Browsing by Author "Zhang, Yimin"

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    From Experimentation to Optimization: Surface Micro-Texturing for Low-Friction and Durable PTFE–Steel Interfaces Under Full Film Lubrication
    (Multidisciplinary Digital Publishing Institute (MDPI), 2024) Long, Risheng; Hou, Jincheng; Zhang, Yimin; Shang, Qingyu; Ma, Chi; Pape, Florian; Marian, Max
    To enhance the sliding tribological performance between PTFE and 40#steel (AISI 1040) under full film lubrication conditions, laser surface texturing (LST) technology was employed to prepare micro-dimples on the contact surfaces of 40# steel discs. The Box–Behnken design response surface methodology (BBD-RSM) was applied to optimize the micro-dimple parameters. Coefficients of friction (COFs), wear losses and worn contact surfaces of the PTFE–40# steel tribo-pairs were researched through repeated wear tests, as lubricated with sufficient anti-wear hydraulic oil. The influencing mechanism of micro-dimples on the tribological behavior of tribo-pairs was also discussed. The results proved that micro-dimples can significantly improve the tribological properties of PTFE–40#steel tribo-pairs. The deviation between the final obtained average COF and the prediction by the BBD-RSM regression model was only 0.0023. Following optimization, the average COF of the PTFE–40# steel tribo-pair was reduced by 39.34% compared to the smooth reference. The wear losses of the PTFE ring and 40# steel disc decreased by 91.8% and 30.3%, respectively. This study would offer a valuable reference for the optimal design of key seals used in hydraulic cylinders.
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    Influence of micro-texture radial depth variations on the tribological and vibration characteristics of rolling bearings under starved lubrication
    (2024) Long, Risheng; Sun, Yuhao; Zhang, Yimin; Shang, Qingyu; Ramteke, Sangharatna M.; Marian, Max
    Surface micro-texturing involves creating microscopic pits or textures, serving as lubricant reservoirs to enhance lubrication distribution, potentially reducing friction and wear. This study specifically delves into the influence of varied depth patterns of pits on the operational performance of textured rolling bearings under severe lubrication conditions. Five distinct patterns with a fixed pit diameter (250 mu m) and different depth variations (concave, decreasing, increasing, convex, and horizontal) were introduced on the shaft rings of cylindrical roller thrust bearings using the laser marking method. Wear tests were conducted under starved lubrication condition. Wear loss and signal analysis highlight the profound effect of depth variations, whereby bearings with shallow pits near the outer side of their working surfaces exhibit longer lubrication times, improved tribological performance, and enhanced vibration characteristics. Notably, the convex pattern stands out for providing comprehensive and favorable tribological and vibration properties. This research contributes valuable insights for the optimal design of micro-textures for rolling bearings, paving the way for enhanced efficiency and reliability in mechanical systems.