Week 6-Meshing of Hood Challenge

AIM: - To extract the mid surface and generate the mesh on the hood model.

OBJECTIVES:

• For the given model (Car Hood) mid-surface is done separately for each component and then meshed.
• Meshing and Quality Criteria values should be considered during the process.

QUESTION:

Follow the below-mentioned quality criteria, mesh the component given below and assign thickness:

Target Element Length = 5 Units

S. No	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2 Units
6	Max. Length	8 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

(Note: Make sure that all the mid-surface is done separately for each component and then meshed. Attach the Hypermesh model files (.hm) with the challenge)

You will have to submit a detailed report describing whatever you have performed in the challenge. You will be graded for the report as well.

PROCEDURE: -

The given model is the Car ‘HOOD’ We need to create mid-surfaces separately for each component and then mesh.

Step 1- Importing and Visualizing the Model

• Import the given step file Model as geometry
• Visualize the model if it has any deformities in its surface or free edges, which can be visualized in wireframe

Step 2- Geometry Cleanup

• Initially we need delete the solid from the model, which also benefits in less time consumption for computing in Hypermesh.
• Then check the thickness of all the components.
• To check the thickness of the component, we go to the distance option in Geom (F4) and select the two points option, then we select any two points from the component and find the thickness of the components.

Step 3- Extracting Mid-Surface

• Extract the mid-surface using the auto mid-surface option
• Goto > Midsurface in Geom tab, then in extracting option select the skin offset option, then in the auto extraction option we select the surf - displayed, and click the extract option.
• After extracting the mid-surface for all the components of the hood, we need to rearrange/toggle the construction lines so that to get a good mesh flow.
• We also have to delete the unusual points on the mid-surface which can disturb the mesh flow.
• At the place of fillets and curves, we need to properly rearrange the construction lines, so as the meshing will follow the original geometry of the model.
• We should also delete/toggle the construction lines that are too close and can cause minimum element length failure.
• We also create the washer split at the holes, so can obtain a proper mesh flow.

Mid surface is extracted for all the components as shown below

Latch mid-surface

Hinge Mid-surface

Inner panel mid-surface

Outer panel mid-surface

Step 4- Generate Mesh & Optimize the Mesh quality

• After extracting the mid-surface and do all the processes required for the mesh, we need to provide all the required criteria for the meshing.
• The meshing will automatically generate according to the criteria provided.

• Auto meshing is done, with the element size to be 5 and mesh type-mixed.

• After meshing, there are so many back-to-back trias and quad elements that will be formed, So, we need to optimize the quality of the element.

Quality Index just after meshing

Splitting

• To optimize the element quality, we can use tools as element optimize, drag tria, smooth, edit-element (split/combine/create).

• To optimize the elements, we can use the Rebuild option and also remesh the element of a particular place.
• This will remove all the element failure from the mesh, as it is necessary to have a proper mesh for the analysis, if our mesh flow or mesh element is not properly made, we cannot calculate the accurate analysis.

Quality Index after performing all the operations mentioned above

Meshing is done with given criteria parameters for all the components as shown below

Latch mesh

Hinge mesh

Inner panel mesh

Outer panel mesh

Assigning Material to the Created Mid-Surfaces:

To assign material, right click > Create > material

Assigning Property to the Created Mid-Surfaces:

To assign property, right click > Create > property

RESULTS:

Final Meshed and Assembled given car Hood model

Conclusion:

Hence, Mid-surface is done separately for each component and then meshed for the given model (Car Hood). Given Meshing and Quality Criteria values are considered during the process. Learned how to remesh, rebuild to optimize the element quality, learned how to efficiently use the cleanup tools and worked on Quality indel tools.