An Average Flow Model Considering Non-Newtonian Characteristics With Application to Grease Behavior

The influence of the grease-water two-phase emulsion on the bearing track on the film formation has been studied by carrying out optical interferometry experiments on a ball disk test rig to observe the dynamic film-forming behavior of lubricating grease under steady-state and micro-oscillation conditions. It is found that free water cause a brief rise in the grease film under steady-state conditions, specifically due to the grease-water phase connecting the oil band on both sides of the oil reservoir. The experiment determines that the state of the phase before entering the elastohydrodynamic lubrication (EHL) contact is water-in-oil. For the reciprocating motion and oscillation, the effects of the amount of free water and the length of the motion stroke are discussed in detail. It is found that for reciprocating movements with long stroke lengths, the effect of free water is summarized to enhance the fluidity of the fibrous mass of the grease thickener in the first few cycles of the movement. For shorter stroke lengths, the effect of free water is a scouring effect on the contact zone grease after 100 cycles. This paper provides new insights into the effects that causes water pollution to the point contact lubrication during the transformation from reciprocating motion to fretting.

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Effect of Grease Composition on Impact-Sliding Wear

Wang,

Lv,

Han

et al. 2024

Lubricants

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Impact-sliding experiments were performed by using four self-made lithium-based greases, namely Yangtze Grease 1, Yangtze Grease 2, Yangtze Grease 3, and Yangtze Grease 4. The influence of base oil viscosity, thickener content, and morphology of thickener fiber clusters on the lubricating state were visually explored, combined with field-emission microscopy and two-light interference technology. The grease film distribution at the middle section was measured using Dichromatic Interference Intensity Modulation (DIIM) software. All experiments were executed in a completely flooded environment. The results show that among the components of grease, the base oil’s viscosity has the greatest impact on the anti-wear performance of the grease. As the viscosity of the base oil increases, the grease exhibits better anti-wear performance. The grease film thickness under the condition of high-viscosity base oil is about 10 times higher than that under the condition of low-viscosity base oil. Secondly, the content of thickener in the grease needs to be controlled within a reasonable range. The experiments indicate that the effect of thickener content on the grease’s film-forming properties becomes more pronounced at higher speeds. From the experiment using YG 4, it can be seen that a higher thickener content under high-speed conditions increases the thickness of the lubricating grease film by about 10 times. The dimensions of the thickener fibers and the density of their entanglement structure significantly influence the rheological properties and load-bearing capacity of the grease. Larger fiber sizes and higher entanglement densities result in reduced grease fluidity and recovery but enhance its load-bearing capabilities. In order to obtain the best anti-wear performance during impact-sliding motion, the size of the thickener fiber and the density of the entanglement structure need to be controlled within an appropriate range.

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An Average Flow Model Considering Non-Newtonian Characteristics With Application to Grease Behavior

Cited by 3 publications

References 39 publications

A Mixed EHL Analysis Method for Grease and Formulas for Film Thickness and Asperity Load

A Mixed EHL Analysis Method for Grease and Formulas for Film Thickness and Asperity Load

Influence of Free Water Droplets on Film Formation Under Point Contact Grease Lubrication

Effect of Grease Composition on Impact-Sliding Wear

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