Optimization Design Of Heavy-Haul Wheel Profile Basing On Improving Wheel-Rail Contact Status

With the increase of heavy haul freight volume year by year in our country, improving the train speed and axle load becomes an effective way to develop railway transportation, which is also the development direction of China’s rail freight transportation. However, the increase of the train load and the marshalling length will aggravate the interaction force between wheel and rail which leads to vehicles and track equipments damage, reduction of traffic safety and intensified wear between wheel and rail, etc. which are an urgent problem to deal with during the process of then heavy haul transport development. Wheel/rail contact geometry relationship is one of the bases of wheel/rail dynamics and profile research. A good rail and wheel tread profile matching contact can effectively reduce the wear and prolong the service life of wheel and rail. In order to obtain a good dynamic performance, improve the contact status and wheel/rail force, it is necessary to optimize the heavy haul wheel profile according to existing lines.Nowadays, the heavy railway mainly uses rails of two specifications, namely60kg/m and75kg/m. The contact between two rails of60kg/m and75kg/m with LM tread will produce different static contact and dynamic performances. In order to analysis the performance of LM tread with two rails, find out the emphasis of optimization, this article established the static wheel/rail contact model and the vehicle dynamics model. The results showed that the LM tread contacted with60kg/m rail had better geometric properties and static contact mechanics properties. At different orbital parameters, the wheel with60kg/m rail had a better curve performance, and had lower crack damage value and wear damage value in high and low earth orbits. Therefore, for the75kg/m rail, better matching wheel profiles should be optimized.Rolling radius difference is one of the main parameters of the dynamic performance of the vehicle set which is closely related with and determines the dynamic performance. This article derives the wheel/rail contact geometry relationship in detail, gets the relation of wheel/rail contact point head offset function, rolling radius difference and the wheel/rail surface, puts forward a new method to solve the wheel tread reversely according to the rolling radius difference. Rolling radius difference is selected as the optimization objective function. The wheel/rail contact point head offset function is adjusted to ensure the target of rolling radius difference function. Directly solving constrained optimization algorithm of complex method is used as the optimization method, improving the wheel/rail contact state as the optimization target, to obtain the rolling radius difference curve that the new designed wheel profile with the given target rail, and the corresponding program of Matlab is developed.The75kg/m rail is solved reversely to get the heavy haul wheel profile which meets the target of rolling radius difference function. The optimization results show that, the wheel tread after the optimization can significantly reduce the wheel/rail contact stress, improves the distribution of wheel/rail contact point, more reasonable distribution, has a better contact performance of wheel/rail and curve negotiation performance, namely crack damage value and wear damage value of the wheel/rail are reduced effectively.