Research on Adhesion and Non-Adhesion Braking Characteristics for High-Speed Train

2011 ◽  
Vol 121-126 ◽  
pp. 3437-3443
Author(s):  
Hai Jun Wang ◽  
Jing Zeng ◽  
Guang Bing Luo ◽  
Zhuan Hua Liu
Keyword(s):  
High Speed ◽  
The State ◽  
High Speed Train ◽  
Braking Performance ◽  
Area Method ◽  
Emergency Braking ◽  
Braking Distance

The emergency braking deceleration and braking distance of high-speed train were studied under the conditions of adhesion brake on dry and humid rail surfaces, and adhesion and non-adhesion composite brake on humid rail surface. The average emergency braking deceleration was calculated by the area-method. The results show that the braking performance is affected significantly by the wheel/rail adhesion state and the braking performance of high-speed train can be improved by applying the adhesion and non-adhesion composite brake in the state of humid rail surface.

Open Innovation in France

2011 ◽  
pp. 308-329 ◽  
Author(s):  
Rachael J. Ritchie ◽  
Keith C. Culver
Keyword(s):  
21St Century ◽  
Open Innovation ◽  
High Speed ◽  
Innovation System ◽  
The State ◽  
High Speed Train ◽  
Innovation Cluster ◽  
National Competitiveness ◽  
Accelerate Development

France has long been associated with a state-directed “dirigiste” model of linear R&D focussed on large programmes such as development of the TGV high-speed train. Contemporary France has, however, largely left the state-centered model behind, introducing a range of devices since the turn of the 21st century aimed at opening French innovation to international and cross-sectoral collaboration for increased productivity and national competitiveness. This case study traces the opening of the French innovation system and the way one new academic, industrial and government collaboration aims to make use of new features of the system to accelerate development of an eco-innovation cluster focussed on cities of the future.

The Vibration Response Analysis about High-Speed Train’s Braking Wing

2012 ◽  
Vol 226-228 ◽  
pp. 102-105
Author(s):  
Wen Qing Zhu ◽  
Yang Yong Zhu
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Rapid Development ◽  
Response Analysis ◽  
High Speed Train ◽  
High Speed Railway ◽  
Emergency Braking ◽  
Finite Element Software ◽  
High Speed Trains ◽  
Aerodynamic Brake

With the rapid development of high-speed railway in China, the aerodynamic brake is very likely to be an important emergency braking mode of high-speed train in the future. This paper takes aerodynamic braking wing as the object, and uses the finite element software to divide the meshes, then analyses the model influenced by static stress. After simulating the vibratory frequency response of the model in the flow field, it finds that the largest deformation happens in the middle of the upper edge of the wind wing, when the wind speed gets to 500km/h and the load frequency to 4Hz. Some conclusions of this thesis can provide reference for researching the applying the aerodynamic brake in the high-speed trains and laying the foundation for solving the riding and braking safety problems.

scholarly journals Hydrogeological assessment of non-linear underground enclosures

2021 ◽  
Author(s):  
Estanislao Pujades
Keyword(s):  
High Speed ◽  
Retaining Walls ◽  
The State ◽  
High Speed Train ◽  
Diagnostic Plots ◽  
Pumping Wells ◽  
Groundwater Response ◽  
Non Linear ◽  
Effective Conductance ◽  
Using Data

Excavations below the water table are usually undertaken by combining the protection of retaining walls with dewatering by pumping wells. Severe difficulties may arise if the retaining walls have defects. Therefore, their state must be determined and, if needed, the defects repaired or the dewatering system redesigned. The state of underground retaining walls can be evaluated using hydrogeological methods, but these methods are well-established only for linear excavations. The objective of this work is to propose a procedure to evaluate the state of non-linear underground enclosures by analysing the groundwater response to pumping inside the enclosure. The proposed method, which is based on diagnostic plots (derivative of drawdown with respect to the logarithm of time), allows (1) determining if an underground non-linear enclosure has isolated openings or numerous defects and (2) computing its effective conductance or effective hydraulic conductivity. The methodology is tested with data collected during the excavation of a shaft required for the construction of the high speed train (HST) tunnel in Barcelona, Spain. The procedure can be applied using the wells drilled for dewatering. Although a test before the excavation is recommended to evaluate the underground retaining walls (Watertightness Assessment Test), the method can be applied using data collected at the beginning of the dewatering stage.

Investigation on the Aerodynamic Efficiency of Braking Spoiler for High Speed Train Applications

2020 ◽  
pp. 2150009
Author(s):  
M. Vikraman ◽  
J. Bruce Ralphin Rose ◽  
S. Ganesh Natarajan
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
High Speed Train ◽  
Passenger Cars ◽  
High Speed Rail ◽  
Braking Performance ◽  
Simulation Tools ◽  
Drag Forces ◽  
Differential Drag

The demand for high speed rail networks is rapidly increasing in developing countries like India. One of the major constraints in the design and implementation of high speed train is the braking efficiency with minimum friction losses. Recently, the aerodynamic braking concept has received good attention and it has been incorporated for high speed bullet trains as a testing phase. The braking performance is extremely important to ensure the passenger safety specifically for the trains moving at more than 120[Formula: see text]km/h. In this paper, an Indian train configuration WAP7 (wide gauge AC electric passenger, Class 7) has been assumed with the locomotive and one passenger car. Aerodynamic braking system design is done by opening a spoiler over the train to amplify the aerodynamic drag at high speeds. The magnitude of braking force depends on the position and orientation of the braking spoiler. It creates differential drag forces at various deflection angles to decelerate the trains instantaneously in proportion to the running speeds. Drag created by the braking spoiler is observed numerically with the help of CFD simulation tools for further validation through wind tunnel experiments. Striking aerodynamic results are obtained with and without braking spoilers on the passenger cars and the spoiler at 40[Formula: see text]–50[Formula: see text] orientation makes greater drag coefficient as compared to the other angles.

FEM for Brake Discs of SiC 3D Continuous Ceramic Reinforced 7075 Aluminum Alloy for CRH3 Trains Applying Emergency Braking

2011 ◽  
Vol 120 ◽  
pp. 51-55 ◽  
Author(s):  
Liang Yu ◽  
Yan Li Jiang ◽  
Sen Kai Lu ◽  
Hong Qiang Ru ◽  
Ming Fang
Keyword(s):  
Aluminum Alloy ◽  
Thermal Stress ◽  
High Speed ◽  
Distribution Model ◽  
Transient Temperature ◽  
Brake Disc ◽  
Three Dimension ◽  
High Speed Train ◽  
Emergency Braking ◽  
Aluminum Alloy 7075

The shaft disc prepared with SiC 3D continuous ceramic frame reinforced aluminum alloy 7075 (3D-SiC/Al) composite of the CRH3 high speed train with a speed at 250 km/h was chosen as the research object, and the course of emergency brake was simulated by Cosmos. A three dimension model was established, the way of applying loads were discussed, and the temperature field and thermal stress field were obtained. The result shows that the highest temperature appears at about 57 s since braking and the value is about 373 °C. The biggest stress is about 237 MPa, appearing at about 51 s since braking, the regions distribute at the surface corresponding with the radiating ribs, and near the inner diameter. The hoop stress is larger than other directions. The result shows that the thermal stress duce to the transient temperature distribution model is released well for the distribution of the 3D continuous ceramic frame reinforced aluminum alloy 7075 structure compares with the conventional brake disc, which can satisfy the requirement of the shaft disc of the high speed train with a speed at 250 km/h applying emergency braking.

Study on High-Speed Train Terminal Speed Based on Adhesion Utilization

2012 ◽  
Vol 184-185 ◽  
pp. 516-520
Author(s):  
Hai Jun Wang ◽  
Jing Zeng
Keyword(s):  
High Speed ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
High Speed Train ◽  
Area Method ◽  
Adhesion Coefficient ◽  
Development Level ◽  
Necessary And Sufficient ◽  
Traction Power

The terminal speed of wheel/rail train is being concerned in the era of high-speed train. The number of terminal speed represents development level of wheel/rail train. In this study, the calculation formulas of basic resistance and calculation adhesion of the "Harmony" EMU were used. It was assumed that the traction power is enough large, and the terminal speed of high-speed train was obtained by calculating for dry rail surface and humid rail surface. The average terminal speed was calculated by the area-method. Randomly variational adhesion coefficient was simulated, and the necessary and sufficient conditions for the terminal speed were derived.

A New Design Tool for Tire Braking Performance Evaluations

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Srikanth Sivaramakrishnan ◽  
Yaswanth Siramdasu ◽  
Saied Taheri
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Design Tool ◽  
Tire Model ◽  
Wheel Slip ◽  
Element Analysis ◽  
Braking Performance ◽  
Early Evaluation ◽  
Braking Distance ◽  
Computationally Intensive

The objective of this study is to understand the influence of high frequency tire vibrations induced due to road disturbances and brake torque cycling due to anti-lock braking system (ABS) on braking performance. Under these conditions, transient dynamics of the tire play a crucial role in the generation of braking force. To implement this, a dynamic tire model was developed using a rigid ring tire and a tandem elliptical cam design for the enveloping model. This tire model is validated using experimental data obtained from high-speed cleat tests on a fixed axle. The validated tire model is then integrated with a quarter vehicle and a commercial grade rule-based ABS model to evaluate braking performance with and without a road cleat, which can provide a high frequency disturbance. Simulation results show that the presence of a 1 cm cleat causes large variations in wheel slip, consequently increasing the braking distance. The developed tool will help both tire and vehicle manufactures for quick and early evaluation of braking performance without computationally intensive finite element analysis (FEA) tools.

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