# Study on Lubrication Performance of Journal Bearing with Multiple Texture Distributions
## 1 Introduction  
Surface texture refers to the micro-concave/convex morphology. An appropriate surface texture can effectively reduce the wear of the friction pair and improve the load capacity of the oil film [1; 2; 3; 4]. [PERSON] et al. [5] proposed a liquid lubrication theory applicable to parallel surfaces and explained the lubrication mechanism based on surface micro-irregularities. This theory is in reasonable qualitative agreement with experimental results. Since then, the usage of the texture of technology to improve lubrication performance has aroused great interest among researchers. [PERSON] [6] found that micro-dimples on the friction surface were able to significantly improve the load capacity, the wear resistance and the friction coefficient compared with the non-textured components. This beneficial effect was verified experimentally using the Laser Surface Texturing (LST) technique. The effects of different texture shapes and distributions on the lubrication characteristics of bearing have also been investigated. [PERSON] [7] studied the effect of the dimple distribution and position on the dynamic lubrication characteristics of bearings using the computational fluid dynamics (CFD) method. It was found that the optimal distribution of dimples on the bearing surface depends on the operating conditions. When the eccentricity changes, the optimal location of the deep dimple changes accordingly. [PERSON] [8] studied the effect of distribution and size of spherical texture on the load capacity of a sliding bearing. The optimum parameters of the dimples and the favorable LST mode for achieving maximum load capacity were found. [PERSON] et al. [9] studied the hydrodynamiceffect of a few deterministic texture shapes of a journal bearing, and found that the parallelepiped texture shows advantages in enhancing the bearing performance compared with other geometries. Based on the Reynolds equation, [PERSON] et al. [10] used the genetic algorithm to study the effect of the cross-section shape of concave/convex textures on the lubrication performance of an infinitely wide journal bearing. The results showed that the convex texture was better than the concave texture at minimizing the friction factor and simultaneously maximizing the bearing capacity. Increasing attention has been given to partial textures, which is an effective approach to improving bearing performance. [PERSON] et al. [11] presented a partial texture that was able to significantly increase the load capacity. [PERSON] et al. [12] developed a theoretical model of a partially textured slip slider and coupled stress fluid lubricated journal bearing. It was found that the partially textured slip was able to effectively improve the load capacity and reduce the friction coefficient. From this literature review, it can be concluded that the concave/convex surface texture has attracted a lot of attention in the last two decades, and can serve as a micro hydrodynamic bearing to provide additional load capacity. The effects of texture shape, texture size, and texture distribution on load capacity have been systematically studied. Thus, the concave/convex surface texture seems to be a good candidate to improve the load capacity of bearing. However, apart from that, the friction coefficient is another important factor affecting the lubrication performance of bearing. However, the effect of concave or convex textures on the friction coefficient is not very significant, and is sometimes not even beneficial [13; 14]. In 2011, [PERSON] [13] conducted numerous experiments to investigate the performances of plain and micro-grooved journal bearings, in which the micro-grooves were made by cutting micro-channels around and across the journal bearing surfaces. The results showed that the friction coefficients of the journal bearings with micro-grooved textures were higher than those without texture.