Week 6-Meshing of Hood Challenge

Meshing of Hood

Aim:

To extract mid-surface and generate mesh on Hood using Hyper mesh.

Given model:

Steps Involved:

1. Importing geometry and cleanup.

2. Extracting Mid-surface and assigning properties.

3. Meshing the surface with in the given quality criteria.

Quality criteria:

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
11	Tria %	10
12	Element size	5

Procedure:

Meshing of Hood: Here we will see the Meshing of different parts of Hood.

Hood consists four different components as below:

• Inner Extract

• Outer Extract

• Hinge Reinforcement Extract

• Latch Reinforcement Extract

Step 1: Importing geometry and cleanup:

• To import the geometry, go to file » Import » select the file » Import.

• After importing the geometry, the geometry is checked for any missing surfaces or triple cons. If there are no errors present in the geometry then the geometry is ready for the mid-surface extraction.

Step 2: Extracting mid-surface and assigning properties:

• Mid-surface can be extracted by any of the 4 methods below.

1. Offset + plane + sweep.

2. Offset + plane.

3. Skin Offset.

• To extract the mid-surface, go to geom » mid-surface » select any extraction option » select the surface » extract. In this challenge offset + plane + sweep is used.

• After extracting the mid-surface, it is checked for any geometrical errors like needle faces, missing surfaces and triple cons. If any of the errors present then it should be rectified immediately.

• Now the properties like thickness, material etc. need to be assigned to the mid-surface. To assign the properties, select model in database and right click and choose create and then property.

• Now all the properties are entered in the property tab and the properties are assigned to the respective mid-surfaces.

• To assign the properties to mid-surface, right click on the mid-surface and then select assign and select the respective properties which needs to be assigned.

Step 3: Generating mesh within the given quality criteria:

• Before generating mesh, the geometry is cut into smaller rectangles for good mesh flow.

• To generate mesh, go to 2D » automesh » select the surface » mesh. To edit the mesh for proper flow, the elements are selected and meshed again.

• If any elements are failing for quality then cleanup tools option which is present in quality index can be used.

Now we will see all the four components one by one

Inner Extract:

• There are four different components in the file when we import it.

• First of all make sure that only "Inner Extract" component is active.

• Delete all solids from the component.

• Create Mid surface for only Inner Extract by selecting particular surfaces.

• Since this component is axis symmetric, we can cut it in to half and mesh it.

• So we can mesh that at the last.

• As shown in above image, split the midsurface and keep half of that for meshing.

• Complete the mesh of the hald portion of the Inner Extract as shown in above image.

• Now we can reflect the elements on the other side and complete the total mesh on the component.

• As shown in above image, elements are reflected on the other side.

• Make sure that elements are in proper connectivity.

• So, create equivalence between the elements which are in symmetric line and make them connected as shown in above image.

• Thus we can complete the Meshing process for "Inner Extract" component.

Outer extract:

• As shown in above image, Create Midsurface after deleting solids from Outer Extract as shown in below image.

• As shown in above image, the hemming portion of the component is very thin.

• So, after creating midsurface, we can toggle the extra edges and split the component from the curvature area as shown in above image and easily create mesh without minimum length element.

• Start with the curved or radius portion to avoid minimum length elements and step by step create mesh as shown in above image.

• We can further divide the curved portion marked in above image and create better quality elements in that region.

• Reflect the Mesh and create equivalence in the symmetry region.

• Thus we can complete the Mesh of "Outer Extract" component with better mesh flow.

Latch_reinforcement_extract:

• Delete solids and create Mid surface for Latch Reinforcement Extract component.

• Do necessary cleanup and toggle extra edges.

• Keep the mesh flow as per geometry.

• Avoid tria elements at the free edges.

• As shown in above image, create mesh at the centre first and then proceed further for good mesh and complete the entire mesh for Latch Reinforcement extract.

hinge_reinforcement_extract:

• Here there are two components in Hinge Reinforcement Extract.

• So, delete solids and create midsurface for part.

• As shown in above image, avoid creating washer surface for the holes for better mesh arrangement.

• Toggle the edges where minimum length element can occur.

• As shown in above image, mesh is created at the inner most area where less free edges are there.

• Then followed by them, rest of the part is meshed.

• Thus we can apply mesh on both the parts of Hinge Reinforcement Extract.

Thickness:

• After meshing all the component, apply 2 units of thickness to the property.
• after applying thickness, Complete the meshed Hood will look as shown above.

Conclusion:

For the given Hood panel mid-surface is extracted and mesh with is generated using the given quality criterias.