Journal
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
Volume 81, Issue -, Pages 120-129Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jmbbm.2018.02.014
Keywords
Lubricant film formation; Micro-dimple; Artificial hip joints; in-situ; Lubrication
Funding
- University of Arkansas
- US National Science Foundation (NSF) through Center for Advanced Surface Engineering [OIA-1457888]
- Arkansas EPSCoR Program, ASSET III [OIA-1457888]
- project CEITEC [LQ1601]
- Ministry of Education, Youth and Sports of the Czech Republic under the National Sustainability Program II
- Arkansas Biosciences Institute
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This study evaluates the impact of dimple shapes on lubricant film formation in artificial hip joints. Micro-dimples with 20-50 mu m lateral size and 1 +/- 0.2 mu m depths were fabricated on CrCoMo hip joint femoral heads using a picosecond laser. Tribological studies were performed using a pendulum hip joint simulator to apply continuous swing flexion-extension motions. The results revealed a significantly enhanced lubricant film thickness (>= 500 nm) with micro-dimpled prosthesis heads at equilibrium position after the lubricant film has fully developed. The average lubricant film thickness of dimpled prostheses with square- and triangular-shaped dimple arrays over time is about 3.5 that of the non-dimpled prosthesis (204 nm). Remarkably, the prosthesis with square-shaped dimple arrays showed a very fast lubricant film formation reaching their peak values within 0.5 s of pendulum movement, followed by prosthesis with triangular-shaped dimple arrays with a transition period of 42.4 s. The fully developed lubricant film thicknesses (>= 700 nm) are significantly higher than the surface roughness (approximate to 25 nm) demonstrating a hydrodynamic lubrication. Hardly any scratches appeared on the post-experimental prosthesis with square-shaped dimple array and only a few scratches were found on the postexperimental prosthesis with triangular-shaped dimple arrays. Thus, prostheses with square-shaped dimple arrays could be a potential solution for durable artificial hip joints.
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