Week- 5 - Solid meshing

Week – 5 Solid Meshing – Rear-view mirror

Objective –

To check for the geometrical errors for the given component and match with the given element quality criteria. Use Tetra elements to model the component and finally create volume mesh for the given component.

The quality criteria to be followed –

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

Methodology –

• Import Geometry
• Topological clean-up
• Take measurement
• Quality criteria setup
• 2D Meshing using Tetra and Ortho tetra mesh
• Mesh improvement
• Define Volume for each component
• Remesh the volume
• Set quality for solid – Tet collapse – 0.2
• Mesh improvement.

Introduction to rear-view mirror –

A rear-view mirror is a flat mirror in automobiles and other vehicles, designed to allow the driver to see rearward through the vehicle's rear windshield.

In cars, the rear-view mirror is usually affixed to the top of the windshield on a double-swivel mount allowing it to be adjusted to suit the height and viewing angle of any driver and to swing harmlessly out of the way if impacted by a vehicle occupant in a collision.

Procedure –

First import the CAD model given in the challenge to ANSA, which is a rear-view mirror.

After importing the CAD model, perform topo option on the model. Now the topo operation is done at all the free surfaces as shown in below figure. After that please check for orientation of the model.

For better visualization of curves and edges and also to refine the cad geometry, we go to mesh module and go to the length option present in the section of perimeter. And provide parameter length and macro length as 1mm.

Now we check for the geometric errors using the check geometry option present in the tools option as shown in the image given below.

If there are any errors, please select all the errors at once and perform auto fix. Still if some of the errors are left use the manual method to fix it. All the errors are fixed as shown in the figure below.

Now, before proceeding with the 2D meshing of the model, please check the property and name parts. 1. Socket, 2. Mirror, 3. Holder, 4. Support. As shown in the figure below.

Part – 1 Socket

Part – 2 Mirror

Part -3 Holder

Part -4 Support

As per the challenge please set the mesh parameters and quality criteria as mentioned.

Once the quality criteria and mesh parameter are set, we can proceed with the meshing.

In mesh generation select spot mesh and use ortho tria or tria mesh option and mesh the model. As the 2D meshing is complete for all the models as shown in the figure below we can proceed with volumetric mesh.

Volume Mesh –

Set the quality parameter for the volumetric mesh as mentioned in the challenge for Tet collapse of 0.2 mm. Now we must define the volume before we proceed for volumetric mashing of the component. We define the volume for the component using the define option present in volume section of the volume mesh model.

To create the volume tetra mesh for that component, select unstructured mesh module and click meshing option like Tetra rapid or Tetra FEM. The other way to do it is in the list option right click on the volume and select remesh option for tetra mesh as shown in the figure below.

Similarly, the volume Tetra mesh is generated for all other components and the off elements are eliminated by using MV free option and the volume Tetra mass of the rear view mirror is generated as shown below.

Learning Outcomes –

• Learned to mesh solid plastic component with non-uniform thickness.
• Learned to define the volume for the component and use ortho tetra option for volumetric meshing. Clearing errors such as kink, dip and tet collapse elements.

Conclusion –

As per the challenge for the given rear-view mirror of an automotive vehicle, geometrical errors was checked and meshed with elements type as ortho tria and tria as per quality criteria. Volumetric meshing was done for the component as the thickness was not uniform to generate a mid-surface. All the off elements was cleaned in the model as per requirement.