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本文提出了在实验室条件下轮轨关系的模拟技术及其限度。粘着系数,蠕滑,接触应力,塑流,磨耗及表面粗糙度均能在实验室进行模拟。尺寸效应在试验装置设计中占有重要地位。两种类型的实验室模拟、即赫兹模拟及几何模拟文中加以比较。IIT-GMEMD轮轨模拟试验装置也在文中加以讨论。计算了各种美国铁路货车与机车在两种模拟下的接触应力。探讨纵向粘着系数—蠕滑相互关系的试验在新接触表面及磨耗表面两种条件下进行。磨耗表面条件下进行的试验数据显示,在平均应力水平低于7031公斤/厘米~2时,上述关系与Kalker的理论相符合,当接触应力超出上述水平,则结果有所不同。试验结果还表明,改变垂直载荷得出的各条不同的粘着—蠕滑曲线都可归化为一条简单的无量纲曲线。如果实际接触面积能测量,则相应的表达式可以获得。在干燥清洁的接触表面条件下,垂直载荷及粘着值不变时,蠕滑与接触面积的乘积应是常数。表示不同冲角值(从0°到0.5°)条件下的纵向、横向与合成的粘着系数与蠕滑相互关系的一组试验曲线已获得。可以看出,随着冲角增大,通过曲线区段的纵向粘着系数会明显地下降。试验中还发现小冲角振幅的蛇行运动实际上能增加所能得到的最大粘着系数。这意味着从所需要的粘着水平角度看、车轮踏面锥度是较有利的。在轮轨间存在油、水污染时,粘着系数将大大降低,而在油污染情况下撒砂能将粘着提高到清洁干燥表面条件时的水平,但撒砂后再经受油污染,粘着最大值会降到0.15以下。
In this paper, the simulation technology of wheel / rail relationship and its limitation under laboratory conditions are proposed. Adhesion, creep, contact stress, plastic flow, wear and surface roughness can all be simulated in the laboratory. The size effect occupies an important position in the design of the test device. Two types of laboratory simulations, Hertzian and geometric simulations, are compared. IIT-GMEMD wheel and rail simulation test device is also discussed in the article. Calculate the contact stresses of various U.S. rail cars and locomotives under the two simulations. Experiments to investigate the longitudinal adhesion coefficient-creep-slip relationship were performed under both new contact and wear surfaces. The test data under the wear surface conditions show that the above relationship is consistent with Kalker’s theory at an average stress level of less than 7031 kg / cm ~ 2 and the result is different when the contact stress exceeds the above level. The experimental results also show that the different stick-slip curves obtained by changing the vertical load can all be transformed into a simple dimensionless curve. If the actual contact area can be measured, the corresponding expression can be obtained. Under dry and clean contact surface conditions, the product of creep slip and contact area should be constant for a constant vertical load and adhesion value. A set of experimental curves representing the relationship between longitudinal, transverse and synthetic adhesion coefficients and creep under different angles of attack (from 0 ° to 0.5 °) has been obtained. It can be seen that as the angle of attack increases, the longitudinal coefficient of adhesion through the curve segment decreases significantly. It was also found in the experiment that meandering amplitude with a small angle of attack actually increased the maximum adhesion coefficient that could be obtained. This means that the wheel tread taper is more advantageous from the point of view of the required level of adhesion. In the presence of oil and water between the wheel and rail, the adhesion coefficient will be greatly reduced, while in the case of oil pollution, the sand can increase the adhesion to the level of clean and dry surface conditions, but after sanding the sand and then subjected to oil pollution, maximum adhesion Will fall below 0.15.