RECONSTRUCTION OF ELASTOHYDRODYNAMICLUBRICATION THEORY

在用光学干涉技术直接观测滚动/滑动条件下点接触弹流润滑(EHL)膜的基础上，提出了一个新的EHL理论，该理论应考虑接触表面弹性模数的差异、平行于切向接触面的表面压力分量以及润滑油的凝固现象。其他主要结果如下：(1)流体流动以剪切流为主，几乎没有压力诱导流动。(2)局部油膜以表面平均速度流动，而形状和厚度保持不变。(3)在凹槽或凹槽的上游和下游，滑滚比分别为正值和负值时，局部油膜厚度发生局部减薄。局部胶片缩减面积随着滑转…值的增加而增加(4)折合油膜厚度恢复到光滑状态。表面值是流体从入口进入弹流体区，沿滑动方向流经凹槽或凹槽进入油膜还原区域。(5)如果凹槽的波长大于|Sigma|，则凹槽产生的减薄油膜厚度不会发生干涉，其中a是赫兹接触半径，Sigma是滑滚比。(6)在较高的往复运动频率和较短的行程长度条件下，抑制了稳定的弹流润滑油膜的形成。这是因为前一次冲程中产生的气泡导致了下一次反向冲程中的油荒。(7)当弹性模量值较低的物体的表面速度快于弹性模量值较高的物体的表面速度时，当前者的曲率半径大于后者的曲率半径时，在接触区产生深圆锥形凹陷(凹陷)。酒窝的行为像固体而不是液体，形成过程由内部条件决定，而不是入口条件。较少

On the basis of direct observations of point contact elastohydrodynamic lubrication (EHL) films under rolling/sliding conditions using the optical interferometric technique, it has been asserted that a new EHL theory should be constructed by taking into account the effects of differences in elastic moduli of the contacting surfaces, surface pressure components parallel to the tangent contact plane, and the solidification phenomenon of lubricating oils. The other main results are summarized as follows :(1)In the EHL conjunction shear flow dominates the fluid flow and pressure induced flow is almost absent.(2)As a result, a local oil film flows approximately at the average speed of the surfaces while holding the shape and thickness.(3)A local reduction in film thickness occurs at a certain area downstream and upstream of a groove or a dent according to a positive and negative values of slide-to-roll ratio, respectively. The local film reduction area increases as the value of slide-to-rol … More l ratio.(4)The recovery of the reduced film thickness to the smooth.surface value is attained by fluid entering the EHL area from the inlet and the flowing into the film reduction area across the groove or the dent in the direction of sliding.(5)If the wavelength of grooves is more than a|SIGMA|, reduced film thicknesses produced by the grooves never interfere, where a is the Hertzian contact radius and SIGMA is the slide-to-roll ratio.(6)Under conditions of a higher frequency of reciprocation and a shorter stroke length, the formation of a stable EHL film is inhibited. This is because air bubbles produced in the preceding stroke result in the oil starvation in the succeeding reverse stroke.(7)When the surface velocity of the body having a lower elastic modulus is faster than that of the body having a higher elastic modulus and when the radius of curvature of the former is larger than that of the latter, a deep conical depression (dimple) is produced in the contact area. The dimple behaves like a solid rather than a liquid, and the formation is dominated by the inside rather than inlet conditions. Less