Mechanism of Thin Film Lubrication

点击翻译按钮获取中文摘要

Mechanism and of thin film lubrication and shear characteristics of solidified lubrication film were studied.1.Shear properties of lubricant at low temperature : The shearing or sliding occurred within a thin shear layr in an oil and the oil behaved as a viscoelastic or elastoplastic material. Shear stress tau was expressed by tau=a exp (E/RT). Here, a, E,R,and T are an constant, activation energy, gas constant and absolute temperature, reapectively.2.Traction properties in concentrated contact : The coefficient of traction was mainly determined by alphap of a product alpha multiplied by p. alphap is a measure of the packing state of oils subjected to shearing.3.Limiting ability of oils to built up a hydrodynamic lubrication film : There is a critical sliding speed above which the oil film thickness inversely decreased in spite of increasing the sliding speed or the value of bearing modulus. The friction force also decreased with increasing the sliding speed above the critical one. Therse phenomena were mainly ascribed to that only the lower viscosity components of the supplied oil were prone to be introduced to the conjunction zone.4.Ultra thin film behavior in accelerating and decelerating motion : The oil film thickness in changing sliding speed tests was not equal to that in the corresponding constant sliding apeed. The difference in oil film thickness was brought mainly about squeeze action.