The Effect of Thin-layer Elements in Structural Modeling of Rail-track Supporting System PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download The Effect of Thin-layer Elements in Structural Modeling of Rail-track Supporting System PDF full book. Access full book title The Effect of Thin-layer Elements in Structural Modeling of Rail-track Supporting System by Chooi Fong Yeat. Download full books in PDF and EPUB format.
Author: Chooi Fong Yeat
Publisher:
ISBN:
Category : Electric railroads
Languages : en
Pages : 350
Get Book Here
Book Description
A conventional track system consists of rails, sleepers, ballast, sub-ballast, and sub-grade. A track foundation on the basis of live road load response and permanent settlement, it is necessary to use an analytical model that will realisticly represent the actual behaviour of this track system subjected to actual load. This study deals with the development of numerical modeling of Malaysian railway track along with the supporting system. The model is capable to simulate the sleeper, ballast, sub-ballast, soil layers and their interaction as a single compatible unit. Under plane strain condition, the coupled finite-infinite elements were implemented to represent the near field and far field behaviour of media. Thin-layer elements have been used to represent the interfacial behaviour between sleepers and ballast. The following constitutive relationships were adopted in this study: (i)- Linear Elastic (ii)-Elasto-plastic. Based on the above physical material modeling, an existing two dimensional finite element program has been extensively modified in view of including the new elements as well as the new constitutive law. After verification of the modified version of the program, the applicability of the program was shown in analysis of railway track supporting system. The response of the railway track supporting system has been presented under static and dynamic loading. The behaviour of the railway track supporting media has been discussed with the respect to displacement, accelerations and rate of plastic flow. This analysis show that the thin layer element is reliable to be used as an interface element to represent the contact surface between two different materials.
Author: Chooi Fong Yeat
Publisher:
ISBN:
Category : Electric railroads
Languages : en
Pages : 350
Get Book Here
Book Description
A conventional track system consists of rails, sleepers, ballast, sub-ballast, and sub-grade. A track foundation on the basis of live road load response and permanent settlement, it is necessary to use an analytical model that will realisticly represent the actual behaviour of this track system subjected to actual load. This study deals with the development of numerical modeling of Malaysian railway track along with the supporting system. The model is capable to simulate the sleeper, ballast, sub-ballast, soil layers and their interaction as a single compatible unit. Under plane strain condition, the coupled finite-infinite elements were implemented to represent the near field and far field behaviour of media. Thin-layer elements have been used to represent the interfacial behaviour between sleepers and ballast. The following constitutive relationships were adopted in this study: (i)- Linear Elastic (ii)-Elasto-plastic. Based on the above physical material modeling, an existing two dimensional finite element program has been extensively modified in view of including the new elements as well as the new constitutive law. After verification of the modified version of the program, the applicability of the program was shown in analysis of railway track supporting system. The response of the railway track supporting system has been presented under static and dynamic loading. The behaviour of the railway track supporting media has been discussed with the respect to displacement, accelerations and rate of plastic flow. This analysis show that the thin layer element is reliable to be used as an interface element to represent the contact surface between two different materials.
Author:
Publisher: Universities Press
ISBN: 9788173714931
Category : Structural engineering
Languages : en
Pages : 412
Get Book Here
Book Description
This book contains state-of-the-art review articles on specific research areas in the civil engineering discipline-the areas include geotechnical engineering, hydraulics and water resources engineering, and structural engineering. The articles are written by invited authors who are currently active at the international level in their respective research fields.
Author: C.A. Brebbia
Publisher: WIT Press
ISBN: 1784661236
Category : Transportation
Languages : en
Pages : 499
Get Book Here
Book Description
This title incorporates the 15th proceedings of the very successful International Conference on Railway Engineering Design and Operation (COMPRAIL) series, which began in Frankfurt 1987 and continued in Rome (1990); Washington (1992); Madrid (1994); Berlin (1996); Lisbon (1998); Bologna (2000); Lemnos (2002); Dresden (2004); Prague (2006); Toledo (2008); Beijing (2010); the New Forest, home of the Wessex Institute (2012) and, again in Rome in 2014. The papers presented at this conference aim to update the use of advanced systems, promoting their general awareness throughout the management, design, manufacture and operation of railways and other emerging passenger, freight and transit systems. With the conference attracting a variety of specialists, including railway engineers, designers of advanced train control systems and computer specialists, the book particularly emphasises the use of computer systems in advanced railway engineering. Topics include but are not restricted to: Advanced train control Operations quality; Risk management; Planning and policy; Energy supply and consumption; Communications and signalling; Operational planning; Interface management; Systems integration; Maglev; High speed technology; Interoperability; Passenger flow management; Computer simulations and Driverless and automatic train operation.
Author: Simon Iwnicki
Publisher: CRC Press
ISBN: 0429890621
Category : Science
Languages : en
Pages : 972
Get Book Here
Book Description
Handbook of Railway Vehicle Dynamics, Second Edition, provides expanded, fully updated coverage of railway vehicle dynamics. With chapters by international experts, this work surveys the main areas of rolling stock and locomotive dynamics. Through mathematical analysis and numerous practical examples, it builds a deep understanding of the wheel-rail interface, suspension and suspension component design, simulation and testing of electrical and mechanical systems, and interaction with the surrounding infrastructure, and noise and vibration. Topics added in the Second Edition include magnetic levitation, rail vehicle aerodynamics, and advances in traction and braking for full trains and individual vehicles.
Author: Jens C.O. Nielsen
Publisher: Springer
ISBN: 3662448327
Category : Technology & Engineering
Languages : en
Pages : 724
Get Book Here
Book Description
The book reports on the 11th International Workshop on Railway Noise, held on 9 – 13 September, 2013, in Uddevalla, Sweden. The event, which was jointly organized by the Competence Centre Chalmers Railway Mechanics (CHARMEC) and the Departments of Applied Mechanics and Applied Acoustics at Chalmers University of Technology in Gothenburg, Sweden, covered a broad range of topics in the field of railway noise and vibration, including: prospects, legal regulations and perceptions; wheel and rail noise; prediction, measurements and monitoring; ground-borne vibration; squeal noise and structure-borne noise; and aerodynamic noise generated by high-speed trains. Further topics included: resilient track forms; grinding, corrugation and roughness; and interior noise and sound barriers. This book, which consists of a collection of peer-reviewed papers originally submitted to the workshop, not only provides readers with an overview of the latest developments in the field, but also offers scientists and engineers essential support in their daily efforts to identify, understand and solve a number of problems related to railway noise and vibration, and to achieve their ultimate goal of reducing the environmental impact of railway systems.
Author: Yin Gao
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Railroad transportation, especially high-speed passenger rail, has been developing at sensational speed, creating the needs to evaluate the track safety and predict the potential hazards for railroad operation. As train speed increases, the responses of the train and track substructure present larger dynamic behavior, which raises problems in passenger comfort, operational safety and track structures. With the boom of modeling and computing techniques, numerical simulation becomes a more feasible, safe and effective tool to identify the problems in railroad engineering. In this dissertation, a self-developed three-dimensional train-track interaction model is formulated, validated and implemented to predict the potential risks and explore the mechanisms of rail track problems.The developed 3D dynamic track-subgrade interaction model includes a train model, 2D discrete support track model and 3D computation-efficient finite element (FE) soil subgrade model. The rail beam is modeled as a Euler-Bernoulli Beam. The 2D track model discretizes the tie and ballast as rigid bodies with designated spacing. The discretely supported system enables the track model to take the track longitudinal variations into consideration. The subgrade model is simulated by finite element method with quadrilateral elements. Since the subgrade of a tangent track is considered as homogeneous in the moving direction, the formulation of the subgrade is derived in a computing-efficient way by expanding the longitudinal direction in the frequency domain. Therefore, the computing time is significantly reduced. The entire model is a self-developed program, which is coded in MATLAB.Field data collected in x, y, z directions were used to validate the accuracy of the dynamic track-subgrade interaction model. Testing sites were located on Amtraks highest speed (240 km/hr) line near Kingston, Rhode Island, on the Northeast Corridor in United States. Track deflections and the ground wave motion measured in the field were compared with those predicted by the 3D dynamic track-subgrade interaction model.Some applications of the 3D dynamic track-subgrade interaction model are included in this dissertation, as follow.Critical speed study: Amtrak requires more frequent maintenance for the North East Corridor (NEC) at Kingston, Rhode Island (known as the Great Swamp area). It was suspected that a condition, known as critical speed, might exist at this particular location. The conventional definition of critical speed of a railroad system is the speed at which vibrations propagate within the track structure and subgrade at a speed close to the Rayleigh wave velocity of the subgrade soil. As trains travel at speeds approaching the critical speed, all track components are expected to present significantly increased vibrations. However, no historical data indicated such dramatic increment in track responses at the Great Swamp area. Therefore, the 3D dynamic track-subgrade interaction model was used to evaluate the track performance under the current range of operation speeds and predicted the track responses at train speeds higher than the track speed limits. According to the results and analysis, the critical speed effect at the Kingston site could not be comprehensively explained by the conventional definition of the critical speed. Therefore, a two-level explanation is used to address the phenomenon at this site.Hanging tie detection: the hanging tie condition is that in which voids have developed beneath the ties, causing tie-ballast gaps. The existence of the tie-ballast gaps can result in larger peak accelerations at the unsupported or poorly supported ties. This will increase the dynamic contact force between tie and ballast, and then further deteriorate the track structure. However, currently the railroad industry has difficulties in identifying hanging ties in the field since the problem is buried beneath the track. Therefore, the previously developed model was used to propose a fast, nondestructive screening method to identify the hanging tie problem. The method utilized a dynamic track model to characterize the track's Moving Deflection Spectrum (MDS) under different tie-supporting scenarios. The MDSs of tracks without a hanging tie problem have a clear peak at the Tie Spacing Frequency. However, tracks have a hanging tie problem if the MDSs present a significantly increased peak in the low frequency region (the frequency below the Tie Spacing Frequency). The modeling results were further validated by the field investigations conducted on three metro lines in Boston and St. Louis. Accelerometers were mounted on a high-rail vehicle to measure the acceleration of the moving wheels. The MDSs were then calculated to predict the potential locations of hanging ties. The locations of hanging ties predicted by the model matched the field observations. Tie movements characterization: modeling techniques were used to predict the movements of railroad ties under moving train passage in this study. The ballast and other track substructures performances are largely dependent on the tie-ballast contact. Therefore, characterizing the tie movements could potentially bring new concepts to the conventional laboratory tests and practical maintenance for railroad engineering. In order to obtain the tie movements numerically, two steps were made by combining a commercial vehicle dynamics model with a track model established in the commercial software ABAQUS. The modeling results showed that the motion of ties not only contains translational movements, but also rotations. The field tests to validate this finding were conducted on an Amtrak high-speed passenger line and a freight railroad short line. The measuring units were mounted on ties to record the accelerations and the changes in Euler angles of the ties in three orthogonal directions. The measurements of tie displacements and rotations in the field tests had good agreement with the modeling results. Moreover, field tests indicated that the tie-ballast gaps may cause higher accelerations and angular velocities of ties. Then the effect of tie rotation was investigated by discrete element modeling. The modeling results showed that the acceleration of individual ballast particles and ballast contact forces could have significant increase when the tie rotation is considered.Overall, the 3D train-track interaction model is capable of simulating the railroad tracks of various conditions by integrating the discrete supports and 3D subgrade model. The model can be a reliable and effective tool for railroad industry. The versatility of the model makes it have great potential for future research and references.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 52
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 876
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category : Metallurgy
Languages : en
Pages : 1042
Get Book Here
Book Description
Author:
Publisher: Transportation Research Board
ISBN: 0309258243
Category : Technology & Engineering
Languages : en
Pages : 695
Get Book Here
Book Description
TCRP report 155 provides guidelines and descriptions for the design of various common types of light rail transit (LRT) track. The track structure types include ballasted track, direct fixation ("ballastless") track, and embedded track. The report considers the characteristics and interfaces of vehicle wheels and rail, tracks and wheel gauges, rail sections, alignments, speeds, and track moduli. The report includes chapters on vehicles, alignment, track structures, track components, special track work, aerial structures/bridges, corrosion control, noise and vibration, signals, traction power, and the integration of LRT track into urban streets.
