This report focuses on study of behavior of a human knee cartilage on application of point load. A cartilage is a tissue which covers the long bones at the knee joint.it is known as articular cartilage in the medical world. It prevents osteoarthritis and other knee related injuries. The main challenge of this project was to define material properties of bone and cartilage in ANSYS workbench. Initially the physical structure and function of knee bone and cartilage is defined and all the material properties are defined in workbench and in the subsequent section a thorough explicit analysis is done on ANSYS workbench and force vs displacement, internal energy-time graphs are plotted. Next, a structural and 2D analysis done in ANSYS –APDL. Next an explicit analysis done in LS-Dyna and plots for displacement-force and Internal energy-time are determined.

1. Design and Analysis of
Human knee and cartilage
Name of student Guided by
Neeraj Jat Prof. K. Nema
Shaunak Chandwadkar
Ketul Shah
Amey Vaidya
Sridutt Gokul
1

2. Outline
• Objective
• Introduction
• Theoretical Background
• Modeling details
• Results and Discussion
• Conclusion & Future scope

3. Objective
• To study stress and deformation phenomena of a human knee
cartilage subjected to displacement and velocity applied in a form of
impact
• Determining cartilage properties and modelling its response
• Comparison of Reaction Force obtained from different simulation
software and experimental data to justify our model
• Provide pathway for further experiments for making Artificial
cartilage.

4. Introduction
• Cartilage is a fine viscoelastic rubbery tissue which acts as a cushion
between the bones and the joints. People with cartilage damage
commonly experience joint pain , stiffness and swelling
• Causes of cartilage damage:
• Direct blow: If a joint receives a heavy impact
• Wear and tear: A joint that experience a long period of stress
• Lack of movement : Long hours sitting due to nature of job etc.
• Current treatments available:
• Knee replacement
• Knee prosthesis
Statistical Survey and Motivation

5. • Bone: The femur, or thigh bone, is the longest, heaviest, and
strongest bone in the entire human body
• The cartilage has the thickest layer between these two bones
• Most of the injuries occur to the Knee
and hence it is chosen for modelling and
analysis
Theoretical Background

6. Modelling Details
Modelling
• Mimics (Materialise’s Interactive Medical Image Control System)
• Easily and quickly create accurate 3D models from imaging data
• Accurately measures in 2D and 3D
• Exports 3D models to 3matic to optimize the mesh for FEA

7. Modelling Details
Slicing femur bone from the big geometry
Extrusion of cartilage over bone surface
Creating virtual cells using virtual topology for simplifying geometry

8. Modelling Details
2D 3D
Mesh size for cartilage: 0.1 mm
Mesh size for Bone: 1mm (finer meshing)
Mesh size for sphere: 0.3 mm
Mesh type: Quad
Tested for: Static condition
Between cartilage and bone: Bonded
Between cartilage and sphere: Bonded
Fixed support: Bone
Simply supported: Cartilage
Analysis load: Via sphere displacement
0.05 mm total displacement.
Mesh size for cartilage: 1 mm
Mesh size for Bone: 3mm (finer meshing)
Mesh size for sphere: 0.5 mm
Mesh Type: Tetrahedrons
Tested for: Static condition and Explicit
Between cartilage and bone: Bonded
Between cartilage and sphere: Bonded
Fixed support: Bone
Analysis load-static: Via sphere
displacement
Analysis load-dynamic: velocity.
0.05 mm/s velocity

9. Theoretical Background
Determination of Material properties of bone and cartilage
Material Properties of Bone
Young's Modulus 12600-19400 Mpa
Poission's Ratio 0.3-0.39
Shear Modulus 4850-5700Mpa
Operating Temerature 25 C
Density 1800 kg / m^3
Material Type Solid
Tensile Strength 50- 135 Mpa
Compressive Strength (-50) to (-250 )Mpa
shear Strength 65 Mpa
Material Properties of Cartilage
Young's Modulus: 0.06-0.020 Mpa
Poission's ratio: 0.45-0.49
Shear Modulus: 0.020 MPa
Temperature: 25 C
Density 1100 kg/m^3
Permiability 10^-15 to 10^-16 m^4/N
Material Type ViscoElastic (Porous)
Material Properties Of Steel
Young's Modulus 180 to 200GPa
Poission's ratio 0.23 to 0.29
Shear modulus 75 to 85 Gpa
Yield strength 250 Mpa
Ultimate Tensile Strength 550 Mpa
Density 7800 kg/m^3

10. Modelling 2D and 3D

11. Modelling knee- static

12. Modelling knee-explicit

13. Experimental Setup
• The Biomomentum’s Mach one machine was used to carry
out the experiments.
• Cartilage Sample: Bovine articular cartilage sample.
• Indentation velocity: 0.0025 mm/s
• Indentation Depth: 0.05 mm
• Sphere radius: 2.5 mm
• Sample dimensions: 1 cm x 1 cm x 1 cm, with cartilage
thickness of 1m

15. Eq Stress 2D and 3D Total Deformation
Results & Discussion

16. Total deformation and force reaction (Static)
Results & Discussion

17. Results & Discussion
Equivalent stress and total deformation (Explicit)

18. Force reaction for 2D and experimental
-0.00005
0
0.00005
0.0001
0.00015
0.0002
0.00025
0.0003
0.00035
0.0004
0 1 2 3 4 5 6 7
Force Reaction (Y) [N]
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 10 20 30 40 50 60 70 80
Chart Title
Series1 Series2 Series3 Series4
Results & Discussion

19. Force reaction for 3D knee-static and experimental
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 10 20 30 40 50 60 70 80
Chart Title
Series1 Series2 Series3 Series4
Results & Discussion
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 10 20 30 40 50 60 70 80
Force reaction 3D Knee static

20. Force reaction for 3D knee-explicit and experimental
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 10 20 30 40 50 60 70 80
Chart Title
Series1 Series2 Series3 Series4
Results & Discussion
-1.00E-01
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Force Reaction - 3D Knee ansys -Expilicit

21. Force reactions LS dyna vs Experimental
•
0.00E+00
5.00E-07
1.00E-06
1.50E-06
2.00E-06
2.50E-06
3.00E-06
3.50E-06
4.00E-06
4.50E-06
5.00E-06
0 200 400 600 800 1000 1200
ReactionForce
Time
Force Reaction ls-dyna Explicit
Results & Discussion

22. Conclusion
• The force reaction graph of all analysis shows the behaviour matches
the experimental behaviour of the cartilage.
• Although not exactly as the cartilage, however as Cartilage is a Visco-
Elastic Bio material. And impossible to replicate, The results obtained
are pretty good as expected.
• This study can be further utilized to take a step towards in attempt of
making an artificial cartilage, Solving all the problems mentioned in
the introduction part of the project.