中国物理B ›› 2013, Vol. 22 ›› Issue (1): 16202-016202.doi: 10.1088/1674-1056/22/1/016202

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

A dynamic rheological model for thin-film lubrication

张向军, 黄颖, 郭岩宝, 田煜, 孟永钢   

  1. State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
  • 收稿日期:2012-04-06 修回日期:2012-07-10 出版日期:2012-12-01 发布日期:2012-12-01
  • 基金资助:
    Project sponsored by the National Basic Research Program of China (Grant No. 2012CB934101) and the National Natural Science Foundation of China (Grant Nos. 50975154 and 51175282).

A dynamic rheological model for thin-film lubrication

Zhang Xiang-Jun (张向军), Huang Ying (黄颖), Guo Yan-Bao (郭岩宝), Tian Yu (田煜), Meng Yong-Gang (孟永钢)   

  1. State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
  • Received:2012-04-06 Revised:2012-07-10 Online:2012-12-01 Published:2012-12-01
  • Contact: Zhang Xiang-Jun E-mail:xjzhang@mail.tsinghua.edu.cn
  • Supported by:
    Project sponsored by the National Basic Research Program of China (Grant No. 2012CB934101) and the National Natural Science Foundation of China (Grant Nos. 50975154 and 51175282).

摘要: In this study, the effects of the non-Newtonian rheological properties of lubricant in the thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time λ0, were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime.

关键词: rheology, viscoelasticity, Deborah number, thin-film lubrication

Abstract: In this study, the effects of the non-Newtonian rheological properties of lubricant in the thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time λ0, were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime.

Key words: rheology, viscoelasticity, Deborah number, thin-film lubrication

中图分类号:  (Friction, tribology, and hardness)

  • 62.20.Qp
68.35.Fx (Diffusion; interface formation) 81.40.Pq (Friction, lubrication, and wear)