Week 3

Aim

• To check the given model for geometrical errors and mesh with given quality criteiria.
• To assign thickness to the mesh model.

PROCEDURE

The model assigned was that of hood of a car which is a sheet metal component.

Step-1: to study the components of the model It basically had three components.

1. Frame
2. outer shell
3. inner shell

Step-2: To do the standard geometry clean-up.

• Ran pre-surface meshing geometry check and it had numerous amount of errors.
• It was fixed by auto-fix to save time.
• Measurements at various points were taken and the thickness of sheet was 0.75 mm for outer shell frame. It was 1.2 mm for the inner components.
• All the exterior surfaces were oriented properly.

Step-3: To create and prepare the mid-surface.

• The mid-surface created by offsetting the skin to middle of the surface.
• Middle surface was then joined together by topo.
• The mid-surface was then de-featured by joining the cons on the surface.
• Holes were checked to for even number of edges and were maked.
• The perimeter length was set to 5mm as required.
• Again measurements were taken around feature to make sure that the elements stick to required quality criteria.
• Bend on the outer shell was de-featured to eliminate the failure of elements for minimum length.
• Similarly corners in the frame structure midsurface was corrected to simplyfy the mesh.

Step-4: To type in the quality criteria and establish the mesh parameters.

• The quality criteria were keyed in.
• The mesh parameters was established, the average length was 5 mm, min-length-3mm,max-length-7 mm.
• The mesh chosen was a mix of trias and quads, becuase it yields better results.

Step-5 : Meshing and checking.

• To mesh the component mid-surface "best mesh" was used, as it yieled the better result.
• Large areas were topologically cut into smaller ones and individually meshed to get a better mesh flow. These cuts had to be Introduced at many place which were then removed without changing the established mesh flow.
• Mesh flow was checked to avoid elements failing the quality critieria many times. Troublesome mesh areas were reconstructed untill a satisfactory result was produced.
• Opposite trias were eliminated using "Split" and "Swap" after which the area was made proper again using "Smooth".
• The areas were symmetrical and hence could have copied the mesh. But since the associativty of the mesh with surface was not mentioned i went with manually meshing both the areas individually.

Step-6: Giving thickness to the mid-surface.

• Each of three mid-surfaces was individually selected and new shell property identity was created.
• Thickness correspondingly was given as 0.75 mm and 1.2 mm.
• Each mid-surface was then given a new material.

Conclusion

The model was Successfully meshed.

From this challenge i understood the basic problems that needs to be addressed by preprocessing, such as cleaning up the topology, defining mesh parametrs etc. most impportantly i was able to asses my knowledge and skill.

https://drive.google.com/file/d/1n9FGivX5C9pD9TnxxfLz-LvlfxvA_wAt/view?usp=sharing