Dynamic characteristic difference of steel-spring floating slab track between single-carriage and multi-carriage models

2021 ◽  
pp. 095745652199986
Author(s):  
Wenhao Chang ◽  
Xiaopei Cai ◽  
Qihao Wang
Keyword(s):  
Coupling Effect ◽  
Three Dimensional ◽  
Coupled Model ◽  
Measured Data ◽  
Dynamic Responses ◽  
Theoretical Research ◽  
Maximum Displacement ◽  
Steel Spring ◽  
Slab Track ◽  
Computation Efficiency

The steel-spring floating slab track (SSFST) is a low-stiffness structure, sensitive to the vehicle loads. Due to the coupling effect of the superposition of adjacent bogies, it is difficult for conventional single-carriage models to meet the simulation requirements. To find a balance between computation efficiency and authenticity of analytical model results, the influence of carriage number on SSFST should be studied. Based on the finite element method and multi-body dynamics, a refined three-dimensional coupled model of multi-carriage-SSFST-tunnel was established. The difference in the dynamic response of the SSFST between single-carriage and multi-carriage models was analyzed and compared with the measured data. The field test results show that structural displacements and accelerations under the two-carriage model are much closer to the measured data. The dynamic model analysis results show that the maximum displacement of the rail and SSFST in the midspan of the slab increase by 0.48 mm and 0.34 mm under the multi-carriage model, and the vibration reduction effectiveness increases by 1.4–2.0 dB. Dynamic responses of the rail and SSFST show minor differences under the two-carriage and three-carriage models. The article is expected to provide a reference for the theoretical research, design, and layout optimization of subway SSFST.

Dynamic Response of the Steel Bridge Deck Thin Surfacing due to Vehicle Load

2010 ◽  
Vol 148-149 ◽  
pp. 544-547
Author(s):  
Xun Qian Xu ◽  
Ye Yuan Ma ◽  
Guo Qing Wu ◽  
Xiu Mei Gao
Keyword(s):  
Dynamic Response ◽  
Bridge Deck ◽  
Three Dimensional ◽  
Coupled Model ◽  
Interface Layer ◽  
Dynamic Responses ◽  
Steel Bridge ◽  
Vehicle Load ◽  
Moving Vehicles ◽  
Space Technique

Basing on the coupled vibration theory, dynamic behavior of steel bridge deck thin surfacing under rand moving vehicles is studied. A three-dimensional coupled model is carried out for the steel bridges deck thin surfacing and vehicle. A method based on modal superposition and state space technique is developed to solve dynamic response generated by vehicle-surfacing interaction. The dynamic responses of an actual steel bridge deck thin surfacing are studied. The results show that adding epoxy asphalt as a sub coat can improve interface adhesion strength, which would be designed as the interface layer of steel deck thin surfacing.

An advanced vehicle–slab track interaction model considering rail random irregularities

2017 ◽  
Vol 24 (19) ◽  
pp. 4592-4603 ◽  
Author(s):  
Lei Xu ◽  
Zhaowei Chen ◽  
Wanming Zhai
Keyword(s):  
Dynamic Model ◽  
Calculation Method ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dynamic Responses ◽  
Computational Time ◽  
Infinite Length ◽  
Slab Track ◽  
Rail Irregularity ◽  
Track Irregularity

This paper investigates a more advanced vertical vehicle–slab track interaction model (VTIM) by considering the discontinuity of track slabs, besides, it can be degenerated to the traditional two-dimensional model conveniently. Moreover, a cyclic calculation method (CCM) is further developed to solve infinite length calculations. On this basis, the proposed dynamic model and CCM are validated by comparing with the more comprehensive three-dimensional train–track model and fixed-point excitation method. Then, from aspects of probability statistics and frequency analysis, an illustrative example is particularly conducted to comprehensively characterize the dynamic responses of vehicle–slab track systems, in which the representative and realistic rail irregularity sets simulated by the track irregularity probabilistic model are used as the loading inputs. Results show that, with a low consumption of computational time and computer memory, the dynamic results derived from VTIM and CCM have a high accuracy, which indicates that the proposed dynamic model and calculation method can be efficiently and accurately used to analyze train–slab track interactions.

scholarly journals Effects of Differential Subgrade Settlement on Slab Track Deformation Based on a DEM-FDM Coupled Approach

2021 ◽  
Vol 11 (4) ◽  
pp. 1384
Author(s):  
Xuhao Cui ◽  
Rui Zhou ◽  
Gaoran Guo ◽  
Bowen Du ◽  
Hanlin Liu
Keyword(s):  
Contact Force ◽  
Three Dimensional ◽  
Coupled Model ◽  
Contact Forces ◽  
Railway Track ◽  
Slab Track ◽  
Maximum Value ◽  
Track System ◽  
Track Deformation ◽  
Maximum Contact

Slab track structures become deformed under the effects of differential subgrade settlement. According to the properties of the China Railway Track System (CRTS) II slab track on a subgrade, a three-dimensional (3D) coupled model based on both the discrete element method (DEM) and finite difference method (FDM) was developed. The slab track and subgrade were simulated using the FDM and DEM, respectively. The coupled model was verified. The deformation of the slab track and contact forces of gravel grains in the surface layer of the subgrade were studied under differential subgrade settlement. The effects of settlement wavelength, settlement amplitude, and other types of settlements were also discussed. The results demonstrate that the settlement amplitude and settlement wavelength of the subgrade have significant effects on track deformation. The deformation amplitude of the slab track increases nonlinearly with an increasing settlement amplitude of the subgrade. Increases in the settlement wavelength and amplitude of the subgrade significantly increase the maximum value of the contact force of the gravel grains in the subgrade. The maximum contact force of gravel grains near the boundaries of the settlement section can reach two to three times that of the unsettled condition, which makes it easy to accelerate the plastic settlement of the subgrade.

Three-Dimensional Finite Element Analysis Model of High-Speed Train-Track-Bridge Dynamic Interactions

2005 ◽  
Vol 8 (5) ◽  
pp. 513-528 ◽  
Author(s):  
Yong-Seon Lee ◽  
Sang-Hyo Kim ◽  
Jun Jung
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Coupling Effect ◽  
Resonance Effect ◽  
Three Dimensional ◽  
Dynamic Responses ◽  
Railway Track ◽  
Railway Bridge ◽  
Analysis Model ◽  
Element Analysis

The dynamic behavior is a complicated characteristic in analysis of a railway bridge when it is incorporated with the effect of railway track. Even though it is not an ignorable component, the coupling effect with the railway track in the dynamic response of a railway bridge has been ignored or just simplified in the past researches. Therefore, this study conducts a numerical analysis of track effect on the railway bridge, and the comparison between the dynamic responses with three-dimensional (3D) discrete support track model and those without it is examined. Dynamic amplitude incorporated with 3D track model is decreased when the train velocity goes up over 250 km/h. This phenomenon shows that the resonance effect has been shifted by the 3D track model, which results in the changes in dynamic characteristics of a railway bridge. Consequently, the coupling effect between bridge and track should be taken account for in the analysis of dynamic response of a railway bridge.

scholarly journals A Comparative Study on Vertical Dynamic Responses of Three Types of Elevated Railway Tracks Subjected to a Moving Train

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Li Shi ◽  
Xiaoqiang Ye ◽  
Pengfei Zhang ◽  
Lin Guo
Keyword(s):  
Theoretical Model ◽  
Comparative Study ◽  
Reaction Force ◽  
Dynamic Responses ◽  
Railway Track ◽  
Steel Spring ◽  
Slab Track ◽  
Ballastless Track ◽  
Different Types ◽  
Moving Train

A theoretical model incorporating the moving train, the railway track, and the elevated viaduct is established and then solved using periodic theory in this paper. The vertical wheel/rail forces and the dynamic responses of track and viaduct girder are obtained and compared for three different types of tracks, i.e., the double-block ballastless track, the rubber-pad floating slab track, and the steel-spring floating slab track. It is observed that the rubber-pad and steel-spring floating slab tracks can reduce more than 10% of the wheel/rail force and the reaction force at girder supports, when compared to those of the double-block ballastless track. Especially, the steel-spring floating slab track develops an uplifting force larger than the installation force of the fastening clip, which may cause failure of the rail fastening system.

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

Use of a three-dimensional model to predict heavy metal (copper) fluxes in the Oujiang estuary

2014 ◽  
Vol 69 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
Shasha Lu ◽  
Ruijie Li ◽  
Xiaoming Xia ◽  
Jun Zheng
Keyword(s):  
River Discharge ◽  
Water Surface ◽  
Three Dimensional ◽  
Measured Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Pollutant Concentrations ◽  
Suspended Sediment Concentrations ◽  
Adsorption Desorption ◽  
Good Agreement

Measuring pollutant concentrations in major tributaries is the standard method for establishing pollutant fluxes to the sea. However, this method is costly and difficult, and may be subject to a great deal of uncertainty due to the presence of unknown sources. This uncertainty presents challenges to managers and scientists in reducing contaminant discharges to water bodies. As one less costly method, a three-dimensional model was developed and used to predict pollutant fluxes to the sea. The sorptive contaminant model was incorporated into hydrodynamic and sediment models. Adsorption–desorption of copper by sediments in the Oujiang estuary were described using Henry's law. The model was validated using measured data for water surface elevations, flow velocity/direction, suspended sediment concentrations, and the proportion of copper sorbed to sediment. The validated model was then applied to predict fluxes of copper. Combined with the measured data, the copper concentration in the Oujiang River discharge was calculated as 13.0 μg/L and copper fluxes were calculated as 52 t in 2010. This copper flux prediction was verified using measured dissolved copper concentrations. Comparisons between the modeled and measured results showed good agreement at most stations, demonstrating that copper flux prediction in the Oujiang estuary was reasonably accurate.

3-D elastic coupling vibration and acoustical radiation characteristics of cracked gear under elastic support condition

2015 ◽  
Vol 23 (9) ◽  
pp. 1548-1568 ◽  
Author(s):  
Shao Renping ◽  
Purong Jia ◽  
Xiankun Qi
Keyword(s):  
Dynamic Response ◽  
Support System ◽  
Three Dimensional ◽  
Elastic Support ◽  
Dynamic Responses ◽  
Tooth Root ◽  
Support Condition ◽  
Elastic Boundary ◽  
Root Crack ◽  
Elastic Disc

According to the actual working condition of the gear, the supporting gear shaft is treated as an elastic support. Its impact on the gear body vibration is considered and investigated and the dynamic response of elastic teeth and gear body is analyzed. On this basis, the gear body is considered as a three-dimensional elastic disc and the gear teeth are treated as an elastic cantilever beam. Under the conditions of the elastic boundary (support shaft), combining to the elastic disk and elastic teeth, the influence of three-dimensional elastic discs on the meshing tooth response under an elastic boundary condition is also included. A dynamic model of the gear support system and calculated model of the gear tooth response are then established. The inherent characteristics of the gear support system and dynamics response of the meshing tooth are presented and simulated. It was shown by the results that it is correct to use the elastic support condition to analyze the gear support system. Based on the above three-dimensional elastic dynamics analysis, this paper set up a dynamics coupling model of a cracked gear structure support system that considered the influence of a three-dimensional elastic disc on a cracked meshing tooth under elastic conditions. It discusses the dynamic characteristic of the cracked gear structure system and coupling dynamic response of the meshing tooth, offering a three-dimensional elastic body model of the tooth root crack and pitch circle crack with different sizes, conducting the three-dimensional elastic dynamic analysis to the faulty crack. ANSYS was employed to carry out dynamic responses, as well as to simulate the acoustic field radiation orientation of a three-dimensional elastic crack body at the tooth root crack and pitch circle with different sizes.

Coupled Sea Ice-Ocean Model of the Arctic Ocean

1998 ◽  
Vol 120 (2) ◽  
pp. 77-84 ◽  
Author(s):  
I. V. Polyakov ◽  
I. Yu. Kulakov ◽  
S. A. Kolesov ◽  
N. Eu. Dmitriev ◽  
R. S. Pritchard ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Three Dimensional ◽  
Coupled Model ◽  
Ocean Model ◽  
Distribution Functions ◽  
Constitutive Law ◽  
Prognostic Models ◽  
The Arctic ◽  
The Arctic Ocean ◽  
Ocean Layer

A fully prognostic coupled ice-ocean model is described. The ice model is based on the elastic-plastic constitutive law with ice mass and compactness described by distribution functions. The ice thermodynamics model is applied individually to each ice thickness category. Advection of the ice partial mass and concentrations is parameterized by a fourth-order algorithm that conserves monotonicity of the solution. The ocean is described as a three-dimensional time-dependent baroclinic model with free surface. The coupled model is applied to establish the Arctic Ocean seasonal climatology using fully prognostic models for ice and ocean. Results reflect the importance of the ice melting/freezing in the formation of the thermohaline structure of the upper ocean layer.

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