Week 3 - 2D meshing for Sheet metal

AIM: The main aim of this challenge is to mesh the given car hood inner panel as per below element quality criteria.

S.no	Element 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	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120
12	Tria Percentage	15

OBJECTIVE: The objectives of this challenge are as follows:

1. To perform geometry clean up and generating mid surface for the given component.
2. To mesh the given component with less tria concentration and good mesh flow.
3. Finally all the elements should pass for given element quality criteria.

PROCEDURE:

• 
  The CAD file in ANSA can be opened by selecting the open option in file tab.

2. After opening the file, topo operation (TOPO MODULEàFACESàTOPO) was performed to convert the unstitched surfaces (single cons) to stitched surfaces (double cons).

3. After performing the topo operation, geometry check (TOOLSàCHECKà GEOMETRY) was done in order to remove geometrical errors.

• 
  Geometry check was done for unchecked faces, collapsed cons, triple cons, needle faces, overlap faces, cracks & single cons.

5. Some of the errors can be fixed automatically by using fix option and the errors that cannot be fixed automatically needs human attention and those errors should be solved manually.

6. Once all the errors are rectified, we are good to go for extracting mid surface of the given component.

7. Mid surface can be extracted by using offset method (TOPO MODULE à FACESà OFFSET).

8. Mid surface is extracted exactly at an offset distance of 0.375mm which is exactly half of the thickness of the parent geometry.

9. For the obtained mid surface, a new PID & thickness value are assigned.

10. Since the given component is symmetrical component, half part of the component is deleted carefully and meshing operation is performed by dividing the component into several macro areas.

11. After meshing half the component, the symmetry operation (TRANSFORMà COPYàSELECT ENTITIESà SYMMETRYà DEFAULT SYMMETRY PLANE) is used for mirroring the component along with the mesh.

• 
  After performing symmetry operation, where ever the surfaces are not properly stitched, there topo operations and cut operations were performed to stitch the surfaces.

• 
  Finally after finishing the mesh thickness value of 0.75mm is assigned to the component in property option.

CONCLUSIONS:

1. Learnt about geometry clean up and extracting the mid surface using manual offset method and automatic mid surface options.
2. Learnt about how to mesh a component for a given quality element criteria.

RESULTS:

Geometry cleanup, mid surface extraction and meshing of the given component was done successfully. Trias concentration was limited to less than 1.5%.