Numerical Study on the Evolution of Force Chain inside Railway Ballast under Tamping Operation

2015 ◽  
Vol 724 ◽  
pp. 275-278
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Ping Xu ◽  
Bo Yan
Keyword(s):  
Discrete Element Method ◽  
Mechanical Behavior ◽  
Numerical Simulations ◽  
Carrying Capacity ◽  
Numerical Study ◽  
Three Dimensional ◽  
Railway Track ◽  
Force Chains ◽  
Analysis Model ◽  
Railway Ballast

The tamping maintenance of railway ballast is employed to restore the geometry of railway track distorted by train traffics. In this paper, based on the analysis of tamping principle, the three dimensional analysis model of railway ballast is created using the discrete element method, numerical simulations are performed to study the micro mechanical behavior of railway ballast under tamping operation. This paper presents the evolution of force chains inside railway ballast under tamping operation. The obtained results are showed that the contact force inside railway ballast is enhanced by tamping, so as to improve the carrying capacity and stability of railway track.

Experimental and Numerical Study of Railway Ballast Compactness during Tamping Process

2013 ◽  
Vol 690-693 ◽  
pp. 2730-2733
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bo Yan ◽  
Jun Feng Sun
Keyword(s):  
Discrete Element Method ◽  
Numerical Study ◽  
Discrete Element ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Before And After ◽  
Filling Method ◽  
Element Method

Railway ballast tamping operations is employed in order to restore the geometry of railway track distorted by train traffics. The main goal is to compact the stone ballast under the sleepers supporting the railway squeezing and vibrations. The ballast compactness is the most direct index for evaluating the effect of tamping operation. This paper presents an experimental method used to detect the railway ballast compactness before and after tamping operation based on water-filling method, and creates a discrete element analysis model of railway ballast which analyzes the change of ballast compactness before and after tamping operation based on discrete element method. The simulation results are very similar with experimental results, which verify that the discrete element method is an effective method to evaluate the change of railway ballast compactness during tamping process.

scholarly journals Discrete Element Method Simulation of Railway Ballast Compactness During Tamping Process

2013 ◽  
Vol 7 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Taoyong Zhou ◽  
Bin Hu ◽  
Junfeng Sun ◽  
Zhongtian Liu
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Simulation Data ◽  
Element Analysis ◽  
Discrete Element Method Simulation ◽  
Change Trend ◽  
Element Method

Railway ballast tamping operation is employed in order to restore the geometry of railway track distorted by train traffics. In this paper, based on analysis of tamping principle, the discrete element analysis model of railway ballast is created using the discrete element method, numerical simulations are performed to study the change of railway ballast compactness during tamping process. This paper presents the motion trend of stone ballasts as the change trend of railway ballast compactness in qualitative analysis, and the distance between stone ballast and sleeper as the change index of railway ballast compactness in quantitative analysis. By comparing simulation data of different vibration frequencies, an optimal vibration frequency is obtained. The simulation results accord with the actual industrial tamping operation, which verifies that the discrete element method is an effective method to evaluate the change of railway ballast compactness during tamping process.

Numerical Study Porosity of Railway Ballast during Tamping Process

2014 ◽  
Vol 919-921 ◽  
pp. 1124-1127
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Xue Yu Zhao ◽  
Bo Yan
Keyword(s):  
Discrete Element Method ◽  
Vibration Frequency ◽  
Numerical Study ◽  
Discrete Element ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Maintenance Work ◽  
Railway Maintenance ◽  
Element Method

Tamping operation is an important part of railway maintenance work. The porosity of railway ballast is an important maintenance quality evaluation index during tamping process. In this paper, based on the discrete characteristics of railway ballast, the discrete element analysis model of railway ballast is created using the discrete element method, numerical simulations are performed to study the evolution of porosity of railway ballast under sleeper during tamping process. This paper focuses on the influence of vibration frequency of tamping tines during tamping process; an optimal vibration frequency is obtained from the simulation and compared with the actual vibration frequency recommended by China Railway Large Maintenance Machinery Co., Ltd. Kunming, it is found that the two vibration frequency is consistent. This result verifies that the discrete element method is an effective method to study the evolution of porosity of railway ballast during tamping process.

Discrete Element Method Simulation of Mesomechanics of Railway Ballast during Tamping Process

2013 ◽  
Vol 690-693 ◽  
pp. 2726-2729 ◽  
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bo Yan ◽  
Ping Xu
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Interaction Force ◽  
Practical Experience ◽  
Field Trials ◽  
Railway Track ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Element Method

Railway ballast tamping operations is employed in order to restore the geometry of railway track distorted by train traffics. The selection of tamping parameter is usually dependent on field trials and practical experience, for lack of theoretical basis. This paper creates discrete element analysis model of railway ballast using the discrete element method, the numerical simulations are carried out to study the mesomechanics of railway ballast during tamping process. We focus on the change of railway ballast compactness and stone ballast interaction force during tamping process. The present study can be helpful for the analysis of the internal mechanism of ballast compaction during tamping process.

scholarly journals A Numerical Study of Railway Ballast Subjected to Direct Shearing Using the Discrete Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Hongyi Zhao ◽  
Jing Chen
Keyword(s):  
Discrete Element Method ◽  
Mechanical Performance ◽  
Numerical Study ◽  
Discrete Element ◽  
Contact Forces ◽  
Angle Of Repose ◽  
Particle Rotation ◽  
Railway Ballast ◽  
Depth Analysis ◽  
Element Method

Railway ballast is a coarse granular material used to carry train loads and provide drainage for the rail tracks. This study presents numerical explorations of the mechanical performance of ballast aggregates subjected to direct shear tests. The discrete element method (DEM) was used to investigate the microscopic characteristics of ballast aggregates during shearing while considering contact distribution, particle rotation, and particle displacement. By testing the angle of repose of ballast aggregates, the parameters for the DEM contact model could be calibrated. Four specimens were prepared and then subjected to different normal pressures. The results show that the contact between ballast particles intensifies in terms of the amount and magnitude as the normal pressure increases. A Fourier analysis was applied to investigate the anisotropy of contact normal and the contact forces for ballast aggregates at different shearing phases. The rotational and translational movements of ballast particles were investigated, and this investigation revealed that particle rotation gradually increased as the shearing propagated. Four regions in the aggregates were identified according to the translational pattern of ballast particles. The results of this research provide an in-depth analysis of microscopic characteristics from a particulate scale.

Discrete Element Method Analysis of Mechanical Properties of Railway Ballast during Tamping Process under Different Amplitude

2012 ◽  
Vol 233 ◽  
pp. 224-227 ◽  
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Xue Jun Wang ◽  
Bo Yan
Keyword(s):  
Mechanical Properties ◽  
Discrete Element Method ◽  
Simulation Analysis ◽  
Discrete Element ◽  
Practical Experience ◽  
Field Trials ◽  
Analysis Model ◽  
Railway Ballast ◽  
Element Analysis ◽  
Element Method

Railway ballast tamping operations is an important work in the line maintenance and repair operations, the selection of tamping parameter is usually dependent on field trials and practical experience, for the mechanical properties of railway ballast is difficult to measure and describe. This paper creates discrete element analysis model of railway ballast using the discrete element method, the numerical simulations are carried out to study the mechanical properties of railway ballast during tamping process. We focus on the influence of amplitude during tamping process; an optimal amplitude of the simulation analysis is obtained and compared with the recommended amplitude of Plasser & Theurer Company, it is found that the two amplitudes accord. This result verifies the correct validity of the discrete element analysis model of railway ballast during tamping process.

scholarly journals Numerical study of jets produced by conical wire arrays on the Magpie pulsed power generator

2010 ◽  
Vol 6 (S274) ◽  
pp. 429-432
Author(s):  
Matteo Bocchi ◽  
Jerry P. Chittenden ◽  
Andrea Ciardi ◽  
Francisco Suzuki-Vidal ◽  
Gareth N. Hall ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Pulsed Power ◽  
Astrophysical Jets ◽  
Power Generator ◽  
Wire Arrays ◽  
Pulsed Power Generator

AbstractWith the aim to model jets produced by conical wire arrays on the MAGPIE generator, and to strengthen the link between laboratory and astrophysical jets, we performed three-dimensional magneto-hydro-dynamic numerical simulations using the code GORGON and successfully reproduced the experiments. We found that a minimum resolution of ~100 μm is required to retrieve the unstable character of the jet. Moreover, arrays with less wires produce more unstable jets with stronger magnetic fields around them.

scholarly journals Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

2014 ◽  
Vol 6 ◽  
pp. 565061 ◽  
Author(s):  
Zhi-Jun Shuai ◽  
Wan-You Li ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Dominant Frequency ◽  
Water Pump ◽  
Flow Induced Vibration ◽  
Impeller Blade

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

Study Behavior of Railway Ballast under Cyclic Loading

2014 ◽  
Vol 919-921 ◽  
pp. 1155-1159
Author(s):  
Tao Yong Zhou ◽  
Bin Hu ◽  
Bin Hua
Keyword(s):  
Numerical Simulation ◽  
Cyclic Loading ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Railway Track ◽  
Experimental Facility ◽  
Railway Ballast ◽  
Study Behavior ◽  
Rate Of Increase ◽  
Simulation Results

Densification and settlement are two important behavior parameters of railway ballast under cyclic loading. This paper presents numerical simulation using discrete element method which studies the evolution of densification of railway ballast in specified region under cyclic loading. The simulation results show that with the increase of cyclic loading time, the densification of railway ballast under sleeper is also increasing, and the rate of increase becomes smaller and smaller. This paper presents a new full-scale complete railway track loading experimental facility which studies the evolution of settlement of ballasted railway track under cyclic loading. The experimental results show that with the increase of number of load cycles, the settlement of ballasted railway track is also increasing, and the rate of increase becomes smaller and smaller.

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