Frictional Characteristics of Tilting Pad Bearings According to Pattern Arrangement on Rough Surface Considering Asperity Contact

Generally, when two surfaces in contact move relative to each other, friction, wear, and lubrication occur. One of the methods for changing the characteristics of two surfaces in relative motion is to process a pattern on a surface; this method is referred to as surface texturing. Studies have used various approaches to identify friction characteristics through patterns. However, relatively insufficient research has been conducted on array of patterns. As the pressure of surface lubricants can vary depending on the arrangements of patterns, it is necessary to understand the friction characteristics with respect to the arrangements. In this study, the friction effect according to the shape and arrangement of the pattern was evaluated through friction experiment that takes into account the slope effect and the asperity contact, and proposed and executed a new method for the lubrication analysis of the rough surfaces. The patterns and roughness were produced by laser processing and particle jetting (AAJ) of the experimental specimens and friction experiments were performed with the fabricated specimens. The new lubrication analysis was performed for the four types of patterns (Reference surface, X-direction-line groove, X-direction-line + zigzag groove, X-direction-zigzag + line groove). The validity of the analysis was verified by comparing the results from the experiment and analysis under the same pattern and friction conditions. The results from the friction experiment and lubrication analysis showed a similar tendency to that of the friction coefficient. As a result of the lubrication analysis, it was found that the friction characteristics according to the arrangement of the pattern may have greater or smaller friction compared to the reference surface when considering the influence of the slope. Although it did not appear clearly in the experiment due to limitations in the experimental conditions, it was confirmed that the lubrication analysis and experimental results were similar. As a result of analyzing the friction phenomenon appearing from the application of various arrangement of patterns considering asperity contact, it was possible to identify an effective pattern arrangement for reducing friction.