Influence of temperature distributions in EHL film on its thickness under high slip ratio conditions

Tsunamitsu Nakahara, Kazuyuki Yagi

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

This paper describes the influence of temperature rise of oil film in Hertzian contact area on the film thickness or profile under high slip ratio conditions. Temperatures of both surfaces of a ball and a disk as well as average temperature across the oil film were measured by means of an improved infrared. Two kinds of optical band-pass filters were used to separate the radiations from the ball surface and the oil film through an infrared transparent disk made of sapphire glass. In case of temperature measurement of the disk surface, another sapphire glass disk was coated with 300 nm chromium layer on the contact surface to radiate the infrared from the disk surface and also to intercept the radiation from the ball surface and the oil film. Temperature profiles across the oil film were estimated by assuming a parabolic profile with the measured three kinds of temperatures. For case within 200% in slip ratio, both minimum and central film thickness decreased under constant entrainment velocity as slip ratio increased. Measured film shapes were not flat at central Hertzian contact region under high-slip condition and differed from the results by the conventional EHD theory assuming constant viscosity in the direction of film thickness. The profile of Couette flow varied due to the distribution of oil film temperature in thickness direction. The viscosity wedge action, that is the variation of the profile of Couette flow causes reduction of film thickness or deformation of film profile. For case over 200% in slip ratio, the relation between central film thickness and slip ratio under constant relative slide speed had a great difference from the results calculated from the formula presented by Chittenden et al.

Original languageEnglish
Pages (from-to)632-637
Number of pages6
JournalTribology International
Volume40
Issue number4
DOIs
Publication statusPublished - Apr 1 2007
Externally publishedYes

Fingerprint

Temperature distribution
temperature distribution
slip
Oils
oils
Film thickness
film thickness
balls
profiles
Aluminum Oxide
Couette flow
Infrared radiation
Sapphire
Temperature
sapphire
temperature
Viscosity
viscosity
Radiation
Glass

All Science Journal Classification (ASJC) codes

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

Cite this

Influence of temperature distributions in EHL film on its thickness under high slip ratio conditions. / Nakahara, Tsunamitsu; Yagi, Kazuyuki.

In: Tribology International, Vol. 40, No. 4, 01.04.2007, p. 632-637.

Research output: Contribution to journalArticle

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