Track Structure and Microdosimetry of Proton Beams

The increase of axle load and train speed would cause intense wheelrail interactions, and lead to potential vibration related problems in train operation. For the low-frequency vibration reduction of a track system, a multi-layer track structure was proposed and analyzed theoretically and experimentally. Firstly, the analytical solution was derived theoretically, and followed by a parametric analysis to verify the vibration reduction performance. Then, a finite element simulation is carried out to highlight the influence of the tuned slab damper. Finally, the vibration and noise tests are performed to verify the results of the analytical solution and finite element simulation. As the finite element simulation indicates, after installation of the tuned slab damper, the peak reaction force of the foundation can be reduced by 60%, and the peak value of the vertical vibration acceleration would decrease by 50%. The vibration test results show that the insertion losses for the total vibration levels are 13.3 dB in the vertical direction and 21.7 dB in the transverse direction. The noise test results show that the data of each measurement point is smoother and smaller, and the noise in the generating position and propagation path can be reduced by 1.9 dB–5.5 dB.

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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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Influence of ionisation track structure on 20 nm FDSOI transistor

Microelectronics Reliability ◽

10.1016/j.microrel.2021.114179 ◽

2021 ◽

Vol 123 ◽

pp. 114179

Author(s):

Hao Zhang ◽

Hongxia Liu ◽

Ziwen Pan ◽

Shupeng Chen ◽

Ruibo Chen

Keyword(s):

Track Structure ◽

20 Nm

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Deformation Law and Control Limit of CRTSIII Slab Track under Subgrade Frost Heave

Applied Sciences ◽

10.3390/app11083520 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3520

Author(s):

Xiaopei Cai ◽

Qian Zhang ◽

Yanrong Zhang ◽

Qihao Wang ◽

Bicheng Luo ◽

...

Keyword(s):

High Speed ◽

Base Plate ◽

Element Model ◽

Middle Part ◽

Railway Track ◽

Frost Heave ◽

Track Structure ◽

Slab Track ◽

Plastic Damage ◽

Track Irregularity

In order to find out the influence of subgrade frost heave on the deformation of track structure and track irregularity of high-speed railways, a nonlinear damage finite element model for China Railway Track System III (CRTSIII) slab track subgrade was established based on the constitutive theory of concrete plastic damage. The analysis of track structure deformation under different subgrade frost heave conditions was focused on, and amplitude the limit of subgrade frost heave was put forward according to the characteristics of interlayer seams. This work is expected to provide guidance for design and construction. Subgrade frost heave was found to cause cosine-type irregularities of rails and the interlayer seams in the track structure, and the displacement in lower foundation mapping to rail surfaces increased. When frost heave occured in the middle part of the track slab, it caused the greatest amount of track irregularity, resulting in a longer and higher seam. Along with the increase in frost heave amplitude, the length of the seam increased linearly whilst its height increased nonlinearly. When the frost heave amplitude reached 35 mm, cracks appeared along the transverse direction of the upper concrete surface on the base plate due to plastic damage; consequently, the base plate started to bend, which reduced interlayer seams. Based on the critical value of track structures’ interlayer seams under different frost heave conditions, four control limits of subgrade frost heave at different levels of frost heave amplitude/wavelength were obtained.

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