3-D (Tetra) Meshing on Rearview mirror

Aim:

To perform a Tetra element meshing for the Rearview mirror component with the given element Quality criteria and kinks and dips on the surface of the component to be avoided.

Theory:

Tetra Rapid:

• The Tetra Rapid algorithm meshes the volume with Tetra Elements.
• The maximum growth rate, which is the approximate growth factor of volume element size from layer to layer while the generation moves towards the interior of the volume.
• With the specified inputs from the user like the maximum and minimum value of the tetra elements which specify the growth rate factor.

Tetra FEM:

• This function automatically creates a Tetrahedral mesh inside selected volumes.
• It is to be used mainly for structural applications and the volumes to have meshed with this function must have been defined using the Define(Volumes) function.

Procedure:

• Import the Rearview mirror component to ansa environment
• The imported Rearview mirror consists of a Support/Holder part, Rotating ball, Convex mirror and fixture for mirror

Fig 1: Rearview mirror:

• Assign a refinement to the component to see all the faces clearly and set a value of 1mm under the perimeter in Mesh module
• After refinement, we need to give a topo to get cons correctly share between the faces and to get the correct faces view.
• Then we need to check for the geometry error and in that, we need to check for single cons, triple cons, collapsed cons, unchecked faces, cracks, etc.

Fig 2: Geometry check

Fig 3: Error solved manually

• Assign the quality criteria and mesh parameters

S.No	Quality Criteria	Value
1	Target/Average length	1
2	Minimum Length	0.5
3	Maximum Length	2
4	Tetcolapse	0.2

Table 1: Quality criteria mentioned in this challenge

Fig 4: Mesh parameters

• The next step is to mesh the geometry with the tria elements and we can choose either ortho tria or tria. If in case we need to mesh the feature like fillet and curved faces we will go with the ortho tria since it captures the features pretty well and in a proper way and in the flat faces we can go with the tria since the tria and ortho tria gives similar results in the flat faces.

Fig 5: Meshed surface with tria elements

Fig 6: Meshing is done on the entire component

• The off elements in the mesh is been corrected by using the reconstruct and smooth options under the Shell mesh option and the MV Free under the Grids options.
• In the volume mesh, we need to define a separate property and to mesh the component with unstructured mesh-like Tetra Rapid or Tetra FEM

Fig 7: Property assigned separately.

Fig 8: Meshing done with Tetra Rapid for the parts

• In the Volume module under the list option, we need to right-click on it and to do remesh with Tetra Rapid or Tetra FEM

Fig 9: Meshed Volume

• The kinks and dips on the surface of the component to be rectified using MV free command under the Grids option

Fig 10: Unstructured Tetra elements

Learning outcomes:

Learned to use Volume mesh and also got the idea of Tetra Rapid vs Tetra FEM.

Studied the structured and unstructured mesh.

Learned to remove the collapse error in the volume mesh.

Conclusion:

The geometry clean up is done properly

Assigned the property, materials, and meshed the component using tria and ortho tria elements.

Initializing the volume and do a Rapid tetra meshing with the provided quality criteria

Link for the Tetra Mesh in Rearview mirror provided below:

https://drive.google.com/drive/folders/1T0HJz3pUy6F7hBw7D2cU5OHTCSnJLbCe?usp=sharing