Browsing by Author "Shang, Qingyu"

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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.
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    Influence of Monstera riedrichsthalii bionic textures on the tribological and vibration behavior of rolling bearings
    (2025) Long, Risheng; Shang, Qingyu; Sun, Shaoni; Wang, Siwei; Ma, Chi; Zhang, Jianwei; Marian, Max
    Surface texturing has been proven to be an effective method for improving the lubrication characteristics and tribological behavior of tribo-pairs under various operating conditions. Inspired by the unique Swiss cheese-like leaves of Monstera riedrichsthalii, eight bionic texture patterns were introduced. The influence of vein features, such as costal vein angles (45° and 60°), vein symmetry (symmetric, asymmetric), and elliptical holes, on the tribological and vibration characteristics of rolling bearings was investigated under starved lubrication through a wear test rig and time‒frequency domain vibration signal analysis. The results show that the average coefficients of friction and wear losses of the Monstera riedrichsthalii bionictextured groups are generally lower than those of the smooth reference. The amplitudes and parameters (i.e., peak value, root mean square (RMS), and crest factor) of the time-domain vibration signals of the textured groups are greater than those of the smooth group in the early stages, but the vibration parameters of most textured groups are lower than those of the smooth bearings in the later stages, especially those of the groups with elliptical holes. The amplitudes and power spectral density (PSD) curves of the frequency-domain vibration signals exhibit similar variations to those of the time-domain signals. Compared with the smooth reference, the Monstera riedrichsthalii bionictextured group with a combination of 45° secondary-vein angle, asymmetry, and elliptic holes can provide excellent tribological and vibration performance. Its well-lubricating period, average coefficient of friction (CoF), and mass loss can be effectively prolonged or reduced by 37.4%, 7.3%, and 43.9%, respectively.
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    Synergistic Effects of Graphene-added Lubricants and Surface Micro-texturing on the Tribological Behavior of Thrust Roller Bearings
    (2024) Long, Risheng; Yao, Ying; Zhang, Longen; Shang, Qingyu; Sun, Shaoni; Hu, Jiashuai; Pape, Florian; Marian, Max
    The synergistic effects of graphene additive and surface micro-texturing on the friction and wear properties of rolling bearings are still a research gap. To this end, the tribological behavior of dimples textured thrust roller bearings (81107TN) are investigated under starved lubrication. The lubricants contained different mass fractions (0.06 %, 0.10 % and 0.14 %) of graphene. The evenly distributed dimples (diameter: 60 mu m or 250 mu m; depth: 1 mu m or 8 mu m) were manufactured only on the raceways of the shaft washers. By comparing the coefficients of friction (COF), wear losses and worn surfaces, the influence of various dimples dimensions and mass fractions of graphene on the tribological behavior of rolling bearings is discussed. The results show that appropriate dimple parameters and a suitable mass fraction of graphene can synergistically have a positive effect on the tribological properties of bearings. In this work, the textured group, with a dimple-diameter of 60 mu m and a dimple-depth of 1 mu m, can provide the best comprehensive friction-reducing and wear-reducing performance for the mass fraction of graphene with 0.10 wt%. Compared to the smooth bearings lubricated with base oil, its mean COF is reduced by 31 % and its wear loss by 35 %. This work can be a valuable reference for the improvement of rolling bearings and lubricants.