Week 3 - 2D meshing for sheet metal

OBJECTIVE

For the given hood model, take mid surface for all components after checking the geometrical errors and mesh the mid surface with given element quality criteria.

SL NO	QUALITY CRITERIA	VALUE
1	Target/ Average length	5
2	Minimum Length	2
3	Maximum length	7
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120
12	Tria Percentage	15

PROCEDURE

Step 1: Topological clean up and mid surface extraction

• Go to property manager.Select one of the body PIDs.
• Click on geometry checks.Select single cons, triple cons, needle faces,cracks,overlapped surfaces.
• Right click on property manager and click fix.
• Measure the thickness of part and extract mid surface using offset method.
• Assign PID to the generated mid surface and smooth the edges and holes.
• Do the above procedures for all PIDs

Step 2: Surface Meshing

• Select one of the Mid surface.
• Give perimeter as 5 mm
• Go to mesh parameters and select mixed,give target length, minimum length and maximum length as 5mm,2mm and 7mm.
• Give the quality criteria as per the question

• Measure the distance between the nodes in some area where quality may fail. If any nodes are there remove or create some cuts.
• Mesh the surfaces with minimum number pf trias. Eliminate rotational quads , off elements and opoosite trias using smooth,reconstruct,split, swap, join options.
• Mesh the other mid surfces as per the above quality criteria.
• In case of hood outer body and structure, both are symmetric bout the mid plane.So delete the one of the halfs.
• Mesh the half and copy the meshed surface using transform - copy- mirror 3 point plane option.

LEARNING OUTCOMES

• Understood how to extract mid surface using offset method and mid surface method.
• Understood how to remove unwanter hot points, surfaces and how to create new surface.
• Understood how to mesh the given surface as per the quality criteria.
• Understood various methods to eliminate off elements,pposite trias and rotational quads.

RESULT

For the given hood model, took mid surface for all components after checking the geometrical errors and meshed the mid surface with given element quality criteria.

CONCLUSIONS

• Two methods are there for creating mid surface. Offset method and mid surface method.But mid surface option automatically deletes the orginal surfaces.
• At the coverging areas, smaller areas number of trais are more.
• Proper cuts in the surfaces creates smooth mesh flow.