Ground vibrations induced by InterCity/InterRegion trains: a numerical prediction based on the multibody/finite element modeling approach

2016 ◽  
Vol 22 (20) ◽  
pp. 4192-4210 ◽  
Author(s):  
Georges Kouroussis ◽  
Juliette Florentin ◽  
Olivier Verlinden
Keyword(s):  
High Speed ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Element Model ◽  
Numerical Prediction ◽  
Soil Conditions ◽  
Vehicle Speed ◽  
Ground Vibrations ◽  
Using Data ◽  
Main Components

This present paper aims to identify the main components which influence the generation and the propagation mechanisms of railway-induced ground vibrations. It is based on numerical assessments of ground vibrations on the L161 line that runs through Brussels Capital Region, Belgium. The objective is twofold. First, using data collection at a Brussels site, a numerical prediction model is built up. It is based on a two-step approach, recently validated in tramway and high-speed train cases and improved by an accurate description of the foundation. The vehicle/track/foundation and soil subsystems are treated successively. A key advantage of the new approach is that it is capable of including the effect of soil conditions in the vehicle/track simulation. The vehicle is modeled with the help of the multibody strategy. The soil is a three-dimensional finite/infinite element model, with a complex geometry on the surface and inclined soil layers. The track model includes a rail joint defect. The model is eventually validated against experimental data. Then, a sensitivity analysis on parameters of the studied site is performed. The vehicle and foundation modeling are discussed, along with the influence of local defects and vehicle speed variation on ground vibrations.

scholarly journals Saturated Ground Vibration Analysis Based on a Three-Dimensional Coupled Train-Track-Soil Interaction Model

2019 ◽  
Vol 9 (23) ◽  
pp. 4991 ◽  
Author(s):  
Li ◽  
Su ◽  
Kaewunruen
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Interaction Model ◽  
Ground Vibration ◽  
Field Measurements ◽  
Soil Conditions ◽  
Layered Soils ◽  
Train Track ◽  
Dynamic Interactions ◽  
Vibration Responses

A novel three-dimensional (3D) coupled train-track-soil interaction model is developed based on the multi-body simulation (MBS) principle and finite element modeling (FEM) theory using LS-DYNA. The novel model is capable of determining the highspeed effects of trains on track and foundation. The soils in this model are treated as saturated media. The wheel-rail dynamic interactions under the track irregularity are developed based on the Hertz contact theory. This model was validated by comparing its numerical results with experimental results obtained from field measurements and a good agreement was established. The one-layered saturated soil model is firstly developed to investigate the vibration responses of pore water pressures, effective and total stresses, and displacements of soils under different train speeds and soil moduli. The multi-layered soils with and without piles are then developed to highlight the influences of multi-layered soils and piles on the ground vibration responses. The effects of water on the train-track dynamic interactions are also presented. The original insight from this study provides a new and better understanding into saturated ground vibration responses in high-speed railway systems using slab tracks in practice. This insight will help track engineers to inspect, maintain, and improve soil conditions effectively, resulting in a seamless railway operation.

LED-Based 3-DMD Volumetric 3D Display

2014 ◽  
Vol 596 ◽  
pp. 442-445
Author(s):  
Chang Long Jing ◽  
Qi Bin Feng ◽  
Ying Song Zhang ◽  
Guang Lei Yang ◽  
Zhi Gang Song ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
High Speed ◽  
Three Dimensional ◽  
Human Vision ◽  
3D Display ◽  
Video Projector ◽  
High Speed Video ◽  
University Of Technology ◽  
Measurement Results ◽  
Main Components

A solid-state volumetric true 3D display developed by Hefei University of Technology consists of two main components: a high-speed video projector and a stack of liquid crystal shutters. The shutters are based on polymer stabilized cholesteric texture material, presenting different states that can be switched by different voltage. The high-speed video projector includes LED-based light source and tree-chip digital micro-mirror devices modulating RGB lights. A sequence of slices of three-dimensional images are projected into the liquid crystal shutters locating at the proper depth, forming a true 3D image depending on the human vision persistence. The prototype is developed. The measurement results show that the screen brightness can reach 149 nit and no flickers can be perceived.

scholarly journals Vibration Response Characteristics of the Cross Tunnel Structure

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Jinxing Lai ◽  
Kaiyun Wang ◽  
Junling Qiu ◽  
Fangyuan Niu ◽  
Junbao Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Vibration Response ◽  
Shield Tunnel ◽  
Tunnel Structure ◽  
Response Characteristics ◽  
Vehicle Load ◽  
Metro Tunnel

It is well known that the tunnel structure will lose its function under the long-term repeated function of the vibration effect. A prime example is the Xi’an cross tunnel structure (CTS) of Metro Line 2 and the Yongningmen tunnel, where the vibration response of the tunnel vehicle load and metro train load to the structure of shield tunnel was analyzed by applying the three-dimensional (3D) dynamic finite element model. The effect of the train running was simulated by applying the time-history curves of vibration force of the track induced by wheel axles, using the fitted formulas for vehicle and train vibration load. The characteristics and the spreading rules of vibration response of metro tunnel structure were researched from the perspectives of acceleration, velocity, displacement, and stress. It was found that vehicle load only affects the metro tunnel within 14 m from the centre, and the influence decreases gradually from vault to spandrel, haunch, and springing. The high-speed driving effect of the train can be divided into the close period, the rising period, the stable period, the declining period, and the leaving period. The stress at haunch should be carefully considered. The research results presented for this case study provide theoretical support for the safety of vibration response of Metro Line 2 structure.

Thermal Analysis and Optimization Design on Spindle Bearing of GSCK200A CNC Lathe

2011 ◽  
Vol 314-316 ◽  
pp. 1760-1763
Author(s):  
Le Ping Liu ◽  
Guo Hong Deng
Keyword(s):  
High Speed ◽  
Thermal Deformation ◽  
Optimization Design ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Clearance ◽  
Spindle Bearing ◽  
Heat Transfer Theory ◽  
Cnc Lathe ◽  
Three Dimensional Finite Element

Establish the three-dimensional finite element model of GSCK200A type High-speed & high-precision CNC Lathe spindle bearing, based on tribology and heat transfer theory, using ANSYS to analyze the corresponding temperature field and thermal deformation of spindle bearing in steady working state, according to this thermal deformation to obtain decrease volume of radial clearance, and the installation clearance optimization scheme is putted forward.

Prediction of Turbulent Rough-Wall Skin Friction Using a Discrete Element Approach

1985 ◽  
Vol 107 (2) ◽  
pp. 251-257 ◽  
Author(s):  
R. P. Taylor ◽  
H. W. Coleman ◽  
B. K. Hodge
Keyword(s):  
Turbulent Flows ◽  
Three Dimensional ◽  
Element Model ◽  
Discrete Element ◽  
Boundary Layer Flows ◽  
Basic Principles ◽  
Roughness Model ◽  
Roughness Elements ◽  
Element Approach ◽  
Using Data

A discrete element model for turbulent flow over rough surfaces has been derived from basic principles. This formulation includes surface roughness form drag and blockage effects as a constituent part of the partial differential equations and does not rely on a single-length-scale concept such as equivalent sandgrain roughness. The roughness model includes the necessary empirical information on the interaction between three-dimensional roughness elements and the flow in a general way which does not require experimental data on each specific surface. This empirical input was determined using data from well-accepted experiments. Predictions using the model are compared with additional data for fully-developed and boundary layer flows. The predictions are shown to compare equally well with both transitionally rough and fully rough turbulent flows without modification of the roughness model.

Lamb Wave Based Damage Identification in Structures With Complex Geometry

2008 ◽  
Author(s):  
Xi Lu ◽  
Fucai Li ◽  
Guang Meng ◽  
Lin Ye ◽  
Ye Lu
Keyword(s):  
Finite Element ◽  
Lamb Wave ◽  
Damage Identification ◽  
Complex Geometry ◽  
Lamb Waves ◽  
Three Dimensional ◽  
Quantitative Relationship ◽  
Element Model ◽  
Crack Location ◽  
Propagation Behavior

Structural health monitoring (SHM) plays a significant role in terms of fatigue life and damage accumulation prognostics. SHM for structures with complex geometry are much more practical in engineering applications. In this paper, complex aluminium alloy structures with “U” shape section were evaluated in terms of both finite element method (FEM)- and experiment-based Lamb wave analysis for the purpose of damage detection and identification. In the FEM-based analysis, three-dimensional finite element model was established to simulate the propagation behavior of Lamb wave in the structures. On the other hand, in the experiments, piezoelectric (PZT) wafers, functioning as both actuator and sensor, were used to generate Lamb waves propagating in the structures and collect the Lamb wave signals from the complex structures. Quantitative relationship between crack location and the reflection coefficient was constructed by taking advantage of continuous wavelet transform (CWT) and Hilbert transform (HT), which are based on the collected Lamb wave signals. Furthermore, the differences between simulated and experimental results in respect of crack severity evaluation and the reasons were discussed.

A Study of Thermohydrodynamic Features of Multi Wound Foil Bearing Using Lobatto Point Quadrature

2008 ◽  
Author(s):  
Kai Feng ◽  
Shigehiko Kaneko
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Iteration Process ◽  
Element Model ◽  
Air Bearings ◽  
Foil Bearing ◽  
Deformation Equation ◽  
Wide Range

The applications of foil air bearings, which are recognized to be the best choice for oil free applications, have been extended for use in a wide range of turbo-miachineries with high speed and high temperature. Lubricant temperature becomes an important factor in the performance of foil air bearings, especially at high rotational speeds and high loads or at high ambient temperature. However, most of the published foil air bearing models were based on the isothermal assumption. This study presents a thermohydrodynamic analysis (THD) of Multi Wound Foil Bearing (MWFB), in which the Reynolds’ equation is solved with the gas viscosity as a function of temperature that is obtained from the energy equation. Lobatto point quadrature, which was proposed by Elrod and Brewe and introduced into compressible calculation by Moraru and Keith, is utilized to accelerate the iteration process with a sparse mesh across film thickness. A finite element model of the foil is used to describe the foil elasticity. An iterative procedure is performed between the Reynolds’ equation, the foil elastic deformation equation and the energy equation, until the convergence is achieved. A three-dimensional temperature prediction of air film is presented and a comparison of THD to isothermal results is made to emphasize the importance of thermal effects. Finally, published experimental data are used to validate this numerical solution.

Electromagnetic torque and strength analysis of combination rotor in high speed PMSM

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1019-1027
Author(s):  
Hao Lin ◽  
Haipeng Geng ◽  
Lie Yu ◽  
Hao Li ◽  
Sheng Feng ◽  
...  
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Permanent Magnet Synchronous Motor ◽  
Three Dimensional ◽  
Analytical Calculation ◽  
Element Model ◽  
Strength Analysis ◽  
Electromagnetic Torque ◽  
Foil Bearings ◽  
Three Dimensional Finite Element

For a high-speed permanent magnet synchronous motor supported by air foil bearings, analyzing the influence of the electromagnetic torque on the strength of the combination rotor was necessary. In this study, the electromagnetic torque was obtained using the analytical calculation and the finite element simulation. The contact interface stress analytical equation affected by the electromagnetic torque was elaborated. A three-dimensional finite element model simulating the combination rotor was constructed, and the stress calculations were performed. The strength of the combination rotor met the design requirement. It properly reflected the characteristics of the electromechanical analysis in the combination rotor. The operation experiments were realized to verify the electromagnetic performance and the strength of the combination rotor. The simulation and experimental results were significant for the electromechanical design and analysis of the combination rotor.

Thermohydrodynamic Study of Multiwound Foil Bearing Using Lobatto Point Quadrature

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Kai Feng ◽  
Shigehiko Kaneko
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Iteration Process ◽  
Element Model ◽  
Air Bearings ◽  
Foil Bearing ◽  
Wide Range ◽  
Air Film

The applications of foil air bearings have been extended for use in a wide range of turbomachineries with high speed and high temperature. Lubricant temperature becomes an important factor in the performance of foil air bearings, especially at high rotational speeds and high loads or at high ambient temperature. This study presents a thermohydrodynamic (THD) analysis of multiwound foil bearing, in which the Reynolds’ equation is solved with gas viscosity as a function of temperature that is obtained from the energy equation. Lobatto point quadrature is utilized to accelerate the iteration process with a sparse mesh across film thickness. A finite element model of the foil is used to describe the foil elasticity. An iterative procedure is performed between the Reynolds equation, the foil elastic deflection equation, and the energy equation until convergence is achieved. A three-dimensional temperature prediction of air film is presented, and a comparison of THD to isothermal results is made to emphasize the importance of thermal effects. Finally, published experimental data are used to validate this numerical solution.

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