Measurement Of Boundary Slippage In EHL And Its Influence On Lubrication Films Under Reciprocating Motions

In this project, quantitative measurement of boundary slippage in EHL has beenachieved, and the responses of EHL films with boundary slippage were tested underreciprocating motions.The motor control system has been updated of a classical EHL optical test rig.Programs were designed (VisualBasic environments) for the motion control card toachieve micro-scale reciprocating motions with high accuracy. Moreover, controlprograms were also developed for step motions and multi-segment motion to satisfy thedemands of other tasks.A theoretical solver was developed to get the pressure of an initial impact dimplefilm for the entrainment motion measurement. An elastic deformation matrix and themeasured film thickness were used to obtain the film pressure by iterative numericalschemes. This calculation approach can be used to evaluate the influence of pressureson the boundary slippage.The wall slippage in an elastohydrodynamic contact zone has been quantified bymeans of tracking the movement of the impact dimple film core. Studies have beencarried out to reveal influencing factors on the slippage length, including the pressure,the initial simple depth and the entrainment velocity.Measurements have also been carried out to study the transient response of EHLfilms under reciprocating motion with boundary slippage, and the influences of loads,motion amplitudes, frequencies and interface adhesions. Especially, when an oil/SiO2interface was adopted with a kind of micro-reciprocating motion, there appeared anobvious amplitude attenuation of the dimple core reciprocating motion, and phasedelay, which can be attributed to the boundary slippage at the steel surface.