Dynamic comparison of different types of slab track and ballasted track using a flexible track model

2011 ◽  
Vol 225 (6) ◽  
pp. 574-592 ◽  
Author(s):  
J Blanco-Lorenzo ◽  
J Santamaria ◽  
E G Vadillo ◽  
O Oyarzabal
Keyword(s):  
Dynamic Performance ◽  
Interaction Model ◽  
Fem Analysis ◽  
Wide Frequency Range ◽  
Train Track ◽  
Analysis Software ◽  
Slab Track ◽  
Track System ◽  
Ballasted Track ◽  
Different Types

The dynamic performance of a ballasted track and three types of slab track is analysed and compared by means of a comprehensive dynamic model of the train–track system, generated using two commercial analysis software packages: the commercial multibody system (MBS) analysis software SIMPACK and the finite element method (FEM) analysis software NASTRAN. The use of a commercial MBS software makes it possible to include, in a reliable way, models of advanced non-linear wheel–rail contact as well as complex elements or joints in the vehicle model, while the FEM the flexibility of the rail and the slab to be taken into account. As a result, a combined MBS–FEM representation of the vehicle–track model is integrated into the MBS software, which allows for the study of dynamic phenomena in a wide frequency range. In this study, other simpler approaches for modelling the dynamic vehicle–track interaction are also considered, such as pure multibody or FE representations of the whole vehicle–track system. The quality of the results obtained with the different types of models used is analysed, and some conclusions are put forth regarding the possible validity of rather simple train–track interaction model types under certain conditions as well as the most suitable configuration of the most complex models.

scholarly journals Vertical Dynamic Analysis of Ballastless Tracks on Train-Track- Bridge System

2020 ◽  
Vol 306 ◽  
pp. 02003
Author(s):  
Haoran Xie ◽  
Bin Yan ◽  
Jie Huang
Keyword(s):  
Track Structure ◽  
Vertical Acceleration ◽  
Train Track ◽  
Steel Spring ◽  
Slab Track ◽  
Ballastless Track ◽  
Track System ◽  
Train Speed ◽  
Track Bridge ◽  
Bridge System

In order to investigate the vertical dynamic response characteristics of train-track-bridge system on CWR (Continunously Welded Rail) under dynamic load of train on HSR (High-Speed Railway) bridge. Based on the principle of vehicle train-track-bridge coupling dynamics, taking the 32m simply supported bridge of a section of Zhengzhou-Xuzhou Passenger Dedicated Line as an example, the finite element software ANSYS and the dynamic analysis software SIMPACK are used for co-simulation, and bridge model of the steel spring floating slab track and the CRTSIII ballastless track (China Railway Track System) considering the shock absorbing steel spring, the limit barricade and the contact characteristics of track structure layers are established. On this basis, in order to study the dynamic response laws of the design of ballastless track structure parameters to the system when the train crosses the bridge and provide the basis for the design and construction, by studying the influence of the speed of train on the bridge, the damage of fasteners and the parameters of track structure on the train-track-bridge system, the displacement of rail, vertical vibration acceleration and wheel-rail force response performance are analyzed. Studies have shown that: At the train speed of 40 km/h, the displacement and acceleration of the rail and track slab in the CRTSIII ballastless track are smaller than the floating slab track structure, but the floating slab track structure has better vibration reduction performance for bridges. The acceleration of rail, track slab and bridge increases obviously with the increase of train speed, the rail structure has the largest increasement. Reducing the stiffness of fasteners could decrease the vertical acceleration response of the steel spring floating slab track system, the ability to absorb shock can be enhanceed by reducing the stiffness of the fastener appropriately. Increasing the density of the floating slab can increase the vertical acceleration of the floating slab and the bridge, thereby decreasing the vibration amplitude of the system.

High Speed Rail: Track Construction Considerations

2011 ◽  
Author(s):  
Blaine O. Peterson
Keyword(s):  
High Speed ◽  
Optimal Solution ◽  
Rolling Stock ◽  
High Speed Rail ◽  
Track Geometry ◽  
Slab Track ◽  
Passenger Rail ◽  
Construction Methods ◽  
Track System ◽  
Ballasted Track

This paper discusses general High Speed Rail (HSR) track geometry, construction and maintenance practices and tolerances. The discussion will reference several key international projects and highlight different construction methods and the track geometry assessments used to establish and ensure serviceability of a typical HSR system. Historically, established tighter tolerances of “Express” HSR (i.e. operating speeds greater than 240 km/h or 150 mph) systems have favored the use of slab track systems over ballasted track systems. Slab track systems offer greater inherent stability while ballasted track systems generally require more frequent track geometry assessments and anomaly-correcting surfacing operations. The decisions related to which system to use for a given application involve numerous considerations discussed only briefly in this paper. In many cases, the optimal solution may include both track forms. Rolling stock considerations and their influence on track infrastructure design are considered beyond the scope of this paper. This paper will focus predominantly on two slab track systems widely used in international HSR projects: the Japanese J-slab track system; and the German Rheda slab track system. The French track system will be referenced as the typical ballasted track HSR design. The practices discussed in this paper generally apply to systems which are either primarily or exclusively passenger rail systems. In the U.S., these types of systems will necessarily exclude the systems the Federal Railway Administration (FRA) refers to as “Emerging” or “Regional” HSR systems which include passenger train traffic to share trackage on, what are otherwise considered, primarily freight lines.

scholarly journals Dynamic response of a vehicle with flexible car body moving on a ballasted track

2018 ◽  
Vol 211 ◽  
pp. 11003
Author(s):  
Yingjie Wang ◽  
Zuzana Dimitrovová ◽  
Jong-Dar Yau
Keyword(s):  
Finite Elements ◽  
Dynamic Response ◽  
Integration Method ◽  
Interaction Model ◽  
Flexible Multibody Dynamics ◽  
Flexural Stiffness ◽  
Maximum Acceleration ◽  
Car Body ◽  
Track System ◽  
Ballasted Track

In this study, the dynamic response of a vehicle with flexible car body moving on a ballasted track is investigated. The vehicle/track interaction model is divided into two sub-systems, namely the vehicle and the ballasted track sub-system. The vehicle sub-system is composed by one flexible car body, two bogies and four wheel sets. The car body is created using flexible multibody dynamics. The ballasted track consists of rail, sleeper, ballast and sub-grade. For its representation the simplified 2D discrete support model (DSM) is used and modelled by finite elements. The connection between the two sub-systems, i.e. between the moving wheels and the track is ensured by a linearized Hertzian spring. The dynamic response of the vehicle/track system is computed by the Newmark-β integration method. The effect of the car body flexibility on the dynamic response of this system is analyzed and evaluated based on the maximum car center acceleration. It is concluded that the increase in flexural stiffness of the car body can lead to a notable decrease of its maximum acceleration.

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.

scholarly journals DYNAMIC PERFORMANCE OF LOW VIBRATION SLAB TRACK ON SHARED HIGH-SPEED PASSENGER AND FREIGHT RAILWAY

Transport ◽  
2018 ◽  
Vol 33 (3) ◽  
pp. 669-678
Author(s):  
Qinglie He ◽  
Chengbiao Cai ◽  
Shengyang Zhu ◽  
Jiawei Zhang ◽  
Wanming Zhai
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Vibration Isolation ◽  
Dynamic Models ◽  
Concrete Slab ◽  
Dynamic Performance ◽  
Tension Stress ◽  
Slab Track ◽  
Track System ◽  
Supporting Layer

This work investigates dynamic performance of a low vibration slab track on a shared high-speed passenger and freight railway, and an optimal modulus of the isolation layer (rubber pad) is proposed to meet the adaptability of the track system under the dynamic actions of high speed passenger and heavy axle-load freight trains. First, detailed finite element models of the slab track with and without the rubber pad between concrete slab and supporting layer are established by using software ANSYS. Further, coupled dynamic models of passenger/freight vehicle–low vibration/tradition slab track system are developed to calculate the wheel–rail forces, which are utilized as the inputs to the finite element model. Finally, the dynamic characteristics of the low vibration slab track, the specific function of the rubber pad, and the optimal modulus of the rubber pad are studied in detail. Results show that the interaction force between the freight vehicle and low vibration slab track is more significant because of the heavy axle-load, which leads to larger vertical stress amplitudes of each track layer. Whereas the accelerations of track components induced by the passenger vehicle are much larger than those induced by the freight vehicle, due to the much faster speed that can generate high wheel–rail interaction frequency. The rubber pad of the slab track does not play a role in attenuating slab vibration; instead it causes an increase of slab acceleration and its surface tension stress. However, the rubber pad can decrease the supporting layer acceleration and the slab compression stress, which plays a significant role in vibration isolation and buffers the direct impact force on the slab caused by vehicle dynamic load. To ensure a reasonable vibration level and dynamic stress of the slab track, the optimal modulus of the rubber pad is suggested to be 3÷7.5 MPa.

Dynamic Performance of the LMS Maglev Train–Track–Bridge System Under Uneven Settlement for Two Typical Bridges

2020 ◽  
pp. 2150006
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Ziyan Wu
Keyword(s):  
Numerical Model ◽  
Dynamic Performance ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Dynamic Responses ◽  
Train Track ◽  
Maglev Train ◽  
Medium Speed ◽  
Track Bridge ◽  
Bridge System

To investigate the dynamic performance of the low-to-medium-speed (LMS) maglev train and bridge system under uneven ground settlement, a refined vertical dynamic interaction model of the LMS maglev train–track–bridge system with uneven settlement is proposed. Firstly, the numerical model is verified based on the field test. Secondly, the dynamic performances of the system induced by uneven settlements are numerically analyzed. Furthermore, numerical studies are carried out to investigate the effect of various uneven settlement types, to compare the performances of the two typical bridges, and to assess the contribution of the F-rail in the presence of uneven settlement. The results show that uneven settlement has a significant enlargement effect on the dynamic responses of the car body and levitation module, but a very weak influence on the bridge. Both the patterns of uneven settlement and bridge types significantly affect the dynamic response of the maglev train to various levels. The numerical model excluding the track structure will overestimate the dynamic responses of the levitation module. It is suggested that the dynamic interaction model for the maglev train–track–bridge system be selected to simulate the influence of uneven settlement for better accuracy.

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 THE INFLUENCE OF TRAIN RUNNING DIRECTION AND TRACK SUPPORTS POSITION ON THE BEHAVIOUR OF TRANSITION ZONES

2016 ◽  
Author(s):  
Roberto Sañudo Ortega ◽  
Marina Miranda manzanares ◽  
Valeri Markine ◽  
LUIGI DELL'OLIO
Keyword(s):  
Finite Elements ◽  
Separation Zone ◽  
Maintenance Costs ◽  
Transition Zones ◽  
Slab Track ◽  
Railway Line ◽  
Ballasted Track ◽  
Different Types ◽  
Vertical Displacements ◽  
Separation Zones

Different types of track infrastructure can be found along railway lines. Separation zones between these different types of structures are the source of a lot of problems. Transition zones on a railway line represent a gradual solution for the problems between conventional railway structure and singular structures located at different points along the line. The different nature, positioning and geometry used with the materials generate changes in the stiffness on both sides of these singular zones leading to an increase in wear and a loss of geometry, with the associated maintenance costs. This article describes the use of mathematical modelling to represent the behaviour of these zones as a function of train running direction and track supports. Available research into transition zones has not studied these separation points where high increases in load are generated for very short periods of time. Finite elements are used to model two types of track (conventional ballasted track and slab track), using a vehicle to dynamically simulate the behaviour in these zones as a function of train running direction and the position of track supports. The magnitudes analysed were the vertical stresses and the vertical displacements under the sleepers and the supports in both types of structure. The results show increased stresses at the separation zone between both structures which varied in magnitude and position depending most of track supports’ location than the train running direction.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4073 

scholarly journals Interactions between an Associative Amphiphilic Block Polyelectrolyte and Surfactants in Water: Effect of Charge Type on Solution Properties and Aggregation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1729
Author(s):  
Patrizio Raffa
Keyword(s):  
Surface Tension ◽  
Self Assembly ◽  
Interaction Model ◽  
Industrial Applications ◽  
Molecular Organization ◽  
Different Types ◽  
Solution Rheology ◽  
Interesting Class ◽  
First Time

The study of interactions between polyelectrolytes (PE) and surfactants is of great interest for both fundamental and applied research. These mixtures can represent, for example, models of self-assembly and molecular organization in biological systems, but they are also relevant in industrial applications. Amphiphilic block polyelectrolytes represent an interesting class of PE, but their interactions with surfactants have not been extensively explored so far, most studies being restricted to non-associating PE. In this work, interactions between an anionic amphiphilic triblock polyelectrolyte and different types of surfactants bearing respectively negative, positive and no charge, are investigated via surface tension and solution rheology measurements for the first time. It is evidenced that the surfactants have different effects on viscosity and surface tension, depending on their charge type. Micellization of the surfactant is affected by the presence of the polymer in all cases; shear viscosity of polymer solutions decreases in presence of the same charge or nonionic surfactants, while the opposite charge surfactant causes precipitation. This study highlights the importance of the charge type, and the role of the associating hydrophobic block in the PE structure, on the solution behavior of the mixtures. Moreover, a possible interaction model is proposed, based on the obtained data.

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