Week 4 - 2D Meshing for Sheet Metal

AIM: The main aim of this challenge is to mesh the given ccb assembly as per below element quality criteria.

S.no	Element Quality Criteria	Value
1	Target/Average length	5
2	Minimum Length	3
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.

• After opening the file, topo operation (TOPO-->MODULE-->FACES-->TOPO) was performed to convert the unstitched surfaces (single cons) to stitched surfaces (double cons).

 

3. After performing the topo operation, geometry check (TOOLS-->CHECK--> GEOMETRY) was done in order to remove geometrical errors.
4. 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. Totally there are 34 components in the given assembly, and mid surface is extracted for all the 34 components individually using skin method.

8. Mid surface can be extracted by using mid surface (skin method) method (TOPO MODULE --> FACES--> MID SURFACE-->SKIN).

9. Mid surface is automatically extracted exactly at an offset distance of half of the thickness of that particular parent geometry.

10. In the skin method, the thickness for the component will be automatically assigned to particular component once the mid surface is generated.

 

11. After mid surface generation, again geometry check has been done and all the errors in mid surface were fixed.

12. Before meshing the component, all the macros and perimeters of the given assembly were set to target length using length option in perimeters tab of mesh module. (MESH MODULE à PERIMETERSà LENGTH). Element Quality criteria was also set according to the given question.

13. Meshing is done for each component separately using best mesh and reconstruction options. For obtaining good mesh flow several options like swap, split, paste, collapse& join commands were used.

 CONCLUSIONS:

1. Learnt about geometry clean up and extracting the mid surface using skin 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 2.0%.