Week - 5 - 2D meshing for Plastic components

2D Meshing for the plastic components

Aim:

For the given (Bottle Cap) CAD model geometrical cleanup, mid-surfacing and meshing are performed for the given quality criteria.

Objective:

• Proper geometry cleanups (Ease access of mid-surfacing).
• Manual mid Surfacing
• Mesh Flow correction by using PID Region.
• Meshing the model as per the given QC.

Procedure:

1) Importing the (IGS file) model into the ANSA.

2) To improve edges and curves feature qualities, in classic mesh LENGTH---Perimeters and Macros are adjusted to 1 to get the good finish of the solid model.

3) Topo command is used for the stitching of curves with their neighbouring edges. It will turn red (Single cons) to yellow (Connected cons-2), and the orient command is performed for the proper face alignments.

4) Geometry checks are done, which corrected automatic FIX as well as manually. This geometry had many errors cleaning up took some time. Corrections are done for the entire geometry without any errors because with some errors auto mid-surfacing and meshing cannot be done in proper manner.

5) After correcting every error, the given model can be investigated whether sheet metal or plastic. It is determined as plastic, containing various thicknesses throughout the model.

6) Quality criteria file is saved as per the given model.

7) As this model is identified as a single large component auto mid-meshing (CASTING/EXTRUSION) process can be done to save the project’s time period. But still, if the errors are too high it is recommended for the manual mid-surfacing and manual meshing method.

8) After the process is completed mid-meshing correction can be done as it has too many off elements and trias are present, so the manual method is recommended.

9) For the manual approach, the model has to be simplified for easy extraction of the mid-surface of the model.

10) With the different thicknesses manual mid-surfacing operation is better to be carried out from bottom to top of the model with the appropriate command like FACES---offset, middle, extend, intersect etc.

11) During extraction also proper geometrical cleanups are focused on minimizing the elemental errors.

12) Ribs extractions are performed well with the FACES—Middle command.

13) Symmetry can be performed whenever before or after meshing, to save time it’s recommended for after meshing. Here symmetry is done before meshing to see the entire mid-surface of the geometry properly.

14) Two COG points are made to perform the circular pattern of the inner ribs. After extracting the one rib all the other ribs are replicated by polar or circular patterns by using the COPY ENTITIES—Rotate command.

15) After extracting all the mid-surface manually (which takes a very long time) meshing can be done with the BEST mesh command, the regular mesh flow criteria are followed and other off elements are removed. But in this model due to complex surfacing still OFF elements are present in low numbers.

16) OFF elements and proper mesh flow are to be generated by using proper areas with INOT command.

17) Commands like SPLIT, SWAP, JOIN, PASTE are used to correct the mesh flow manually for the optimized quality.

(Paste option in GRIDS)

18) Commands like SMOOTH, RECONSTRUCT, RESHAPE, IMPROVE, and OPTIMISE are used to correct the elemental errors for good flow with the mesh.

19) Final checks are done with mesh flow, OFF elements status etc.

Course Outcome

• Large geometry cleanups.
• Complex manual mid-surfacing.
• PID region and INOT commands for the mesh flow corrections.
• Understands the different concepts about plastic and sheet metal models.

Results:

The given (Bottle Cap) CAD model geometrical cleanup, mid-surfacing and meshing are performed with average flow criteria as per the given quality criteria.