The Study Of Elastohydrodynamic Lubrication Of Point Contact Based On Interfacial Adsorption

With the rapid development of the economy,China's high-speed railway construction is fast.Bearing is an important part of high speed train.Its lubrication is not only related to the loss of parts,but also to the safety of the train.At the same time,in view of the emission reduction and consumption reduction of energy and materials in industry,the scientific researchers put forward the concept of “lubrication economy”.Improving lubrication can not only reduce loss,but also ensure safety of railway working.It also helps to lubricate parts of spacecraft under vacuum environment,to lubricate parts in marine corrosive environment and to lubricate between artificial joints and cartilage.Elastohydrodynamic lubrication(EHL)is a common form of lubrication in mechanical parts.EHL oil film can not only withstand extreme conditions of high load and high shear force,but also make it possible to reduce friction.Elastohydrodynamic lubrication is one of the effective solutions.Therefore,the research of elastohydrodynamic lubrication will have a significant impact.Therefore,the elastohydrodynamic lubrication of point contact based on the interface adsorption is studied.The optical interference principle is applied to the experimental study on an improved point contact elastohydrodynamic lubrication optical test rig.According to the abnormal part of the friction coefficient curve,the high pressure pure sliding experiment of the glass plate and the steel ball with different surface energy is carried out.It is found that the decrease of the friction coefficient is related to the entrance depression Surface wettability not only affects the friction coefficient,but also affects the occurrence of interfacial slip.Through the analysis of the image of the oil film under different conditions,found that the larger the load is,the more prone to form entrance dimple.The results are as follows: under high load,the interface slip is easier to occur,and the entrance dimple is attributed to the non Newtonian fluid properties of the lubricating oil.In the course of experiment,observed the“tri-dimple”phenomenon by the interference image,exploratory study of this abnormal phenomenon.It is preliminarily concluded that the “tri-dimple”phenomenon is caused by the local formation of the adsorption layer,and the adsorption layer may be formed on the surface of the steel ball and the surface of the glass plate.Optical elastohydrodynamic lubrication experiments were conducted on two steel balls with different surface wettability.Optical elastohydrodynamic lubrication experiments were conducted on two steel balls with different surface wettability.The influence of the adsorption layer on the oil film shape and friction force was investigated by measuring the friction coefficient and observing the oil film shape and the oil film profile.It is proved that the “tri-dimple” phenomenon can be attributed to the local formation of the adsorption layer,and the formation of the oil film shape of the “tri-dimple” is explained by the local viscoelastic model.In order to verify the formation position of the adsorption layer,EGC steel ball was used for comparative experimental study.Conclusion: a certain degree of inhibition of adsorption layer slip occurs;the low surface energy of EGC makes the adsorption layer hard to adsorb on EGC surface,thereby increasing the degree of boundary slip and reducing friction;the adsorption layer is unstable at high speed and hard to adsorb on the interface;The formation of adsorption layer depends on the surface wettability;wettability is not only an important factor in boundary slip,but also one of the important factors for the formation of adsorbed layer.