Mixed EHL Problems: An Efficient Solution to the Fluid–Solid Coupling Problem with Consideration of Elastic Deformation and Cavitation

Abstract

For transient mixed Elastohydrodynamic lubrication (EHL) problems, a novel solution is required to predict friction loss and wear in sliding or rolling parts. However, existing solutions have numerous limitations. In general, the lower the oil film thickness is, the more serious the non-linear problem is. This paper presents an efficient solution to tackle the non-linearity of the mixed EHL problem. The elastic deformation in the fluid–solid iteration coupling problem is divided into two parts: One is induced by the hydrodynamic pressure. This part of the deformation is obtained by the unsteady EHL-FBNS (Fischer–Burmeister–Newton–Schur) solver by considering both mass-conserving cavitation and elastic deformation. The other part of the deformation is introduced by the asperity contact pressure. It can be obtained by the Newton–Raphson method. After some limited iterations, the mixed EHL problems can be solved by evaluating the residual total pressure (including hydrodynamic pressure and asperity contact pressure). The proposed methodology was validated against the results from the published literature and applied to characterize the tribological performance of point contact with moving texturing. It appears that the developed method can be effectively used for tracking the tribological behavior of friction pairs.

The Influence of Non-Gaussian Roughness and Spectral Properties on Mixed Lubrication for Heavily Loaded Counterformal Contacts

“…Zhang et al [25] employed a PC average flow model for their mixed lubrication analysis and concluded that low roughness, larger asperity radius, and transverse roughness lay exhibit a lower coefficient of friction. Gu et al [18] employed a PC average flow model to study the transient mixed lubrication problem, and a good match was found with published experimental results (smooth surface with moving texture and rough surface with moving texture). Leighton et al [26] developed formulas for calculating flow factors (pressure, shear, and shear stress) for cross-hatched rough surfaces.…”

“…To calculate the asperity contact pressure, various statistical and deterministic elastic and elastic-plastic contact models have been used [14][15][16][17]. Due to its easy implementation and fast computational ability, the average flow model based on PC (Patir and Cheng) flow factors has extensively been used for mixed lubrication analysis of conformal and counterformal contacts [18,19]. Despite having many advantages, average flow-based mixed lubrication models also have some limitations.…”

“…The asperity contact pressure is integrated into the film thickness equation, and along with Reynolds and load balance equations, the true solution is obtained by employing an EHL-FBNS solver, which is also extended in this work, according to Ref. [18] for mixed lubrication analysis. A detailed investigation is conducted to study the effect of various surface features on the lubrication performance of heavily loaded counterformal contacts.…”

Research on the Optimal Design Approach of the Surface Texture for Journal Bearings

“…Meanwhile, the effect of the surface roughness on the lubrication performance can be realized by introducing the flow factor defined by Patir and Cheng [16] into the JFO model. The corresponding equation can be expressed as follows [17][18][19]:…”

Numerical simulation of the dynamic fluid–solid coupling in journal bearing with the effect of surface topography in consideration

“…The detailed steps of the FBNS algorithm have been found in the work of Woloszynski et al 34 Interested readers can refer to these related works. 20,34,35 As shown in Figure 6, a GR (coarse to fine) strategy can be employed to obtain a further improvement in the convergence speed. In the GR strategy, the initial values in the high-layer grid are from the solutions of p and θ in the low-layer grid.…”