A Basic Study on Thermo-Elasto-Plastic Mixed Hydrodynamic Lubrication Problems

用微型ITV摄像机透过玻璃球观察了弹性承窝与承受正弦载荷的弹性球之间的润滑情况。在减载阶段，观察到接触区域周围产生空化区。实验中测得了空腔内的负压，随着时间的推移，空腔面积的增大，负压降低。表面之间的曲率差异在决定润滑方式方面起着重要作用。如果一致性低，则在短时间内发生高度集中的接触。另一方面，如果两个表面高度一致，则流体保持在两个表面之间，并且在宽的区域上产生相当高的流体压力，然后，在中心处保持低的接触压力。然而，最大接触压力不是发生在中心，而是发生在靠近外侧边缘。从上述结果来看，必须仔细选择一致性以减少磨损，并且重要的是选择边缘附近的两个表面的形状以减少接触压力和它们的磨损。本文提出了一种新的弹性润滑理论，并与实验结果进行了比较，两者吻合较好。当轴承数量增加时，发生了从混合润滑到流体润滑的过渡，摩擦系数显著降低到0.01。建立了两粗糙表面接触的理论模型，并考虑了销轴形状的热变形。发现两个平行表面之间摩擦力如此小的原因是由于加热引起的销形状的变化。

The lubrication condition between an elastic socket and a glas sphere subjected to a sinusoidal load was observed by a miniature ITV camera through the glass sphere. Generation of a cavitation zone around the contact area were observed in the load reducing phase. A high subambient pressure was measured in the cavity and it was reduced when the area of cavity increased with the progress of the time. The difference of the curvature between the surfaces plays an important roll in deciding the mode of lubrication. If the conformity is low, highly concentrated contact occurs over a short period of time. On the other hand, if the both surfaces are highly conformed, the fluid is kept between two surfaces and considerably high fluid pressure is generated over a wide area and then, the contact pressure is kept low at the center. However, the maximum contact pressure occurs not in the center but near the outside edge. Judging from the above results, the conformity must be selected carefully to reduce wear and it is important to chose the shape of two surfaces near the edge to reduce contact pressure and their wear. A new elasto-sixed lubrication theory was developed and the results were compared with those from the experiments and both agreed well.Mixed lubrication between two parallel surfaces were also investigated using a pin and disc. When the bearing number increased, transition from mixed lubrication to fluid lubrication occurred and the friction coefficient was reduced significantly to 0.01. A theoretical model was developed for the contact between two rough surfaces and also the thermal distortion of the shape of the pin was also considered. The reason to show such a small friction between two parallel surfaces was found to be the change of the shape of the pin due to heating.