Semianalytical Solution for Dynamic Responses of Railway Track System on Unsaturated Poroelastic Half-Space Subjected to Moving Trainload

2021 ◽  
Vol 21 (3) ◽  
pp. 04021016
Author(s):  
Chuxuan Tang ◽  
Zheng Lu ◽  
Hailin Yao ◽  
Shuan Guo ◽  
Xiangqun Huang ◽  
...  
Keyword(s):  
Half Space ◽  
Dynamic Responses ◽  
Railway Track ◽  
Track System

IMPORTANCE OF NONLINEARITY OF TRACK SUPPORT SYSTEM IN MODELING OF RAILWAY TRACK DYNAMICS

2013 ◽  
Vol 13 (01) ◽  
pp. 1350008 ◽  
Author(s):  
J. SADEGHI ◽  
M. FESHARAKI
Keyword(s):  
Support System ◽  
Field Tests ◽  
Field Investigation ◽  
Dynamic Responses ◽  
Railway Track ◽  
Nonlinear Properties ◽  
Railway Tracks ◽  
Track Dynamics ◽  
Track System ◽  
Axle Loads

Attention is drawn to the fact that the recent increase in axle loads, speed and traffic volume in railway tracks, as well as concerns over passengers' riding comfort and safety have resulted in fresh challenges that are needed to be addressed. These challenges can only be successfully tackled with a more accurate modeling of the dynamic behavior of railway tracks. Although a significant amount of research involving mathematical modeling of railway track dynamics has been conducted in the last two decades, the nonlinearity of track support systems has not been given sufficient attention. This paper is concerned with the effect of nonlinearity of the support sub-layers on the dynamic responses of the railway track. To this end, a railway track model that considers the nonlinear properties of the track sub-layers is developed. Then, a field investigation into the dynamic responses of the railway track system under moving trains is conducted. The effect of the nonlinearity properties of the track support system on the track responses is investigated by comparing the results obtained by the numerical model, with or without consideration of track support nonlinearity, with those from the field tests. It is illustrated that consideration of the nonlinear properties of the track support system improves the accuracy of the calculated responses by a factor of three. It is also shown that the train axle loads and track accumulative loading have a significant effect on the nonlinearity of the track support system and, as a result, on the modeling of track responses.

Dynamic Simulation of Ballastless Railway Track System with Local Invalid Sleepers

2013 ◽  
Vol 423-426 ◽  
pp. 1217-1220
Author(s):  
Huai Liang Zhu ◽  
Ying Dong Fang ◽  
Li Feng Yu
Keyword(s):  
Finite Element ◽  
System Change ◽  
Dynamic Responses ◽  
Railway Track ◽  
Viscoelastic Foundation ◽  
Moving Loads ◽  
Bernoulli Beam ◽  
Maximum Value ◽  
Track System ◽  
Euler Bernoulli Beam

Considering local sleepers supported invalidly, the dynamic analysis is presented for ballastless railway track system subjected to moving loads. The track is modeled as an infinitely Euler-Bernoulli beam with Kelvin viscoelastic foundation. The restrain conditions of system change suddenly at unsupported sleepers. Numerical simulating was carried out by the finite element discrete and Newmarks-method. Dynamic responses of system were analyzed in the case of single or multi-sleeper to be not working properly. Results show that the maximum value of displacement of track is going up 50% approximately due to an invalid sleeper occurring. The amplitude of vibration is two times increase when three sleepers to be hung up. Hence, there would be a bad effect on the vibration control of ballastless railway track system as some sleepers lose efficacy continuously.

Vibration Analysis of Railway Tracks Considering Weld Surface Irregularities

2016 ◽  
Vol 16 (06) ◽  
pp. 1550024 ◽  
Author(s):  
Meysam Naeimi ◽  
Morad Shadfar ◽  
Mohammad Mehrali
Keyword(s):  
Vibration Analysis ◽  
Coupled Model ◽  
Dynamic Responses ◽  
Railway Track ◽  
Dynamic Simulations ◽  
Track System ◽  
Dynamic Forces ◽  
Dynamic Amplification ◽  
The Time Domain ◽  
The Individual

Employing a coupled model for vehicle–track interaction, this paper presented the dynamic analysis of railway track system in the presence of weld irregularities with different geometric profiles in two parallel rails. A 3D model of a standard railway wagon running on a ballasted track system is used to examine the vibrations of the system under track irregularities. Four samples of measured rail profiles at rail welds are considered as the source of dynamic excitations, in which the profiles of parallel rails are unequal. Hence, the individual profiles of left/right rails are imported into the numerical model, taking into account the nonuniform conditions of rail welds in both sides of the railway track. The dynamic responses of the track system caused by irregularities at welds are studied by performing the time-domain vibration analysis. The time histories of the nodal responses under various weld scenarios (measured in an actual railway track site) are recorded. Finally, the peak responses of dynamic forces along the track are determined for left/right rails. The results of dynamic simulations in various weld scenarios are compared and the values of dynamic amplification factors (DAFs) are evaluated. Such findings provide an estimation for the levels of dynamic forces occurring under impact loading conditions of nonuniform rail welds in left/right rails.

scholarly journals Characterization of Vertical Response of Asphalt Trackbed Concrete in Railway Substructure to External Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Bekhzad Yusupov ◽  
Yanjun Qiu ◽  
Galibjon Sharipov ◽  
Chaoyang Wu
Keyword(s):  
Asphalt Concrete ◽  
Dynamic Responses ◽  
Railway Track ◽  
Track Structure ◽  
Fe Model ◽  
Track System ◽  
Proposed Model ◽  
Ground System ◽  
Dynamic Performances ◽  
Specific Factors

Optimizing the dynamic responses of a slab track system is a key aspect to improve the quality of a railway track structure. In this paper, numerical modelling and simulation of vertical dynamics of the railway track structure engaging the asphalt concrete in substructures were carried out. Thus, a 3D finite element (FE) model was developed. The developed model was validated by comparing its outputs, that is, acceleration with the measured ones from realistic experimental data. The good agreement between the simulated and measured data which resulted from the validation confirmed that the proposed model has a capability of simulating the complex dynamic performances of the train-track-ground system under different loading conditions. Analyses of the determined results from the simulation model performances revealed that three specific factors, which were the speed of the train, the temperature, and thickness of the asphalt concrete trackbed, mainly influenced the dynamic behavior of the railway structure. Thereby, those factors were taken into consideration while evaluating the dynamic responses and designing the asphalt concrete trackbed in railway substructures.

scholarly journals Dynamic Responses of Vehicle-CRTS III Slab Track System and Vehicle Running Safety Subjected to Uniform Seismic Excitation

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ping Lou ◽  
Kailun Gong ◽  
Chen Zhao ◽  
Qingyuan Xu ◽  
Robert K. Luo
Keyword(s):  
Reduction Rate ◽  
Seismic Intensity ◽  
Dynamic Responses ◽  
Seismic Excitation ◽  
Wheel Load ◽  
Running Speed ◽  
Running Safety ◽  
Slab Track ◽  
Track System ◽  
Highly Sensitive

The dynamic model for the vehicle-CRTS III slab track system is established subjected to uniform seismic excitation, and the calculation program with MATLAB is compiled and verified. The influences of track parameters, seismic intensity, and running speed of the vehicle on the dynamic responses of the system and the vehicle running safety are analyzed. The results show that (1) the track parameters have certain influence on the dynamic responses of the system, and the seismic intensity and the running speed of the vehicle have important influence on the vehicle running safety; (2) the derailment coefficient is highly sensitive to seismic intensity, and the wheel load reduction rate is also highly sensitive to the running speed of the vehicle.

Finite Element Analysis of a Fishplate Rail Joint in Extreme Environment Condition

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Sunil Kumar Sharma ◽  
Jaesun Lee
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Extreme Environment ◽  
High Rate ◽  
Railway Track ◽  
Element Analysis ◽  
Track System ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Railways are very efficient mode of transportation. Speed limits of the railways and loads they carry are increasing rapidly. Due to some advantages, the insulated rail joints are still the part of a rail-track system. However, a high rate of failure of joints puts the railway track at risk. Therefore, a detailed study of these joints is required. In this paper, a three-dimensional finite element model of rail-fishplate joint is created using Abaqus - a finite element method-based software. Stresses in fishplate and bolts due to wheel impact are analysed by coupling implicit and explicit methods. It is found that bolts are a critical part of a joint due to stresses and vibrations to which they are subjected. The large number of stresses and vibration can result into loosening of bolts.

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