Developing Structural Tetra Meshing for a Rear-View Mirror & Defining its Volume using ANSA

ABSTRACT:

• By using CAE Pre-Processing Tool ANSA & to develop Tetra meshing for a Rear-View Mirror

METHODOLOGY:

1. Importing the CAD geometry in ANSA
2. Checking out the errors and Assigning Property ID (PID) for each surface.
3. Assigning Quality Criteria
4. Meshing and Improving Mesh Quality (Ortho Tria & Tria Mesh is used).
5. Generating Volume Mesh

INTRODUCTION:

Keeping safety, strength, and many design aspects, Rear View Mirror has to undergo many conditions, and final CAD outcome is considered for pre-processing in ANSA.

PROCEDURE:

1. Importing CAD Geometry of Rear View Mirror in ANSA:

• After successfully importing the Bottle Cap CAD geometry we need to give the Target Length/ Average Length which is assigned as 1 under Mesh Mode<Perimeters

2. Checking Out for Errors and Assigning Property ID (PID) for each Surface:

• We need to perform the geometry check under CHECKS Manager in order to see any geometrical problems of the model such as Unmeshed Macros, Unchecked Faces, Needle Faces, Collapsed Cons, Triple Cons, Overlaps and Cracks.
• ANSA detects some errors and we need to ensure that these need to fixed manually or by just running the automatic fix command and confirm that there are no geometry errors there in the model.
• For any component, we need to assign Property ID(PID) for each and every part so as to differentiate individual checks in our process in later stages.
• This helps in switching to different parts specified upon user requirements.
• Make sure that the Bottle Cap is always Gray which indicates Positive in ANSA where yellow stands as Negative.
• Use the Orient option under Faces in Topo Mode to change the color of the model to Gray if it’s so. (Orient<Visible)

3. Assigning Quality Criteria:

• The average length alters the shell element length of the component.
• Remaining values are assigned in the Quality Manager or just tapping F11 key.
• Each element in the Mesh should qualify the Quality Criteria given.
• After assigning the values given for the quality check, we need to perform the topological clean up before meshing.

Topological Clean-Up:

• So as to acquire the smooth flow of mesh a CAE engineer should do topological clean-up for each and every corner of the model and examine, remove unwanted CONS by using different options available under Module Buttons, mostly used keys are cut, release, insert & delete.

4. Meshing and Improving Mesh Quality (Ortho Tria & Tria Mesh is used):

Meshing:

• After Topological Clean up, consider meshing each and every part separately.
• Assigning the Mesh Quality with Ortho Tria & with 1st order elements.
• One can use different methods in order the Mesh the surfaces, I used the Spot Meshing option under Mesh Generation in Mesh Modules Buttons.
• Spot ensure the user a good Mesh flow across the selected part and ANSA provides a decent outcome for the selected region.
• Once the Meshing is done, try to reconstruct the Mesh generated and Smooth it for enhancing the Mesh.

Improving Mesh Quality:

• Once the Meshing is done with the desired quality criteria, we need to ensure there should be no unnecessary rotating Trias elements in the model.
• And OFF elements should be zero in order to achieve quality.
• Trias elements can be adjusted using the Split & Swap options under Element Option, smooth the elements again and again till the flow is fine and accurate.
• In some cases, use the Paste option under the Grids bar to clean the Tria elements from the Edges.
• No kinks & raised edges are present in the model.

5. Generating Volume Mesh:

• After generating the Mesh, we need to define the Shell object to solid and then Mesh it.

• Tetra Rapid & Tetra FEM are mostly used in order to define the mesh under volume.
• Volume Property ID is defined separately with respect to the PSHELL ID’s.

• Switch on the Bounce & Volume option and OFF the Geometry & FE-Mode in order to view the Volume Mesh generated on the Rear-View Mirror surfaces.

• Both Shell & Solid are described in the PID manager.

RESULT:

A 3D Rear View Mirror is Meshed successfully, giving the quality criteria and performed the Meshing, Improving Mesh Quality using different tools with the help of ANSA and Volume Mesh is generated to define it as a solid object.

Google Drive Link: https://drive.google.com/file/d/1pOTFsCs0X8qPO1qkATauQYipEk5kUmos/view?usp=sharing

Learning Outcome:

• Meshing on Shell using Tetra & Tria Mesh with respect to the quality.
• Generating Volume Mesh under VMesh to generate a solid model.
• Analysing the volume generated for the Model.
• Zero OFF elements and Tet-Collapse errors.