Transcript Slides For First Report_TC.ppt

Rensselaer Polytechnic Institute
Master’s Project
MANE 6980
Taylor J. Castagna
First Progress Report Presentation on:
The Effect of Cyclic Loading on the Articular Cartilage of the Femoro-Acetabular Joint in
the Absence of a Functional Labrum as Explored through FEA
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Rensselaer Polytechnic Institute
Project Overview
Detailed description of
the femoro-acetabular
joint
1. Labrum
2. Articular
Cartilage
3. Bone
• Significance of the
labrum and it’s
sealing capability
• Introduction to the
finite element
models performed
by Ferguson et al
1. Loads
2. Material Types
3. Poroelasticity
(biphasic
solid/liquid)
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Rensselaer Polytechnic Institute
Finite Element Model
1. Part and Part Geometry
a) Acetabulum
b) Femur
c) Fluid
• Dimensions
• 29 mm radii
2. Assembly
Acetabulum Cartilage with Labrum
Synovial Fluid
Assembly with all parts
Dimensional Example
Femur Articular Cartilage
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Rensselaer Polytechnic Institute
Finite Element Model
(Cont)
3.
4.
5.
Properties for Poroelasticity
•
Solid Phase
•
Lame’s first and
second constant
•
Solid fraction and
void ratio
•
Liquid Phase
•
Linear
permeability
(independent of
strain)
•
Effects of nonlinear
permeability
assumption
Step
•
Soils step used to
calculate fluid pressure
in the voids of material
•
Time period: 1000s
Interactions
•
Contact defined on
surfaces
•
Rigid Impermeable
surface defined at bone
interface
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Rensselaer Polytechnic Institute
Finite Element Model (Cont)
6. Mesh
• Fairly course mesh used
with student edition for
approximation
• CAX4P Fluid
pressure/stress
elements used for
axisymmetric problem
7. Loads and Boundary
Conditions
• Reference point fixed in
space (tied to rigid
surfaces)
• Reference point loaded
with 1200 N
Mesh
Total number of nodes: 664
Total number of elements: 497
360 linear quadrilateral
elements of type CAX4P
137 linear quadrilateral
elements of type CAX4R
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Rensselaer Polytechnic Institute
Finite Element Model (Cont)
8. Results
• Stress (in Mpa)
• Pore pressure (in
Mpa)
• Warnings
• No fluid flow
across contact
surfaces!
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