A study of mechanical shear bands in liquids at high pressure

Scott Bair*, Clare McCabe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


Shear localization has been observed in liquid lubricants flowing at high pressure. Two kinds have been identified: for stress-controlled plane Couette shear at high values of Nahme No., thermal runaway can result in the appearance of a band at mid-plane where the temperature and shear rate become localized. Alternatively, at high pressure and high shear stress, intermittent slip can be visualized along inclined bands for both planar Couette shear and squeeze film flows. These mechanical shear bands are responsible for the rate independent behavior that characterizes the traction transferred across the lubricant film in concentrated contact. We consider three models for shear band formation: Mohr-Coulomb slip, loss of ellipticity of Navier-Stokes equations, and non-monotonic stress-strain rate response. The observations that slip occurs for a ratio of shear to normal stress of about 0.1 and that bands form in two characteristic directions support both the Mohr-Coulomb failure criterion description and a change of character of the governing differential equations. Some evidence of constitutive instability is also presented; however, band orientation does not support this model.

Original languageEnglish
Pages (from-to)783-789
Number of pages7
JournalTribology International
Issue number10
Publication statusPublished - Oct 2004


  • High pressure
  • Limiting shear stress
  • Localization
  • Molecular simulation
  • Normal stress difference
  • Shear bands

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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