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Title: Nanoindentation Results from Direct Molded vs. Machined UHMWPE Tibial Bearings

Nanoindentation has been used to compare the micromechanical properties of direct molded vs. machined bearing surfaces on UHMWPE tibial components. Differences in micromechanical properties (hardness and elastic storage modulus) were observed between these two types of bearing surfaces, and are believed to result from (1) differences in surface roughness, and (2) differences in morphology of the UHMWPE. Clinical studies of in-vivo UHMWPE wear rates in acetabular cups have reported differences between direct molded and machined bearings.{sup 1,2} Other studies of retrieved components have reported differences as well.{sup 3} Variations in surface characteristics (rather than bulk properties) may cause these differences in wear behavior. This study's objective was to compare micro-mechanical interactions at the bearing surfaces of direct molded components with those of machined components. A nanoindenter was used to perform instrumented microindentations on these surfaces. Da ta was analyzed to study both the load vs. displacement behavior during the indentation cycle, and also to measure the elastic storage modulus and hardness as a function of depth.
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
14617
Report Number(s):
ORNL/CP-104808
TRN: AH200129%%341
DOE Contract Number:
AC05-96OR22464
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 13 Nov 1999
Research Org:
Oak Ridge National Lab., TN (US)
Sponsoring Org:
USDOE Office of Science (US)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BEARINGS; HARDNESS; IN VIVO; MORPHOLOGY; ROUGHNESS; STORAGE