Wei W.,Dalian Jiaotong University |
Zhao X.-B.,Dalian Jiaotong University |
Jiang Y.,Qiqihar Railway Rolling Stock Group Co. |
Zhang J.,Dalian Jiaotong University
Tiedao Xuebao/Journal of the China Railway Society | Year: 2012
Longitudinal impact of the long train is the bottleneck of developing heavy haul trains. The source of the impact is braking propagation. The braking characteristics test method cannot satisfy the need of longitudinal dynamics simulation of various train formations, especially for the train with multi-locomotives and the brake vent device at train-tail. To get train braking performance of wider application becomes the primary problem in simulation of heavy haul longitudinal dynamics. The integrated model of air brake and longitudinal dynamics of the train was developed. Being based on the message mechanism, this model can realize synchronous simulation of the air brake system and longitudinal train dynamics, and it can change the train order when the train is running. The basic principle of synchronous simulation of air flow in the brake system and longitudinal train dynamics was put forward. The calculation methods of the air flow in the brake pipe, pressure in volume, traction force, electric brake force, buffer characteristics, and friction factor of wheel and brake shoe etc. were introduced. The simulation results were compared with the braking characteristics, longitudinal force, braking distance and braking time acquired in experiments with 10000 t and 20000 t trains. Good coincidence was proved. The proposed system is adapted to suit the need of simulating for important parameters such as the brake force and coupler force etc. of trains of any formation running on any type of railway lines in China. This provides a research method for optimization of brake systems and buffer performance.
Wang K.,Harbin University of Science and Technology |
Guo E.,Harbin University of Science and Technology |
Cao G.,Harbin University of Science and Technology |
Wang L.,Harbin University of Science and Technology |
And 3 more authors.
China Foundry | Year: 2013
The bogie made of Grade B+ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the fracture failure occurred. Because Al was added for the final deoxidation during the smelting process of the Grade B+Steel, residual Al existed to some extent in the castings. High residual Al content in the bogie casting was presumed to be the reason for the fracture. In this work, the influence of residual Al content in the range of 0.015wt.% to 0.3wt.% on the microstructure and mechanical properties of the Grade B+ Steel was studied. The experimental results showed that when the residual Al content is between 0.02wt.% and 0.20wt.%, the mechanical properties of the steel meet the requirements of technical specification for heavy haul train parts, and the fracture is typical plastic fractures. If the residual Al content is less than 0.02wt.%, the microstructures are coarse, and the mechanical properties can not meet the demand of bogie steel castings. When the residual Al content is more than 0.2wt.%, the elongation, reduction of area, and low-temperature impact energy markedly deteriorate. The fracture mode then changes from plastic fracture to cleavage brittle fracture. Therefore, the amount of Al addition for the final deoxidation during the smelting process must be strictly controlled. The optimum addition amount needs to be controlled within the range of 0.02wt.% to 0.20wt.% for the Grade B+Steel.
Wei Y.,Beijing Jiaotong University |
Wei J.,Beijing Jiaotong University |
Yu Y.,Qiqihar Railway Rolling Stock Group Co. |
Liu H.,Qiqihar Railway Rolling Stock Group Co.
Zhongguo Tiedao Kexue/China Railway Science | Year: 2014
According to the analysis of the main technical parameters for existing coal open-top wagons with high axle load in China and the USA, with the comprehensive consideration of such factors as the specific volume of vehicle, vehicle weight per extended metre and bridge adaptability, based on C96 coal open-top wagon, and by making the most of rolling stock gauge for China's standard gauge railways, theoretical calculation suggests that the maximum reasonable axle load of new coal open-top wagon(referred to as new open-top wagon) can be improved to 32.32 t and the weight per extended metre increased to 9.51 t·m-1. Compared with C80 and C96 coal open-top wagon, the carrying capacity of single vehicle for the new open-top wagon improves significantly, and the number of cars (length) has a clear reduction. Compared with American BethGon coal open-top wagon, their axle loads are very close, while the coefficient of dead weight for the new open-top wagon is larger, so lightweight design of bodywork is needed with the consideration of vehicle structural reliability. The weight per extended metre of the new open-top wagon is slightly larger than the recommended value of Jinzhongnan Passageway bridges' design live load 9.30 t·m-1, so its adaptability with bridges should be further tested. The new open-top wagon's gravity center height of wagon loaded under both full load and full volume conditions reaches 2057 mm, which exceeds the standard of 2000 mm for the limited height of the loaded railway wagons' gravity center, and modification for the standard is suggested.