Experimental technique to study tangential-to-normal contact load ratio

Jamil A. Abdo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


This paper considers the mechanical interaction due to surface roughness and examines the surface theories using the classical definition of coefficient of friction: the tangential-to-normal load ratio. The postulation for maximum static friction is used to experimentally evaluate the contact models. For this purpose, a pin-on-disk test apparatus is employed with the capability of measuring tangential and normal forces for a frictional contact. The tests involve pairs of disks and specimens, that is, steel-on-steel and aluminum-on-aluminum contacts. In each case, profilometer measurements are performed on the disk and the Greenwood and Williamson parameters, are determined. Using the parameters, the theoretical estimates of normal and tangential loads are obtained. The theoretical values of tangential-to-normal contact load ratios are compared with those obtained from measurements for various applied normal loads. The tests utilizing a pin-on-disk apparatus showed a partial agreement between the experimentally obtained load ratios and the predicted upper limit confidence interval using the theoretical elastic and elastic-plastic contact. The result suggested that the elastic-plastic formulations provide better predictions of load ratios than the elastic contact formulations.

Original languageEnglish
Pages (from-to)389-403
Number of pages15
JournalTribology Transactions
Issue number3
Publication statusPublished - Jul 2005


  • Contacting rough surfaces
  • Friction-modeling
  • Static friction

ASJC Scopus subject areas

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


Dive into the research topics of 'Experimental technique to study tangential-to-normal contact load ratio'. Together they form a unique fingerprint.

Cite this