Rail Selection Method Based On The Competition Between Fatigue And Wear

Railway, a national important infrastructure, channel for materials transportation and the most popular kind of communications, plays an important role in the integrated transportation system. With the rapid expansion from operation mileage,speed and traffic density of the railway, the rolling contact fatigue and wear of the rail have become more and more prominent.The rolling contact fatigue and wear are the two main types of rail damage, and there is a competitive relationship between them. On the basis of understanding the generating mechanism of rail rolling contact fatigue and wear, the “layer ” fatigue crack initiation prediction model based on ratchet effect and wear calculation model were established. Everyone knows that the rolling contact fatigue crack initiation generally take place near the rail surface and wear exist on the rail surface in big friction coefficient circumstance. Using the above models, rail deterioration law and rail damage types can be predicted under cyclic loading by quantitative passing weight. Then, according to the usage of different rails, a set of alternative rails,possessing different types of steel rail respectively, were chosen. Through the medium of friction coefficient, this paper summarized the law and made six kinds of calculation work conditions, after studying the rail response under different stress environment. Finally, by predicting the deterioration law of rails under various conditions, judging the rail damage type, and making corresponding maintenance strategies, the paper primarily selected the selection of rail type. Furthermore,the paper built LCC calculation model and consider reuse of rail. The optimization of the rail type’s selection was completed from the comprehensive perspective of economy and technology.The conclusions are made by being compared and analyzed with the data.(1)The positions of the maximum shear stress and the maximum and minimum plastic deformation in the rail are determined by friction coefficient. The corresponding position of the value is 3 mm lower than the top of the rail when thefriction coefficient is less than 0.3. The position is closing to the rail surface with the growing of friction coefficient.(2)In the line for passenger and freight transportation, when the friction coefficient changes between 0.3 and 0.5 and wheel-rail contact state is one-point contact, the 60 kg/m hot rolled U75 V steel rail has better safety and economy in the section with a large proportion of passenger traffic. Under the same conditions, the 60kg/m U75 V steel rail with heat treatment has better safety and economy in the section with a large proportion of freight traffic.(3)As for the use of rail, second use of rail has a good advantage in economy.This measurement can save 19.3~ 40.9 percent of cost. By being analyzed, the cost of rail used by freight train is three times expensive than the passenger train. As for the analysis with the life cycle cost of the rail, the maintenance cost is 80 percent of the total cast. The key point to select the rail is to reduce the rail maintenance. With second use of the rail, the minimum cost of the freight train is 0.052 326 yuan per ton.The corresponding friction coefficient is 0.300. The type of the rail is 60 kg/m U75 V steel rail with heat treatment used for the train with 25 t axle load at the speed of 100km/h. The minimum cost of the passenger train is 0.005 275 yuan per ton. The corresponding friction coefficient is 0. 300. The type of the rail is 60 kg/m U75 V steel rail with heat treatment used for the train with 16 t axle load at the speed of 120 km/h.