中国物理B ›› 2017, Vol. 26 ›› Issue (7): 74601-074601.doi: 10.1088/1674-1056/26/7/074601

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Relationship between the real contact area and contact force in pre-sliding regime

Baojiang Song(宋保江), Shaoze Yan(阎绍泽)   

  1. State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
  • 收稿日期:2016-10-13 修回日期:2016-12-15 出版日期:2017-07-05 发布日期:2017-07-05
  • 通讯作者: Shaoze Yan E-mail:yansz@mail.tsinghua.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No.11272171),the Natural Science Foundation of Beijing City,China (Contract No.3172017),and the Education Ministry Doctoral Fund of China (Grant No.20120002110070).

Relationship between the real contact area and contact force in pre-sliding regime

Baojiang Song(宋保江), Shaoze Yan(阎绍泽)   

  1. State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
  • Received:2016-10-13 Revised:2016-12-15 Online:2017-07-05 Published:2017-07-05
  • Contact: Shaoze Yan E-mail:yansz@mail.tsinghua.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No.11272171),the Natural Science Foundation of Beijing City,China (Contract No.3172017),and the Education Ministry Doctoral Fund of China (Grant No.20120002110070).

摘要: The pre-sliding regime is typically neglected in the dynamic modelling of mechanical systems. However, the change in contact state caused by static friction may decrease positional accuracy and control precision. To investigate the relationship between contact status and contact force in pre-sliding friction, an optical experimental method is presented in this paper. With this method, the real contact state at the interface of a transparent material can be observed based on the total reflection principle of light by using an image processing technique. A novel setup, which includes a pair of rectangular trapezoidal blocks, is proposed to solve the challenging issue of accurately applying different tangential and normal forces to the contact interface. The improved Otsu's method is used for measurement. Through an experimental study performed on polymethyl methacrylate (PMMA), the quantity of contact asperities is proven to be the dominant factor that affects the real contact area. The relationship between the real contact area and the contact force in the pre-sliding regime is studied, and the distribution of static friction at the contact interface is qualitatively discussed. New phenomena in which the real contact area expands along with increasing static friction are identified. The aforementioned relationship is approximately linear at the contact interface under a constant normal pressure, and the distribution of friction stress decreases from the leading edge to the trailing edge.

关键词: real contact area, contact interface, pre-sliding regime, contact force

Abstract: The pre-sliding regime is typically neglected in the dynamic modelling of mechanical systems. However, the change in contact state caused by static friction may decrease positional accuracy and control precision. To investigate the relationship between contact status and contact force in pre-sliding friction, an optical experimental method is presented in this paper. With this method, the real contact state at the interface of a transparent material can be observed based on the total reflection principle of light by using an image processing technique. A novel setup, which includes a pair of rectangular trapezoidal blocks, is proposed to solve the challenging issue of accurately applying different tangential and normal forces to the contact interface. The improved Otsu's method is used for measurement. Through an experimental study performed on polymethyl methacrylate (PMMA), the quantity of contact asperities is proven to be the dominant factor that affects the real contact area. The relationship between the real contact area and the contact force in the pre-sliding regime is studied, and the distribution of static friction at the contact interface is qualitatively discussed. New phenomena in which the real contact area expands along with increasing static friction are identified. The aforementioned relationship is approximately linear at the contact interface under a constant normal pressure, and the distribution of friction stress decreases from the leading edge to the trailing edge.

Key words: real contact area, contact interface, pre-sliding regime, contact force

中图分类号:  (Tribology and mechanical contacts)

  • 46.55.+d
42.30.Va (Image forming and processing) 78.20.Ci (Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity))