Week 8-3D Tetra Meshing Challenge

Objective:-

1. To create tetra mesh for cover and hub, crank housing, and suspension assemblies according to the given quality criteria.
2. For cover and hub, the target size, minimum size and maximum size of the element is 5mm, 2mm, and 7mm respectively.
3. For crank housing and suspension assembly, the target size is 6mm. Tet collapse is set at 0.15 for both models.

Tetrahedral is a four- nodded solid element that can be generated through the tria element by creating a volume and also through the existing volume of the geometry. These elements are used where the geometry has high thickness and complexity.

Volume Meshing can be done using 3 methods

1. 2D to 3D Conversion.
2. Quick tetra meshing.
3. Volume tetra meshing.

Method 1:- 2D to 3D Conversion:-

Method 2:- Quick tetra Meshing:-

1. Import the model.
2. Delete the Solid from the cad model.
3. Then click on View menu>Browsers>Hypermesh> Utility
4. Select Geom/Mesh from the Utility tab
5. Then choose Quick Tetra mesh from the mesh tools.
6. Then from the Quick tetra tab, click on components and choose the component which we want to mesh.
7. Give mesh size
8. Choose only Trias from mesh type
9. Click on Mesh.
10. Then you will see dialogue as Surface mesh completed Attempted tetra mesh Click on OK to proceed
11. After Quick tetras in the components list, you can see that there is a new component added named Quick tets, this means the quick tetra mesh is done.
12. Also, we should check and confirm the presence of tetra mesh by masking.

Method 3:- Volume meshing:-

1. Import the model.
2. In this method, we need a solid model.
3. For Volume, mesh go to, 3D> Tetra mesh> Volume tetra mesh.
4. Choose Solids under Enclosed volume.
5. Select the solid which we want to mesh.
6. Give elements size.
7. 2D element type as trias 
8. 3D element type as tetras.
9. Wisely check the boxes of Use Curvature, Use Proximity. Because always choosing the both will make some deformations or sometimes make a 2D mesh instead of 3D
10. Also for auto cleanup of the solid check the Cleanup elements option.
11. Click on the mesh.

Methodology

1. Import the geometry into HyperMesh.
2. Cleanup the geometry
3. Deploy mesh according to the given quality criteria
4. Remove free edges and T-junctions if they were created in the 2D tria mesh.
5. Check if elements have failed for tet collapse and rectify them.

Procedure

A. Cover and hub

1. The cover and hub were imported into Hypermesh and the model was checked for free edges and other geometric issues.
2. Both cover and hub were meshed using Quick Tetramesh from View > Browsers > HyperMesh > Utility > Quick Tetramesh.
3. The model was checked for tet collapse in Tools > check elements > 3D > tet collapse and it was found that no elements were failing.
4. Given below is the 3D tetra mesh of the hub.

B. Model_2

1. The model_2 was imported into Hypermesh and the model was checked for free edges and other geometric issues.
2. The component was 2D meshed with tria using 2D > auto mesh. This 2D mesh was converted into tetra mesh using 3D > tetra mesh > Tetra mesh > set elements in Fixed tria/quads to tetra mesh > mesh.
3. The mesh was checked for tet collapse and 43 elements were failing. The failing elements were fixed using 3D > tetra mesh > Tetra mesh > fix 3D elements > Tetra collapse was set to 0.15 > fix. 
4. When the mesh was checked again for tet collapse, no elements were failing.

C. Turbo Charger

1. The turbocharger assembly has meshed with tria first with a target size of 6mm. While tetra meshing this component, the 3D mesh could not be deployed because of a T junction in the feature given below.
2. Therefore, a finer mesh was deployed in this region to avoid the T-junction and tetra mesh was created using 3D > tetra mesh.
3. The elements failing for tet collapse were fixed using 3D > tetra mesh > fix 3D elements. No elements were failing when it was checked for failure criteria.