第三介质对轮轨最大静摩擦因数影响的试验

Experimental Study on the Influence of the Third Medium on the Wheel/rail Maximum Static Friction Coefficient

轮轨摩擦因数的变化影响列车运行时的轮轨黏着特性,轮轨间的最大静摩擦因数可以界定轮轨接触区的黏着状态,轮轨黏着对于机车实现牵引制动具有重要意义。针对水、油、砂等'第三介质'对轮轨最大静摩擦因数的影响,搭建轮轨接触试验台进行轮轨接触试验与轮轨摩擦接触试验。对试验结果对比分析表明轮轨接触试验的轮轨接触斑与有限元仿真的接触斑形状及面积相同。与干燥清洁状态下的轮轨最大静摩擦因数相比,当轮轨间单独存在水或油介质时会降低该系数值,且单独存在油介质时该系数值最小;当轮轨间同时存在水、砂介质时,该系数值增大;当油、砂同时存在时,最大静摩擦因数略大于油介质工况,但依旧小于干燥工况下的系数值。撒砂可以增加轮轨最大静摩擦因数,河砂具有更好的增黏效果但会对轮轨表面造成更严重擦伤,建议使用石英砂作为轮轨增黏介质。

The wheel/rail adhesion has great significance for the locomotive to achieve traction and braking, while the Wheel/rail friction coefficient would affect the wheel/rail adhesion characteristics and the wheel/rail maximum static friction coefficient could be used to define adhesion state of the wheel/rail contact area. In order to study the influence of 'third medium' on the wheel/rail maximum static friction coefficient, a wheel/rail contact test-rig is set up to carry out the experimental study, such as wheel/rail contact test and wheel/rail maximum static friction coefficient test. Though the comparative analysis of the test results, the conclusions are drawn. The shape and area of wheel/rail contact spot obtained by the wheel/rail contact test is consistent with that by the finite element simulation. Compared with the wheel-rail friction coefficient in dry and clean condition, the wheel/rail maximum static friction coefficient reduces when water or oil medium exists between the wheel and rail alone. And the value of the coefficient under oil condition is the smallest. Besides, it increases when there is water and sand between wheel and rail. The coefficient under the condition of oil and sand between wheel and rail is larger than that under the condition of oil alone, but it still less than that under the drying conditions. Sanding could increase the wheel/rail maximum static friction coefficient, and river sand has better adhesive effect than the quartz sand, while resulting in more serious scratch on the wheel/rail surface. Therefore it is recommended to use quartz sand as wheel/rail increasing-viscosity medium.