0
research-article

Effect of Contact Area on the Wear and Friction of UHMWPE in Circular Translation Pin-on-Disk Tests

[+] Author and Article Information
Vesa Saikko

Aalto University School of Engineering Department of Mechanical Engineering P.O. Box 14300 Aalto FI-00076, Finland
vesa.saikko@aalto.fi

1Corresponding author.

ASME doi:10.1115/1.4036448 History: Received October 07, 2016; Revised March 09, 2017

Abstract

Circular translation pin-on-disk (CTPOD) tests were performed for ultrahigh molecular weight polyethylene (UHMWPE) with a view to reproducing wear mechanisms that prevail in total hip prostheses. The contact surface diameter varied from 3.0 mm to 30 mm while the slide track diameter was fixed, 10 mm. The counterface was polished CoCr and the lubricant was diluted alpha calf serum. Either the nominal contact pressure (1.1 MPa) or the load (126 N) was kept constant. With a constant contact pressure, the wear factor decreased steeply when the contact diameter exceeded the slide track diameter, apparently because the wear debris was not readily conveyed away from the contact. With constant load, both the wear factor and coefficient of friction increased linearly with increasing contact area. This trend was in agreement with clinical observations that the wear rate of UHMWPE acetabular cups increase with increasing femoral head size. With nominal contact pressures approaching 10 MPa however, the bearing surface topography markedly differed from clinical observations. This was probably due to overheating of the contact and plastic deformation that resulted in the formation of protuberances not seen clinically. The present study emphasized the importance of test parameters in the pin-on-disk wear screening of prosthetic joint materials. It appeared that the contact surface diameter of the flat-on-flat test should be below the slide track diameter and that the nominal contact pressure should be of the order of 1 MPa.

Copyright (c) 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In