| With the development of national economy in our country,it is imminent to improve the efficiency of railway freight transportation,so the development of heavy haul railway is the inevitable trend.In recent years,the development of the heavy haul railway is always gradually accelerating in our country.The vehicle axle load and the train length are also improved continuously.And annual volume of heavy haul railway has reached several hundred million tons,such as Datong-Qinhuangdao Heavy Haul Line and Shuohuang Heavy Haul Line.All of these make the heavy haul railway bear to more and more tests.Turnout is the weak link of heavy haul line,especially the switch rail.The average service life of the curved switch rail is about 10 to 30 million tons which is much less than the common rail and it's only about one-fifth of the frog.So the service life of the switch rail is always the weakness in the heavy haul railway.Because of the frequent replacement of switch rail,it brings a heavy burden on the maintenance and greatly influences the efficiency of railway transportation.As a result,the switch rail has been one of the bottleneck of developing heavy haul railway technology.And optimizing geometrical structure constantly and prolonging the service life of switch rail has been the inevitable trend.In order to investigate the NO.12 curved switch rail with CHN75 rail in Datong-Qinhuangdao heavy haul railway,some wheel profiles and switch rail profiles aremeasured by using the wheel-rail profile admeasuring apparatus.And three dimernsional elastic-plastic contact finite element models with the measured profiles are established to study the contact behavior between wheel set and switch rail in different working conditions.The detailed analysis on the changing rules of the maximum equivalent stress and contact patches are conducted.Based on the numerical results,the geometric parameters optimization scheme of switch rail is presented,and the scheme has been validated theoretically.In this paper,the study of rail cant has proved that setting the appropriate rail cant parameter of NO.12 curved switch rail could improve the performance of wheel/rail contact when the wagon passing the switch rail.It is also good to protect the head of the switch rail and reduces the direct impact from the wheel flange and the tread to the switch rail.After comparing different schemes of switch rail cant parameter,the numerical results indicate that the maximum equivalent stress under the 1/40 rail cant is much smaller than others and the contact performance is the best.This is helpful to reduce switch rail wear.The numerical results could provide a basis for optimizing geometric parameters of switch rail.In the research on the the profile of switch rail,the contact behavior between wheel set and curved switch rail with profiles in different wear stages.After comparing the calculated results with the actual situation,the abrasion law of switch rail in the process of actual use is obtained and the reason of this phenomenon is analyzed.Then several plans of optimizing the switch rail profile are put forward on the basis of contact behavior between wheel set and switch rail with different wear stages profiles,and the new designed profile is validated theoretically by analyzing the wheel/rail contact behavior such as the maximum equivalent stress and contact patches.Through establishing the three dimensional elastic-plastic contact finite element model of dynamic gauge optimization in heavy haul switch rail,the different contact behavior of the vehicle passing switch rail is studied and the in-depth analysis of the reason is carried out.The different gauge widening schemes have been obtained by changing the value of widening.Besides the wheel/rail contact performance in each working conditions is analyzed by the simulation and comparison.All of the numerical results could provide a guideline for the application of dynamic gauge optimization for the switch rail in heavy haul railway. |
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