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An Analytical Approach for Analysis of Slider Bearings with Non-Newtonian Lubricants

DOI: 10.1155/2014/404759

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Abstract:

In this study, a regular perturbation technique is utilized to derive the modified Reynolds equation which is applicable to power-law lubricant. The performance of slider bearings including pressure distributions, velocity distributions, film thickness, load capacity, flow rate, shear force, and friction coefficient is also derived analytically for various , flow indices ( ), and outlet film thicknesses ( ). These analytical solutions are clear to find the effects of the operation parameters rather than numerical methods. It can be simply and fast used for engineers. Subsequently, these proposed analytical solutions are used to analyze the lubrication performance of slider bearing with the power-law fluids. 1. Introduction In all geometric-shaped sliders, wedge sliders provide the simplest support for fluid lubrication, and thus they are usually used as components of thrust slider bearings. With the development of modern machines, polymer oil, especially engine oil for vehicles such as multigrade crank case oil, is usually added to the lubricating oil in order to effectively reduce the friction loss of machine parts. However, such lubricants containing polymer belong to the non-Newtonian fluid type. As a result, the non-Newtonian characteristics of lubricants have become important. In recent years, there have been a great number of models used to describe non-Newtonian fluids. Among them, the power-law model is the simplest and most widely used. Safar and Shawki [1] divided fluids into three different categories: Newtonian fluid, , which is assumed as the type of ordinary pure fluid and gas; dilatant fluids or shear-thickening fluids, , which exhibit an increase in apparent viscosity with increasing shear rate; pseudoplastic fluids, , which are characterized by linearity at extremely low and extremely high shear rates. With regard to investigating slider bearings, many scholars [2–4] have derived closed-form solutions of Newtonian fluid for different slider bearings shapes. Hamrock [5] analyzed pressure distributions, velocity distributions, maximum pressure, film thickness, load capacity per unit width, flow rate, and friction coefficient of fixed-incline slider bearings with Newtonian fluid. As mentioned above, the closed-form solutions focus on simple geometry shape and Newtonian fluid. However, many experiments have shown that base oil blended with long-chain additives to a Newtonian fluid gives the most preferable lubricant results and can improve the load-carrying capacity and reduce the friction parameter [6, 7]. Therefore, the use of

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