变摩擦条件下高速钢轨焊缝处轮轨滚动接触-冲击行为研究

Study on Wheel⁃Rail Rolling Contact⁃Impact Behavior at High⁃speed Rail Welds under Variable Friction Conditions

采用变摩擦系数能够较为准确地刻画轮轨滚动接触行为。为研究变摩擦系数对钢轨焊缝处轮轨滚动接触行为的影响,建立三种不同钢轨焊缝工况的三维轮轨瞬态滚动接触有限元模型,通过对比库伦型摩擦系数的结果,计算分析变摩擦系数对轮轨力、接触斑内的微滑以及黏滑分布等接触行为的影响。结果表明:变摩擦系数接触斑内的滑动区域占比会更大且在滑动区域会引起黏滑振荡现象,当轮轨界面滑动现象越明显时,黏滑振荡越剧烈;变摩擦系数对法向接触解的影响不大,切向接触解会因接触状态的改变显著受到影响,造成凸形1焊缝的不均匀磨耗;变摩擦系数会影响von Mises应力分布,其最大von Mises应力发生的位置会向轨底移动,对伤损出现的位置产生影响。

The wheel-rail rolling contact behavior can be described more accurately by using variable friction coefficient.In order to study the effect of variable friction coefficient on wheel-rail rolling contact behavior at rail weld,a three-di-mensional wheel-rail transient rolling contact finite element model was established for three different rail weld conditions.By comparing the results of Coulomb friction coefficients,the effects of variable friction coefficients on wheel-rail forces,micro slip within contact area and stick-slip distribution were calculated and analyzed.The results show that the propor-tion of the sliding area in the contact area with variable friction coefficient will be larger and the stick-slip oscillation will be caused in the sliding area.The more obvious the sliding phenomenon at the wheel-rail interface is,the more severe the stick-slip oscillation will be.The variable friction coefficient has minor effect on the normal contact solution,while the tangential contact solution is significantly affected by the change of contact state,resulting in uneven wear of convex 1 weld.The variable friction coefficient will affect the von Mises stress distribution,with the location of the maximum von Mises stress moving towards the bottom of the rail,affecting the location of the damage.