Friction between articulating surfaces cause temperature rise in the acetabular cup and femoral head. This heating may influence the rate of wear, fatigue, creep and oxidative degradation of bearing ...materials. The objective of this study is to determine the effect of surface patterning on frictional temperature rise of the articulating surfaces of vitamin E blended ultra-high molecular weight polyethylene acetabular component paired with a cobalt–chromium (CoCrMo) femoral component. For this reason concave dimples were formed on inner surface of the acetabular cup with 0.5mm diameter and 0.5mm depth. Temperature rise between the bearing surfaces was measured under different loading conditions. Frictional measurements of the joints were carried out on a custom made hip joint friction experimental set up. The prostheses were of 28mm diameter. Applied static loads were changed from 200N to 1500N. In the flexion–extension plane, a simple harmonic oscillatory motion between ±24° was applied to the ultra high molecular weight polyethylene acetabular component. The frequency of motion was 1Hz and the tests were run up to 11,000 cycles. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. Lower temperature rise in patterned sample pairs were measured than unpatterned samples. So it can be said that the surface patterning contributes to reduction of frictional heating of sliding surfaces.
•Surface dimples were machined on the inner surface of the acetabular cup samples.•Significant temperature rise was measured between acetabular cup and femoral head.•Surface patterning contributed to reduction of frictional heating on samples.•Temperature rise of UHMWPE and VE-UHMWPE samples were compared.•Lower temperature rise was measured for VE-UHMWPE than conventional UHMWPE.
The measurement of roughness on machined metal surfaces is of considerable importance to manufacturing industries as the roughness of a surface has a significant influence on its quality and function ...of products. In this paper, an experimental approach for surface roughness measurement has been based on the comparison of roughness values taken from the stylus and optical type instruments on the machined metal surfaces (turning, grinding and milling) is presented.
Following this experimental study, all measured surface roughness parameters have been analyzed by using Statistical Package for Social Science (SPSS 15.0) statistically and mathematical models for the two most important and commonly used roughness parameters
R
a
and
R
z
have been developed so that
R
a
=
R
a
(
F,
P,
C) and
R
z
=
R
z
(
F,
P,
C,
M), whereas
F expresses feed,
P periodicity,
C contrast and
M the type of material. The statistical results from numerous tests showed that there has been a correlation between the surface roughness and the properties of the surface topography and there have been slight differences among three measurement instruments on machined metal surfaces in this experimental study.
► We measured flat and spherical samples. ► We used stylus profilometer, infinite focus and confocal laser scanning microscopes. ► We obtained the mathematical models of Ra and Rz roughness ...parameters.
The quantitative determination of surface roughness is of vital importance in the field of precision engineering. This paper presents an experimental study of the roughness analyses for the flat and spherical surfaces of machined metal in order to compare the roughness data taken from the cloud data produced by the stylus type profilometer and two optical-based measurement instruments, namely the infinite focus microscope and the confocal laser scanning microscope.
In this experimental study, the roughness measurements for fifteen flat and six spherical surfaces were repeated six times using three different measurement instruments. Great care was paid to measure the same location for each measurement. For the comparison of the measurement techniques, the same measurement process was applied to the flat and spherical surfaces individually, and the configurations of the measurement instruments (filter type, cut-off, resolution etc.) were synchronized.
R
a
, two-dimensional (2D) roughness parameter and
S
a
, three-dimensional (3D) roughness parameter were also compared. The measurement results for the samples having spherical surfaces indicated a considerably high difference in values taken from the stylus profilometer and two optical-based measurement instruments in contrast to those for flat surfaces.
•Temperature rise was measured between acetabular insert and femoral head.•Experiments were conducted with a custom made hip joint friction simulator.•Temperature rise of UHMWPE was theoretically ...calculated.•Theoretical and experimental results were comparable.•Lower temperature rise was measured for VE-UHMWPE than conventional UHMWPE.
Frictional heating of articulating surfaces may influence the rate of wear, fatigue, creep and oxidative degradation of bearing materials. Also temperature rise can damage the surrounding tissue and lubricant around the artificial joint and contributes insert loosening. The objective of this study is to determine temperature rise between sliding surface of vitamin E blended UHMWPE and conventional UHMWPE acetabular component paired with a cobalt–chromium–molybdenum (CoCrMo) femoral component, as a function of sliding time and applied load. Besides the experimental studies, the frictional temperature rise of conventional UHMWPE was theoretically calculated. Frictional measurements of the joints were carried out on a custom made hip joint friction simulator. The diameter of the prostheses was 28mm. Applied static loads were changed from 200N to 1500N. In flexion–extension plane, a simple harmonic oscillatory motion between ±24° was applied to the UHMWPE acetabular component. The period of motion was 1Hz and the tests were run up to 11,000 cycles. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. Both the experimental temperature rise values and theoretical calculations results were compared and evaluated.
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