Week 3 - 2D meshing for sheet metal

Procedure for meshing the given model is as follows,

1. Clean up the CAD model using Topology module and remove the inconsistence in entities.

2. Switch on to entity mode, isolate each part & check for errors with the help of Boolean operations.

3. Define material as given in the statement or standard material will be steel as default.

4. Check CAD topologies using checks manager, check parameters such as triple con, single con, etc.

5. Check the model for geometric errors. If the executed result passes, then the CAD model is free from errors and no need to clean up the geometry.

6. If there are any errors in geometry, auto-fix whichever is possible. Errors which cannot be auto fixed, right click on the error & select show only. The actual error will be displayed which has to be fixed. Similarly perform check geometry until the result passes completely.

7. Ensure the thickness of the model is uniform using measure option.

8. Check the features for proper definition using Fine option in Auxiliaries module. Refine the feature to check the smoothness at the edges, so that the actual view of the feature will be displayed.

9. Maintain positive orientation to the model by selecting orient option in Faces module.

10. Generate mid surface of the given module using Offset -> Faces. Activate the cross hatch lines and select the face to be offset by clicking the centre of cross hatch in that particular face. After selecting the face click on middle mouse button to confirm the action. Enter the offset value equal to half of the model thickness. Depending upon the arrow mark, enter positive or negative sign for the offset value.

11. Make visible only the mid surface & lock the view. Check for unnecessary single Cons and perform a topology. Once all the surfaces are associated with neighbouring surface, orient the mid surface to meet uniformity. Assign a separate property for the mid surface by set PID option. Select the complete mid surface and perform action, enter the thickness equal to model thickness and OK. Cross check the property assigned by switching to PID mode. At the end, perform check geometry and de-select single Con option and execute.

12. Switch to mesh module and check for colour representation. Measure the element length by measure option. As per the requirement, assign element length by length -> Perimeters. Enter the element length value and perform the action.

13. Check critical areas or small areas for element length. If the element length is less than prescribed length, modify the element without affecting the actual geometry.

14. Check for holes on the faces. If the holes are represented by diamond shape, select slide option in perimeter and make the node parallel to the nearest perimeter by sliding in any direction. Later mark the nodes. Similarly perform same action for all holes. Check number of edges on the hole by number option in perimeter. Maintain even number of edges for better results.

15. Check for node length at critical or small places. If the length does not pass the criteria, de-feature the model without compromising any fillet or critical CAD geometry.

16. Set up the quality criteria by pressing F11 key. Based on the quality requirement, key in the values and range.

17. Switch over to mesh module. Start meshing the most critical face which has got features and holes. Select best mesh option and select the area to be meshed and middle mouse click to perform action. Turn on hidden mode and check for quality of mesh. If there are any errors in quality of mesh, use mesh improvement tools like Reconstruct, Smooth, Fix Quality, improve, etc. to eliminate the quality errors.

18. After meshing the feature, take up the faces which have holes and slots. Perform best mesh on the face. Check for Trias originating from the hole and hitting the perimeters. Such Trias should be eliminated to have a better quality of mesh.

19. Faces can be subdivided into areas and meshed separately. By following this method, Trias element can be avoided as much as possible. Remove the subdivided perimeter or line by join option. To maintain the same mesh flow, select Keep in mesh option list instead of reconstruct. Smooth the complete face after removing the cuts.

20. Similarly perform meshing for all the surfaces. Hide all the meshed area and check if there are any faces to be meshed. Once the model is meshed completely, at the surface where there are features has to be addressed and paste the connecting nodes manually using paste option in Grids.