Experimental Invetigation Of The EHL Oil Film With Different Velocity Directions

In this thesis,the impact of different velocity directions of two surfaces on point contact elastohydrodynamic lubrication(EHL)film shape was investigated experimentally and theoretically.The work comprises following three parts: experimental study on effect of different velocity directions under orthogonal entrainment and sliding speeds,the effect of non-orthogonal entrainment and sliding speeds on EHL,the isothermal point contact analysis of orthogonal entrainment and sliding speeds.In the present thesis,a ball-on-disk testing rig was used to capture optical interference images and the experimental images were processed with a multi-beam intensity-based(MBI)lubricating film measuring technique to reconstruct the film shape.The angle between the speed of the steel ball and the glass disk is determined by the position of the servo motor on the arc guide rail.The steel ball and the glass disk were driven by two servo motors which were controlled by PLC program.The study of the different velocity directions under orthogonal entrainment and sliding speeds shows that the angle between the velocity of the steel ball and the glass disc,which is changed from 0° to 150°,will affect the film shape.The effects of different entrainment speeds,loads and lubricants on the shape and thickness of EHL film are considered.The wedge-shaped oil film occurs when surface velocities are different.The influence of non-orthogonal entrainment and sliding speeds on dimple is studied.The oil film thickness and shape were analyzed with different slid-roll ratio and the entrainment velocity under sliding speed was gradually perpendicular to the entrainment speed.The speeds of glass disc and the ball presents two conditions,the existence of large dimple occurs in the situation,where glass disk speed is greater than the ball speed.Increasing the slid-roll ratio and the entrainemnt speed result in the expansion of the dimple.Finally,the numerical analysis of the isothermal point contact with orthogonal entrainment and sliding speeds was carried out,and the numerical results are compared with the experimental results.