轨底坡对轮轨滚动接触行为的影响

EFFECT OF RAIL CANT ON WHEEL/RAIL ROLLING CONTACT BEHAVIOR

为了探讨轨底坡与轮轨滚动接触行为的内在联系,针对高速客运专线轮轨接触状况,即轮对踏面为LMA和钢轨为国产CN60,利用改进的三维接触几何程序、Kalker的三维弹性体非赫兹滚动接触理论及其CONTACT数值程序,分析比较轨底坡对轮轨接触几何参数、接触斑形状、接触斑滑动量、摩擦功、接触应力等的影响。通过分析计算可得,轨底坡对轮轨滚动接触行为有很大影响。尤其当轮对相对轨道横移在6mm～9mm范围内变化时,随着轨底坡从1/20到1/40的逐渐减小,轮对左右轮滚动半径差和等效锥度增大,这说明在1/40轨底坡下,轮对恢复对中的能力更好,更有利于曲线通过。1/40轨底坡对应的最大正压力、等效应力等较小,其对应的摩擦功较大。1/20轨底坡的情况刚好相反。综合考虑各种因素,对于LMA-CN60轮轨接触副,1/40轨底坡较1/20轨底坡的接触状态更好。数值结果为轨底坡的设计提供重要的参考依据。

In order to study the relation between rail cant and wheel/rail rolling contact behavior, it is analyzed that LMA wheelset with 1353 mm back-to-back distance in contact with a tangent track with 60 kg/m rails and 1435 mm gauge. The improved program of three-dimensional contact geometry of wheelset/track is used to calculate the contact geometry parameters of the wheelset/track versus the lateral displacement of the wheelset. These analyzed parameters include the contact point location, the contact angle, the instant rolling circle radius, the equivalent conicity, and the normal distance between the wheel and rail. They are used in the calculation of the creepages and the rolling contact behavior of the wheelset. The creepages are calculated with formulas and the rolling contact behavior is determined by using Kalker＇ s theory of three-dimensional elastic bodies in rolling contact with non-Hertzian and the corresponding program CONTACT. The calculated rolling contact behavior comprises the contact area, the stick/slip areas in the contact area, the slips, the contact stresses, and the friction work. The effect of the different rail cants on the contact geometry parameters and the mUing contact behavior is also investigated. The results obtained show that the rail cant has a great influence on the wheel-rail rolling contact behavior. The rolling radius difference and the equivalent conicity increase with the rail cant decreasing from 1/20 to 1/40, especially when the lateral displacement of the wheelset ranges from 6 mm to 9 mm. This character indicates that the rail cant of 1/40 more easily strengthens the self-centring capability of the wheelset and is propitious to curving negotiation. The maximum pressure and equivalent stress for 1/40 rail cant case are the smallest, but the total friction work is the greatest. The corresponding results for 1/20 rail cant show the opposite situation. According to all the numerical results, it is found that 1/40 rail cant is better than 1/20 for LMA-CN60. The results are useful for the optimum design of the rail cant.