|Alternative Title||Effect of Laser Textured Surface on Adhesion Coefficient of High-speed Wheel/Rail Contact under Water/Ice Lubrication|
|Place of Conferral||北京|
|Keyword||高速列车 黏着系数 形貌取向 混合润滑|
Adhesion property has a key effect on traction and brake of train running. It is important to maintain safety and stability reduce contact fatigue and surface scratching, and low the risk of derailment of trains. The adhesion property between wheel and rail is mainly reflected by adhesion coefficient. There are many factors that affect the adhesion coefficient, such as slip rate, speed, lubricant characteristics, surface roughness and roughness orientation of wheel/rail.
In this paper, the effect of laser texturing wheel surface orientation on adhesion properties of wheel/rail of high-speed train under water lubrication and ice lubrication were studied. According to the theory of elastohydrodynamic lubrication, the wheel/rail contact could be treated as a mixed lubrication under water lubrication. The variation of adhesion coefficient with slip ratio, speed was computed based on the unified Reynolds equation method, where the wheel surface was wih and without laser texturing patterns, i.e., longitudinal, transverse, rhombus, and random pattern. For minus temperature with ice lubrication, the dimensionless pressure distributions with random pattern of wheel surface were computed at first. Then the contact area was divided into mixed area and solid area, i.e. steel-ice area, based on the phase diagram of ice and the theory of pressure melt. In the mixed area it was still computed by unified Reynolds equation method, while in the steel-ice area it was computed by degraded Reynolds equation, i.e. Hertz equation. The total adhesion coefficient was the sum of the two adhesion coefficients of the areas. Finally the adhesion coefficient with three laser texturing wheel patterns, such as longitudinal, transverse, rhombus was computed under the conditions of 0.02 slip ratio and 0~-21℃ temperature region.
The conclusions of this paper were the following:
(1) Under the condition of water lubrication, the laser texturing patters have apparently effects on increasing adhesion. The adhesion coefficient of rhombus pattern is the most one, and that of transverse is better than that of longitudinal;
(2) The calculation of the dimensionless pressure distribution shows that the load ratio is the main factor to affect adhesion property. The load ratio is the ratio of asperity contact pressure to the total pressure. Laser texturing could effectively lift up the load ratio;
(3) Under the condition of ice lubrication, the adhesion coefficient decreases significantly with the same slip ratio and speed. The adhesion coefficient increases with the increase of ice temperature;
(4) The laser texturing patterns still enhance apparently on adhesion coefficient under the conditions of ice lubrication.
Key words: High-speed train, Adhesion coefficient, roughness orientation, Mixed lubrication
|王保安. 激光毛化形貌对高速轮轨水润滑及冰润滑 黏着系数的影响[D]. 北京. 中国科学院大学,2018.|
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