Date of Award

6-2011

Degree Name

MS in Mechanical Engineering

Department

Mechanical Engineering

Advisor

Stephen M. Klisch

Abstract

A poroelastic finite element model of a heterogeneous articular cartilage disc was

created to examine the tissue response to low amplitude (± 2% strain), low

frequency (0.1 Hz) dynamic unconfined compression (UCC). A strong correlation

has been made between the relative fluid velocity and stimulation of

glycosaminoglycan synthesis. A contour plot of the model shows the relative fluid

velocity during compression exceeds a trigger value of 0.25 μm/s at the radial

periphery. Dynamic UCC biochemical results have also reported a higher

glycosaminoglycan content in this region versus that of day 0 specimens. Fluid

velocity was also found not to be the dominant physical mechanism that

stimulates collagen synthesis; the heterogeneity of the fluid velocity contour plot

conflicts with the homogeneous collagen content from the biochemical results. It

was also found that a Tresca (shear) stress trigger of 0.07 MPa could provide

minor stimulation of glycosaminoglycan synthesis. A feasibility study on

modeling a heterogeneous disc was conducted and found convergence issues with

the jump in properties from the superficial to middle layers of the disc. It is

believed that the superficial layer contains material properties that allow the tissue

to absorb much of the compressive strain, which in turn increases pressure and

causes convergence issues in ABAQUS. The findings in this thesis may help

guide the development of a growth and remodeling routine for articular cartilage.

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