Master's Theses

Date of Award

2013

Document Type

Thesis

Department

Biomedical Engineering

First Advisor

Steven Nicoll

Keywords

cartilage, biomechanics, synovial fluid

Abstract

The purpose of this research thesis project was to develop a mechanical testing device that could enable us to load articular cartilage with a rolling/sliding motion. This novel device was then used to observe the effect of a rolling motion on the fluid film thickness of different lubricants (motor oil, synovial fluid and Hyaluronic Acid (HA)) to varying loads (1kg, 2,kg, 3kg and 4kg) and speeds (10, 25, 48 and 91 mm/s) applied on the sample fluids for 10 cycles. We were able to examine the effect of different speeds within each load for each of the fluid that was tested. With higher speeds, the film thickness of both HA and synovial fluid appeared to decrease, which is an expected behavior a thixotropic fluid. The motor oil, on the other hand, did not follow this trend even though it is a thixotropic fluid. As motor oil has a higher viscosity at lower shear rates, it is possible that the oil being was pushed out of the well containing the sample instead of flowing around the indenter. This problem could be solved by altering the well dimensions so that the sample fluid does not overflow or spill. While the device performed well during calibration, during the actual fluid tests there appeared to be an artifact in the film thickness reading. When the load was changed the vertically placed displacement transducer (LVDT) measurements seemed to fluctuate and may have been do to the LVDT not being firmly held in place. By altering the holder containing the vertical LVDT this error can be avoided in the future. Thus we were not able to compare the fluid film thicknesses between the various loads and fluid samples.

 
 

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