A Theoretical and Experimental Study of EHL Lubricated With Grease

Abstract

It is known that the apparent viscosity of grease varies with service time and that grease starvation is important in EHL. However, these effects were often ignored in the research of EHL lubricated with grease. This paper deals with the thixotropy of grease and determines which value of rheological parameters can be used in numerical analysis. The starved boundary position and its cause are also discussed and observed experimentally. A steady starved boundary of grease was adopted in computing the film shape. Since in both calculation and experiment the thixororpy and grease starvation were considered, the numerical solution was quite consistent with the experimental data. This paper explains why even though the apparent viscosity of grease is always larger than that of its base oil, the film thickness of EHL lubricated with grease is equal to or lower than that with the oil alone.