Friction model of elastic-plastic line contact in mixed lubrication regime with non-Newtonian lubricant

Abstract

The friction characteristics of the lubricated rough surfaces are of great significance for the lubrication design of mechanical structures. To study the behaviour of friction coefficient in the rolling-sliding coexisting line contact rough surfaces under mixed lubrication regime, the Kogut-Etsion elastic-plastic model and the Carreau rheological model are utilized to describe the dry rough contact and the non-Newtonian characteristics of the lubricant film, respectively. A mixed lubrication model for predicting friction coefficient is proposed based on the load-sharing concept at which the normal load is shared by the lubricant film and the asperity component. The effects of normal load, surface roughness and lubricant inlet viscosity on hydrodynamic scaling factor, film thickness parameter and the coefficient of friction were analyzed. The dimensionless predictive expression for the critical sliding velocity is derived by nonlinear regression. The research results provide theoretical guidance for the lubrication design and optimization of mechanical structures.

Machine learning approach for the prediction of mixed lubrication parameters for different surface topographies of non-conformal rough contacts

“…Table 3 represents the parameters, namely, rolling speed ( U r ), skewness ( S sk ), kurtosis ( S ku ), material hardness ( H ) and pattern ratio ( γ ) and their minimum (min) to maximum (max) range, which are used as the input features in the MLP model. It should be noted that the min-to-max range of parameters as shown in Table 3 has been considered previously for the friction and wear analysis of non-conformal contacts (Ling et al , 2022; Taylor and Sherrington, 2022). It should also be noted that the contact load ( p max = 1.75 GPa) and RMS roughness ( S q = 0.3 µm) are kept constant during the generation of the input data set.…”

A numerical study on the impact of lubricant rheology and surface topography on heavily loaded non-conformal contacts

“…research showed that the shear thinning behavior (pseudo plastic) of many lubricants (especially polymer-based lubricants) can be accurately characterized using the Carreau model [39,40]. So, in this work, the non-Newtonian characteristics of the lubricant are modelled by employing the Carreau equation [40]. The relationship between generalized viscosity η e of lubricant and shear strain rate (  g) is given in equation ( 9).…”

“…This strongly indicates that the surface roughness effect cannot be overlooked in elastohydrodynamic analysis of non-conformal contacts. Recently, Li et al [40] developed a line contact mixed-EHL model for predicting the traction coefficient considering non-Newtonian rheology of lubricant. They also showed the effect of surface roughness, speed, and lubricant viscosity on traction behavior.…”