, and subballast parameters on the wagon's movement smoothness. Based on the expanded mathematical model of the "vehicle-track" dynamic system, the dynamic process of the wagon was theoretically studied, and the effect of track with irregularities on the vibrations of the wagon elements was studied. The final conclusions and recommendations are presented.