Size Effect on the Behavior of Thermal Elastohydrodynamic Lubrication of Roller Pairs

Abstract

In order to investigate the size effect on elastohydrodynamic lubrication (EHL) of roller pairs, complete numerical solutions for both the Newtonian fluid and the Eyring fluid thermal EHL problems of roller pairs under steady state conditions have been achieved. It can be seen that there is no size effect on the isothermal EHL performance; however, there is a very strong size effect on the thermal EHL performance. Results show that the term of shearing heat is the most important factor for the film temperature when the size of a contact changes. Comparison between the Newtonian solution and the Eyring solution has been made under some operating conditions. It is interesting to see that the effective viscosity of the Eyring fluid is nearly the same as that of the Newtonian fluid when the size of a contact is large enough. The non-Newtonian effect, therefore, can be ignored when the size of a contact is very large. It is equally interesting to see that the thermal effect can be ignored when the size of a contact is very small. In addition, the influence of the velocity parameter, the load parameter, and the slide-roll ratio on the lubricating performance for various sizes of contacts has been investigated.

A thermal EHL investigation for size effect of finite line contact on bush-pin hinge pairs in industrial chains

“…The non-Newtonian fluid, thermal effect and oil starvation effect were considered comprehensively. Liu et al (2012) studied size effect on the behavior of thermal EHL of roller pairs. But unlike rolling element bearings, the equivalent curvature radius of the contact area of sleeve-pin hinge pair, which increases with the increase of chain number, can be quite large.…”

Numerical study on the interaction of transversely oriented ridges in thermal elastohydrodynamic lubrication point contacts using the Eyring shear-thinning model

“…However, the solutions presented in this section is for a relatively small contact (R ¼ 0.02 m), in such a case the change of _ across the film is not large, so that m is mainly determined by the effective viscosity. More results will be given in the next section for different values of R, so that to see if the size effect reported in Liu et al 14 and Kaneta et al 15 still exist under transient conditions for point contacts with rough surfaces.…”

“…Kudish et al 11 and Krupka et al 12 have described that the classical isothermal Newtonian EHL film thickness formula 13 overestimate the film thickness for the real machine elements if the element scale is small and the lubricant is sheared thinning within the inlet zone. Liu et al 14 have pointed through thermal line contact EHL analysis that for a very small contact the thermal effect is negligible but the shear-thinning property of the lubricant must be considered, whereas for a very large contact the thermal effect controls the film performance and the shear-thinning effect can be neglected. Furthermore, Liu et al 14 and Kaneta et al 15 have shown that the dimensionless film thickness and the friction coefficient decrease as the contact size increases.…”

“…Liu et al 14 have pointed through thermal line contact EHL analysis that for a very small contact the thermal effect is negligible but the shear-thinning property of the lubricant must be considered, whereas for a very large contact the thermal effect controls the film performance and the shear-thinning effect can be neglected. Furthermore, Liu et al 14 and Kaneta et al 15 have shown that the dimensionless film thickness and the friction coefficient decrease as the contact size increases.…”

A thermal EHL investigation on plate-pin hinge pairs in silent chains using a narrow finite line contact

“…Han et al (2017) performed an experimental investigation on the finite line EHL contact under variable velocity condition. Liu et al (2012) studied size effect on the behavior of thermal EHL of roller pairs. Liu et al (2019) established a thermal EHL model for crowned rollers and studied the effects of sliding-rolling ratio, load, crown radius and roller length on the lubrication state and temperature rise of in the contacts.…”