Week - 4 - 2D meshing for Plastic components

Report on 2D meshing for Plastic components

Aim:

• To extract the mid surface from the given CAD model of Plastic component(Bottle Cap) and mesh the extracted mid surface.

Software Used: ANSA

Given Model of Plastic Component(Bottle Cap)

Pre-Processing:

• Pre-processing involves steps .They are:

1. Import the CAD
2. Geometry clean up
3. Skin/Mid Surface Generation
4. Shell/Solid Meshing
5. Element Quality Check
6. Mesh Improvement
7. Boundary Conditions
8. Apply load
9. Export Input File

Step - 1:

• Cad file is imported in ANSA software.

Step - 2:

• The imported CAD geometry has few errors due to transfer of the CAD model into ANSA.
• Perform geometry check, so that we can find errors such as unchecked faces,needle faces and cracked faces.
• Switch to Classic Topo module.
• we can fix these issues using Topo commands such as insert,delete,paste,release topo,cut,new,fine...
• Following are the errors in the geometry.

Before Fixing:

After Fixing

Step - 3: Mid-Surface Extraction

• After cleaning the geometry of Bottle Cap, extract the mid surface.
• As it is a plastic component, the thickness is not the same throughout the model.Split the surface into multiple surfaces.
• So that it is easy to extract. The model is a symmetry component , After meshing we can symmetry it.
• Mid - Surface is extracted for meshing the model.
• Mid - surface is extracted from the Plastic component using offset and middle command.

Step - 4: Meshing

• Now switch to classic mesh module.
• Meshing of the model is generated using Best command in mesh generation group.
• As Bottle Cap is the complex model mesh should be generated layer-by-layer.
• At complex areas , do not directly mesh, as it makes the mesh clumsy. Instead make some cuts on the mid-surface then mesh.

Step - 5: Element Quality Criteria

• After Meshing , Set the element quality criteria values.
• If the element fails the quality criteria parameters, the elements are indicated with different colour codings.
• Where the quality criteria is failed, there is a possibility of deformation
• Adjust the mesh to pass the element quality.

Step - 6: Mesh Improvement

• After meshing the surface, the mesh has only two types of elements. They are Quad, Tria.
• The mesh should be a smooth flow.
• Mesh can be improved by smooth, reconstruct, improve, Transform...
• There are few Tria rules to be followed for good mesh. They are:

1. Opposite trias should be avoided.
2. No trias should be perpendicular to each other.
3. No trias should be back to back.
4. No trias should be on the edge of the geometry.
5. No trias should be near to the holes.
6. No trias should be on the features(Fillets)
7. Less tria concentration

Before Fixing:

After Fixing:

• And assign property for it.

• After performing “Draw shell as solid” in Quality criteria > Presentation parameters.

Conclusion:

• The geometry is cleaned and mid-surface is extracted from the geometry.
• Thickness and material of the model is assigned to the parent geometry.
• The mid-surface is meshed with the required quality criteria.

NOTE:

• As the size zip file is more than 20MB, The file is unable to upload.
• The google drive link for Zip file of Meshing of Bottle Cap is :

https://drive.google.com/file/d/1GVsdWgVcT8pPIeFK2qnm01dq770oXpFe/view?usp=sharing .