📝 Abaqus Workflow for Girard 2009 Geometry (Hemisphere + Cylinder)
1. Import Parts

Action: File → Import → Part… → bring in hemisphere + ONH cylinder STEP
files.

Note: Choose 3D deformable solid. Uncheck “Combine into single part” so they
stay separate.

Why: You need two independent solids with different materials.
2. Assembly

Action: Assembly module → Create Instance for each part.

Note: Use Dependent (mesh on part).

Why: Both parts must exist in one model for interactions, BCs, and loads.

Align: If not perfectly positioned, use Instance → Translate/Rotate.

Why: Cylinder must sit inside the canal hole.
3. Mesh Controls & Element Type


Action: Mesh module, for each part:
o
Mesh → Controls → select whole body (cell) → Technique = Free, Shape
= Tet, Algorithm = Medial Axis.
o
Mesh → Element Type → Family = 3D Stress, Quadratic, Tet, Hybrid = ON
→ → element = C3D10H.
Why: Girard modeled sclera/ONH as nearly incompressible → need hybrid
quadratic tetrahedral elements.
4. Seeding

Action:
o
Seed → Part… → global size ~0.15 mm, Curvature control ON (0.05), Min
size control ON (0.05), Growth rate 1.2.
o

Seed → Edges… → refine canal rims (0.05 mm).
Why: Global mesh = efficiency; rim refinement = accuracy around scleral canal.
5. Mesh Generation

Action: Mesh → Part for each solid.

Why: Generates the actual finite element mesh.

Check: Mesh → Verify Mesh → must report 3D elements (C3D10H).
6. Materials

ONH: Create Material → ONH_linear → Elastic → E=0.3 MPa, ν=0.49.

Sclera: Create Material → Sclera_linear → Elastic → E=3 MPa, ν=0.49.

Why: ONH is soft, nearly incompressible; sclera stiffer (simplified linear elastic
for learning).
7. Sections & Assignments

Action: Section → Create (solid, homogeneous) for each material.

Assign → Section…
o
ONH_sec → select cylinder cell.
o
Sclera_sec → select hemisphere cell.

Why: Links material properties to the mesh.

Check: Model Tree → Parts → Section Assignments lists both.
8. Interaction (Tie)


Action: Interaction module → Constraint → Create → Tie.
o
Master = scleral canal wall surface.
o
Slave = outer surface of ONH cylinder.
Why: Glues cylinder and sclera together to act as one continuous structure.
9. Step Definition


Action: Step module → Create Step → Static, General.
o
Name: IOP_step.
o
Nlgeom = ON.
o
Incrementation: Automatic (init 0.05, min 1e-5, max 0.1, max inc 100).
Why: Defines analysis phase where pressure is applied with large deformation.
10. Boundary Condition (BC)


Action: Load module → BC → Create.
o
Step = Initial.
o
Type = Encastre.
o
Apply to equator rim (outer circular edge of hemisphere).
Why: Matches Girard’s “equator clamped” condition.
11. Load (IOP pressure)


Action: Load module → Load → Create.
o
Step = IOP_step.
o
Type = Pressure.
o
Apply to inner surface of hemisphere.
o
Magnitude = 0.006 MPa (≈ 45 mmHg).
Why: Simulates intraocular pressure.
12. Job & Run

Action: Job module → Job → Create → Name = girard_run.

Why: Prepares solver input.

Then: Right-click job → Write Input (to save .inp).

Submit → Monitor until “Completed.”
13. Post-Processing

Action: Results module → open job’s .odb.
o
Plot → Deformed + Contours → U Magnitude.

Why: Visualize scleral canal deformation under pressure.

Optional: Request reaction forces at equator to confirm load balance.