Week 8-3D Tetra Meshing Challenge

AIM: To Create 3D tetra meshing on the given component.

OBJECTIVE:

1. To Create a Teramesh for Housing component with the following quality criteria.

   TetraMesh Generation Method: 2D to 3D Conversion

   Elements sizes: Min- 2 Units, Target- 5 Units, Max- 7 Units 

   Tet collapse: 0.15

2. For the given model, Create a 3D Tetramesh with the following quality criteria. 

   TetraMesh Generation Method: Quick Tetra Mesh/ Volume Tetra Mesh

   Target Element size: 3 Units.

   Tet Collapse: 0.15

3. For the given assembly model, Create a 3D Tetramesh with the following quality criteria.

   TetraMesh Generation Method: Quick Tetra Mesh/ Volume Tetra Mesh

   Target Element size: 4 Units.

   Tet Collapse: 0.1

• 3D-MESH:  A 3D mesh is the structural build of a 3D-model consisting of polygons. 3D meshes use reference points in X, Y and Z axes to define shapes with height, width and depth.In this there are two types of Meshings can be done.

        1.Tetra elements Meshing.

        2.Hex elements Meshing.

1. 3D-Tetra Meshing.

   Tetrahedral is a four noded solid element which can be generated through the tria element by          creating the volume and also through the existing volume of the geometry. These elements are used where the geometry has high thickness and complexity. This is the most prefered method in industries because it is easy to mesh complex geometry with tetra elements. 

Methods to generate Tetra meshing.

• Conversion of 2D tria elements to tetrahedral elements. (From 3D-tetra mesh panel)
• Using Quick tetra mesh. (From utility panel)
• Using volume tetra mesh panel.

2.Hex Meshing.

Hex Meshing is a standard but complex collection of cubes, commonly used by DEP (Detroit Engineered Products) in variety of meshing techniques, which works as a part of geometry. It is mainly dependent on the computational designs of various shapes. Hex Meshing has zonal boundaries and the internal and external zonal boundaries are free to make use of different zone shapes. Hex Meshing also allows Concept design options, which can help in analyzing geographical and cartographic data.

• Tet collapse.

Tet collapse is one of the quality parameters, which will be checked while generating Tetra elements. It can be calculated by measuring the distance of the node from the opposite face, then each of the four values will be divided by the square root of the opposite faces area. The minimum of four resulting values is then normalized by dividing it by 1.24.

Tet collapse = Min of (h√A1.24)

where, 

h- Height between node 1 and opposite face of the triangle.

A- Area of the opposite face.

PROCEDURE:

1.CONVERSION OF 2D TRIA ELEMENTS TO TETRAHEDRAL ELEMENTS.

• Import the geometry and clean the geometry.
• Delete the solid from the model.
• Mesh the model with the "trias" using 2D Mesh.
• Model should be cleaned with minimum and maximum length elemental errors.
• Now, go to 3D>Tetramesh>Tetra mesh>Fixed trias/quads to tetra mesh (select elements)>Mesh. Reason behind selecting elements under Fixed trias/quads to tetra mesh is, it will match the node location of the volume elements with those of the surface mesh. It guarantees the connectivity of the tetras with the trias. This option will be used whenever there need to match other components to the resulting volume mesh, or when there need to generate layers compose of pentas/Hexas.
• Before meshing Check the Tetramesh parameters and then proceed to mesh.

2. Tetra mesh by using "Quick Tetra Mesh" (from utility panel).

• Import and cleanup the geometry.
• Delete the solid from the model.
• Now, Go to View>Browsers>HyperMesh>Utility>Select Geom/Mesh>Quick Tetramesh>Select component(select and proceed)>Mesh.
• 3D-Tetra mesh will be generated for the selected component.

3.Tetra mesh using Volume tetramesh panel.

• Import and cleanup the geometry.
• Keep the solid in the model and cleanup the geometry if needed defeature the fillets.
• Then, Go to 3D>Tetramesh> Tetramesh parameters (check for -fill voids,fix midnodes and smoothing and set min and max element length also assign the tet collapse value).
• After Tetramesh parameters setting, Go to 3D>Tetramesh>Volume tetra>Enclosed volume (select solid)>element size>Mesh.

1.Create a Teramesh for Housing component with the following quality criteria.

TetraMesh Generation Method: 2D to 3D Conversion

Elements sizes: Min- 2 Units, Target- 5 Units, Max- 7 Units 

Tet collapse: 0.15

Housing component.

Meshed components.

2.For the given model, Create a 3D Tetramesh with the following quality criteria. 

TetraMesh Generation Method: Quick Tetra Mesh/ Volume Tetra Mesh

Target Element size: 3 Units.

Tet Collapse: 0.15

Model 2.

Meshed model.

3. For the given assembly model, Create a 3D Tetramesh with the following quality criteria.

TetraMesh Generation Method: Quick Tetra Mesh/ Volume Tetra Mesh

Target Element size: 4 Units.

Tet Collapse: 0.1

Model 3.

 CONCLUSION:

Through this challenge I have learnt 3D-tetra meshing and also different methods to generate tetra meshing i.e,

1.generating 2D mesh and converting it into 3D tetra mesh using tetramesh panel.

2.Generating 3D tetra mesh directly using volume tetra panel.

3.Generating 3D tetra mesh using quick tetramesh.

I have tried all the three methods to generate tetra mesh, but 2D to 3D conversion method gives the best results that means the quality of the mesh will be more appropriate in this method compared to other two methods. Here, In this challenge the tetramesh has been generated using the respective methods as directed in the challenge.