Thermal deformation and interfacial separation of a CRTS II slab ballastless track multilayer structure used in high-speed railways based on meteorological data

Abstract. High-speed railways are fast-growing and promising type of traffic. In Russia development of high-speed railway service is associated with the solution of a number of problems, including infrastructure. Authors propose to use earth connection of the railway catenary with the help of an artificial earthing switch on currently designed high-speed line Moscow—Kazan for 2×25 kV power supply system. Taking into account requirements for electrical safety conditions for maintenance of the track and earthed catenary supports, paper justifies method for calculating allowable voltages of rail—earth points and supports of catenary. Methods takes into account structural features of ballastless track superstructure used for high-speed lines. It is estimated that the voltages admissible under the electrical safety conditions are random in nature and distributed logarithmically normal. When calculating probability of safe operation, one should take into account random nature of both permissible stresses and those actually occurring on the track. It is estimated that the probability of safe operation in traction networks of sections with ballastless track superstructure does not exceed a similar value in electrified sections with the conventional structure of a ballast prism. Feasibility of using a 2×25 kV earth system using an artificial earth connection is confirmed, recommendations on its use are given. Authors substantiate allowable values of the rail—earth voltage and catenary supports, which practically exclude the occurrence of hazardous situations for personnel maintaining the track in sections with ballastless track superstructure.

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Mechanical Performance of a Ballastless Track System for the Railway Bridges of High-Speed Lines: Experimental and Numerical Study under Thermal Loading

Materials ◽

10.3390/ma14112876 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2876

Author(s):

Yingying Zhang ◽

Lingyu Zhou ◽

Akim D. Mahunon ◽

Guangchao Zhang ◽

Xiusheng Peng ◽

...

Keyword(s):

High Speed ◽

Thermal Loading ◽

Mechanical Performance ◽

Track Structure ◽

Box Girder ◽

High Speed Railway ◽

Ballastless Track ◽

Track System ◽

Girder Bridge ◽

Track Slab

The mechanical performance of China Railway Track System type II (CRTS II) ballastless track suitable for High-Speed Railway (HSR) bridges is investigated in this project by testing a one-quarter-scaled three-span specimen under thermal loading. Stress analysis was performed both experimentally and numerically, via finite-element modeling in the latter case. The results showed that strains in the track slab, in the cement-emulsified asphalt (CA) mortar and in the track bed, increased nonlinearly with the temperature increase. In the longitudinal direction, the zero-displacement section between the track slab and the track bed was close to the 1/8L section of the beam, while the zero-displacement section between the track slab and the box girder bridge was close to the 3/8L section. The maximum values of the relative vertical displacement between the track bed and the bridge structure occurred in the section at three-quarters of the span. Numerical analysis showed that the lower the temperature, the larger the tensile stresses occurring in the different layers of the track structure, whereas the higher the temperature, the higher the relative displacement between the track system and the box girder bridge. Consequently, quantifying the stresses in the various components of the track structure resulting from sudden temperature drops and evaluating the relative displacements between the rails and the track bed resulting from high-temperature are helpful in the design of ballastless track structures for high-speed railway lines.

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Design and thermal characteristic analysis of motorized spindle cooling system

Advances in Mechanical Engineering ◽

10.1177/16878140211020878 ◽

2021 ◽

Vol 13 (5) ◽

pp. 168781402110208

Author(s):

Yuan Zhang ◽

Lifeng Wang ◽

Yaodong Zhang ◽

Yongde Zhang

Keyword(s):

Flow Rate ◽

High Speed ◽

Thermal Deformation ◽

Cooling System ◽

Thermal Characteristic ◽

Water Flow Rate ◽

Thermal Characteristics ◽

Characteristic Analysis ◽

Motorized Spindle ◽

Experiment And Simulation

The thermal deformation of high-speed motorized spindle will affect its reliability, so fully considering its thermal characteristics is the premise of optimal design. In order to study the thermal characteristics of high-speed motorized spindles, a coupled model of thermal-flow-structure was established. Through experiment and simulation, the thermal characteristics of spiral cooling motorized spindle are studied, and the U-shaped cooled motorized spindle is designed and optimized. The simulation results show that when the diameter of the cooling channel is 7 mm, the temperature of the spiral cooling system is lower than that of the U-shaped cooling system, but the radial thermal deformation is greater than that of the U-shaped cooling system. As the increase of the channel diameter of U-shaped cooling system, the temperature and radial thermal deformation decrease. When the diameter is 10 mm, the temperature and radial thermal deformation are lower than the spiral cooling system. And as the flow rate increases, the temperature and radial thermal deformation gradually decrease, which provides a basis for a reasonable choice of water flow rate. The maximum error between experiment and simulation is 2°C, and the error is small, which verifies the accuracy and lays the foundation for future research.

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The Calculation of the Supporting Stress of Track Plate in Ballastless High-Speed Rail Structure

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.97-98.3 ◽

2011 ◽

Vol 97-98 ◽

pp. 3-9

Author(s):

Yang Wang ◽

Quan Mei Gong ◽

Mei Fang Li

Keyword(s):

Stress Distribution ◽

High Speed ◽

Design Theory ◽

Moving Load ◽

Structure Design ◽

Track Structure ◽

Beam Model ◽

High Speed Rail ◽

Slab Track ◽

Ballastless Track

The slab track is a new sort of track structure, which has been widely used in high-speed rail and special line for passenger. However, the ballastless track structure design theory is still not perfect and can not meet the requirements of current high-speed rail and passenger line ballastless track. In this paper, composite beam method is used to calculate the deflection of the track plate and in this way the vertical supporting stress distribution of the track plate can be gotten which set a basis for the follow-up study of the dynamic stress distribution in the subgrade. Slab track plate’s bearing stress under moving load is analyzed through Matlab program. By calculation and analysis, it is found that the deflection of track plate and the rail in the double-point-supported finite beam model refers to the rate of spring coefficient of the fastener and the mortar.The supporting stress of the rail plate is inversely proportional to the supporting stress of the rail. The two boundary conditions of that model ,namely, setting the end of the model in the seams of the track plate or not , have little effect on the results. We can use the supporting stress of the track plates on state 1to get the distribution of the supporting stress in the track plate when bogies pass. Also, when the dynamic load magnification factor is 1.2, the track plate supporting stress of CRST I & CRST II-plate non-ballasted structure is around 40kPa.

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Measurement and Analysis on Transient Thermal Characteristics of High Speed Motorized Spindle

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.52-54.2021 ◽

2011 ◽

Vol 52-54 ◽

pp. 2021-2026

Author(s):

Gui Ling Deng ◽

Can Zhou

Keyword(s):

High Speed ◽

Thermal Deformation ◽

Thermal Characteristics ◽

Measuring System ◽

Test Results ◽

Motorized Spindle ◽

Measurement And Analysis ◽

Turning Center ◽

Transient Thermal ◽

Deformation Compensation

Thermal deformation is an important factor to affect the accuracy of the motorized spindle, the core component of high-speed machine tool. To understand the spindle system transient thermal characteristics of the high-speed turning center CH7516GS, some high-precision sensors and high-frequency data acquisition system is used to establish the temperature and displacement measuring system. The thermal deformation compensation model is established on the basis of the experimental test results.

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Random-Forest Machine Learning Approach for High-Speed Railway Track Slab Deformation Identification Using Track-Side Vibration Monitoring

Applied Sciences ◽

10.3390/app11114756 ◽

2021 ◽

Vol 11 (11) ◽

pp. 4756

Author(s):

Gaoran Guo ◽

Xuhao Cui ◽

Bowen Du

Keyword(s):

Random Forest ◽

High Speed ◽

Recognition Rate ◽

Operation Time ◽

Deformation Monitoring ◽

Vibration Monitoring ◽

Railway Track ◽

Ballastless Track ◽

Train Operation ◽

Track Slab

High-speed railways (HSRs) are established all over the world owing to their advantages of high speed, ride comfort, and low vibration and noise. A ballastless track slab is a crucial part of the HSR, and its working condition directly affects the safe operation of the train. With increasing train operation time, track slabs suffer from various defects such as track slab warping and arching as well as interlayer disengagement defect. These defects will eventually lead to the deformation of track slabs and thus jeopardize safe train operation. Therefore, it is important to monitor the condition of ballastless track slabs and identify their defects. This paper proposes a method for monitoring track slab deformation using fiber optic sensing technology and an intelligent method for identifying track slab deformation using the random-forest model. The results show that track-side monitoring can effectively capture the vibration signals caused by train vibration, track slab deformation, noise, and environmental vibration. The proposed intelligent algorithm can identify track slab deformation effectively, and the recognition rate can reach 96.09%. This paper provides new methods for track slab deformation monitoring and intelligent identification.

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