Study On Heavy-Haul Rail Grinding Profile Optimization And Design Based On Contact Stress Analysis

Today, the heavy-haul transportation is one of the main development directions of railway transportation, as the artery of transportation which plays a very important role in the social and economic development. Due to the impacts of constantly increased loads of heavy-duty train axles, serious abrasion, and stronger contact stress between vehicle wheels and tracks, the service life of steel rail and the running safety of train will be sharply effected. Nowadays, most trims of rail profile are realized by rail grinding. The main heavy-haul railway world powers have taken the design of rail grinding’s target profile very seriously. It is supposed to have guiding significance for increasing the railway’s capacity by using rail profile optimization and reducing the contact stress between wheels and tracks.This paper puts forward a rail profile grinding optimizing method based on an analysis of the contact stress between wheel and rail. According to the geometry relationship of the contacting wheel and rail, this article uses APDL language to establish its finite element parametric model. Within the scope of the wheel set’s dynamic transversal, the paper obtains the biggest contact stress distribution between wheel and rail that based on the model. The contact stress between wheel and rail is treated as the direct optimizing goal, and keeping it in mind, a corresponding rail profile optimizing method is established and the program of the optimization is given. With reference to the big contact stress between wheel and rail of Chinese heavy-haul railway and its serious damage, this article uses the optimizing method respectively to optimize the overloading line standard rail and the worn-type 75kg/m one, and got the pre grinding target profile which matched with the given wheel as well as the reparative polishing one. This article makes full use of ANSYS finite element analysis software to carry out comparative analysis of the contact geometry and contact mechanics performance which comes from optimized rail and not optimized one. The results shows that the optimized rail matched with wheel, and on the premise of meeting other contact characteristics and dynamic performance, it can significantly reduce the maximum contact stress between wheel and rail. The results respectively provides a theoretical guidance towards the design of line rail’s pre-grinding and the target type surface’s repaired grinding, has a positive significance on prevention of rail surface’s rolling contact fatigue and extended the rail replacement cycle. Paper’s main work and conclusions are as follows:(1) First of all, this article describes the domestic and abroad researching status of wheel and rail profile optimization methods and summarizes rail grinding technology in detail. According to the research status quo, this article puts forward the researching idea, approach and technical route. It is going to clear up the significance of reducing the contact stress between wheel and track by implementing steel track profile optimization.(2)An optimum design of heavy-haul of railway’s rail profile which directly treats contact forces between wheel and rail as its optimization goal is established. Based on the wheel/rail contact geometry relationship, the finite element parametric model has been successfully established by using APDL parametric language and the maximum contact stress between wheel and rail located in rail profile’s different places are acquired too. This paper established the numerical algorithm of the rail profile’s optimization method. Based on the joint simulation of three-dimensional finite element contact stress analysis and the rail profile’s optimization algorithm, the numerical method of rail profile’s optimization design was established.(3) This article puts forward a rail profile’s adjustment method which is based on trigonometric function. The adjustment function is easy to control the depth and width of profile’s adjustment and can guarantee the profile’s function smoothly differentiable at the same time. On account of the achieved the maximum contact stress distribution, the calculation method of those optimizing parameters has been built such as point location, width, depth. At the same time, the optimal coefficient’s getter has been established. Discuss and analysis its influences on the contact stress distribution.(4) Using the established model and optimization method respectively to conduct the pre grinding of the heavy-haul railway standard rail and the corrective polishing the target profile of wear type 75kg/m. The results show that the optimized rail profile’s contact geometry and mechanics performance is obviously better than the former. The optimized steel tracks improve the contact status between wheel and track, significantly reducing the contact stress and prolong the service life of the rail. The results have some certain guidance on the target profile’s design and optimization of the rail grinding maintenance operations in railway.