scholarly journals Sudden Variation Effect of Aerodynamic Loads and Safety Analysis of Running Trains When Entering Tunnel Under Crosswind

2020 ◽  
Vol 10 (4) ◽  
pp. 1445 ◽  
Author(s):  
Weichao Yang ◽  
E Deng ◽  
Zhihui Zhu ◽  
Mingfeng Lei ◽  
Chenghua Shi ◽  
...  
Keyword(s):  
High Speed ◽  
Coupling Effect ◽  
Reduction Rate ◽  
Interaction Model ◽  
Train Track ◽  
Wheel Load ◽  
Safety Risk ◽  
Aerodynamic Loads ◽  
Track System ◽  
High Speed Trains

Sudden variation of aerodynamic loads is a potential source of safety accidents of high-speed trains (HSTs). As a follow-up investigation on the aerodynamic response of a HST that enters a tunnel under crosswind environment, this paper focuses on the transient response of a HST’s safety indices based on the train–track coupling interaction model. Firstly, a wind–train–track coupling dynamic model is proposed by introducing transient aerodynamic loads into the vehicle–track system. Secondly, the temporal evolution of safety coefficients indicates that the train’s safety risk increases during tunnel entry with crosswind. Results show that the derailment coefficients and wheel load reduction rate during tunnel entry are not only larger than those in open air, but also those inside the tunnel are due to the sudden disappearance of wind excitation at the tunnel entrance. In addition, the characteristic wind curve, which is the wind velocity against the train speed, is presented for application based on the current specification of the safety criteria threshold. The investigation will be useful in assessing the safety risk of a running train subjected to other aerodynamic attacks, such as the coupling effect of an infrastructure scenario and crosswind in a windy area.

scholarly journals Sudden Variation Effect of Aerodynamic Loads and Safety Analysis of Running Trains when Entering Tunnel under Crosswind

2020 ◽  
Author(s):  
Weichao Yang ◽  
E Deng ◽  
Zhihui Zhu ◽  
Mingfeng Lei ◽  
ChengHua Shi ◽  
...  
Keyword(s):  
High Speed ◽  
Coupling Effect ◽  
Reduction Rate ◽  
Interaction Model ◽  
Wheel Load ◽  
Safety Risk ◽  
Aerodynamic Loads ◽  
Track System ◽  
Train Speed ◽  
Safety Indices

Sudden variation of aerodynamic loads is the potential source of safety accidents of high-speed train (HST). As a follow-up investigation on the aerodynamic response of a HST that enters a tunnel under crosswind environment, this paper focuses on the transient response of a HST’s safety indices based on the train–track coupling interaction model. Firstly, a wind–train–track coupling dynamic model is proposed by introducing transient aerodynamic loads into the vehicle–track system. Secondly, the temporal evolution of safety coefficients indicates that the train’s safety risk increases during tunnel entry with crosswind. Results show that the derailment coefficients and wheel load reduction rate during tunnel entry are not only larger than those in open air but also those inside the tunnel due to the sudden disappearance of wind excitation at the tunnel entrance. In addition, the characteristic wind curve, which is the wind velocity against the train speed, is presented for application based on the current specification of the safety criteria threshold. The investigation will be useful in assessing the safety risk of a running train subjected to other aerodynamic attacks, such as the coupling effect of infrastructure scenario and crosswind in windy area.

scholarly journals Saturated Ground Vibration Analysis Based on a Three-Dimensional Coupled Train-Track-Soil Interaction Model

2019 ◽  
Vol 9 (23) ◽  
pp. 4991 ◽  
Author(s):  
Li ◽  
Su ◽  
Kaewunruen
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Interaction Model ◽  
Ground Vibration ◽  
Field Measurements ◽  
Soil Conditions ◽  
Layered Soils ◽  
Train Track ◽  
Dynamic Interactions ◽  
Vibration Responses

A novel three-dimensional (3D) coupled train-track-soil interaction model is developed based on the multi-body simulation (MBS) principle and finite element modeling (FEM) theory using LS-DYNA. The novel model is capable of determining the highspeed effects of trains on track and foundation. The soils in this model are treated as saturated media. The wheel-rail dynamic interactions under the track irregularity are developed based on the Hertz contact theory. This model was validated by comparing its numerical results with experimental results obtained from field measurements and a good agreement was established. The one-layered saturated soil model is firstly developed to investigate the vibration responses of pore water pressures, effective and total stresses, and displacements of soils under different train speeds and soil moduli. The multi-layered soils with and without piles are then developed to highlight the influences of multi-layered soils and piles on the ground vibration responses. The effects of water on the train-track dynamic interactions are also presented. The original insight from this study provides a new and better understanding into saturated ground vibration responses in high-speed railway systems using slab tracks in practice. This insight will help track engineers to inspect, maintain, and improve soil conditions effectively, resulting in a seamless railway operation.

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.

scholarly journals Polygonisation of railway wheels: a critical review

2020 ◽  
Vol 28 (4) ◽  
pp. 317-345 ◽  
Author(s):  
Gongquan Tao ◽  
Zefeng Wen ◽  
Xuesong Jin ◽  
Xiaoxuan Yang
Keyword(s):  
Critical Review ◽  
High Speed ◽  
Natural Vibration ◽  
Ride Comfort ◽  
Railway Vehicle ◽  
Formation Mechanisms ◽  
Simulation Methods ◽  
Track System ◽  
High Speed Trains ◽  
Railway Wheels

AbstractPolygonisation is a common nonuniform wear phenomenon occurring in railway vehicle wheels and has a severe impact on the vehicle–track system, ride comfort, and lineside residents. This paper first summarizes periodic defects of the wheels, including wheel polygonisation and wheel corrugation, occurring in railways worldwide. Thereafter, the effects of wheel polygonisation on the wheel–rail interaction, noise and vibration, and fatigue failure of the vehicle and track components are reviewed. Based on the different causes, the formation mechanisms of periodic wheel defects are classified into three categories: (1) initial defects of wheels, (2) natural vibration of the vehicle–track system, and (3) thermoelastic instability. In addition, the simulation methods of wheel polygonisation evolution and countermeasures to mitigate wheel polygonisation are presented. Emphasis is given to the characteristics, effects, causes, and solutions of wheel polygonisation in metro vehicles, locomotives, and high-speed trains in China. Finally, the guidance is provided on further understanding the formation mechanisms, monitoring technology, and maintenance criterion of wheel polygonisation.

Dynamic Response of High-Speed Train-Track-Bridge Coupling System Subjected to Simultaneous Wind and Rain

2021 ◽  
pp. 2150161
Author(s):  
Hongye Gou ◽  
Wenhao Li ◽  
Siqing Zhou ◽  
Yi Bao ◽  
Tianqi Zhao ◽  
...  
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Simultaneous Action ◽  
High Speed Train ◽  
Train Track ◽  
Safe Operation ◽  
Coupling System ◽  
High Speed Trains ◽  
Track Bridge ◽  
Bridge System

The Lanzhou-Xinjiang High-speed Railway runs through a region of over 500[Formula: see text]km that is amenable to frequent winds. The strong wind and rainfall pose a great threat to the safe operation of high-speed trains. To tackle the aforementioned climate challenges, this paper investigates the dynamic response of the high-speed train-track-bridge coupling system under the simultaneous action of winds and rains for the safe operation of trains. Specifically, there are four main objectives: (1) to develop a finite element model to analyze the dynamic response of the train-track-bridge system in windy and raining conditions; (2) to investigate the aerodynamic loads posed to the train-track-bridge system by winds and rains; (3) to evaluate the effects of wind speed and rainfall intensity on the train-track-bridge system; and (4) to assess the safety of trains at different train speeds and under various wind-rain conditions. To this end, this paper first establishes a train-track-bridge model via ANSYS and SIMPACK co-simulation and the aerodynamics models of the high-speed train and bridge through FLUENT to form a safety analysis system for high-speed trains running on the bridge under the wind-rain conditions. Then, the response of the train-track-bridge system under different wind speeds and rainfall intensities is studied. The results show that the effects of winds and rains are coupled. The rule of variation for the train dynamic response with respect to various wind and rain conditions is established, with practical suggestions provided for control of the safe operation of high-speed trains.

Condition diagnostics of Russian railways infrastructure constructions under aerodynamic loads from high-speed trains

2014 ◽  
Vol 75 (3) ◽  
pp. 580-586
Author(s):  
S. M. Kaplunov ◽  
N. G. Valles ◽  
V. Yu. Fursov ◽  
A. M. Belostotskii ◽  
S. I. Dubinskii
Keyword(s):  
High Speed ◽  
Aerodynamic Loads ◽  
High Speed Trains

scholarly journals Moving element analysis of high-speed rail system accounting for hanging sleepers

2018 ◽  
Vol 148 ◽  
pp. 05007 ◽  
Author(s):  
Jian Dai ◽  
Kok Keng Ang ◽  
Dongqi Jiang
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
High Speed Train ◽  
Train Track ◽  
Element Analysis ◽  
High Speed Rail ◽  
Factors Affecting ◽  
Rail System ◽  
Track System ◽  
Ballasted Track

It is very common in the ballasted track system that sleepers are not well supported by the ballast materials due to the uneven settlement of the ballast under repeated train passage. These unsupported track elements are often termed as hanging sleepers and they can lead to undesirable effects due to increased dynamic response of the train-track system, especially when the speed of the train is high. In this paper, we present a computation scheme in conjunction with the moving element method for the analysis of high-speed train-track dynamics accounting for hanging sleepers. The proposed computational scheme will be first verified by comparison with available analytical results. The dynamic response of a high-speed train traveling on a ballasted track considering unsupported sleepers is next investigated. Various factors affecting the response of the high-speed rail system including the speed of the train, the number of hanging sleepers and the pattern of the hanging sleepers will be examined and discussed.

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