• to check for geometrical errors
• take the mid surface.
• mesh the Surfaces with the given 2D element Quality criteria.
• assign thickness.

Abstract

In this project, the instrument panel of the car dashboard is taken for the pre-processing stage of CAE. The pre-processing of this model is done using BETA-CAE-ANSA software. The mid-surface extraction and shell meshing are mainly demonstrated here in this project. Also, the good practices to be followed during shell meshing are discussed here.

Methodology:

The methodology for the given element is as foll

Quality criteria

S.No	Quality Criteria	Value
1	Target/Average length	4
2	Minimum Length	2
3	Maximum Length	6
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
10	Tria Percentage	15

Procedure

1. Import geometry:-

First of all, the model was created by a design engineer based on requirements but that engineer is not understand about this model is good or bad then ANSA software is required the check the quality criteria.

First of all import a file of the model in ANSA software.

FILE > OPEN > (MODEL)

We can see there are many single cons and faces are not stitched properly.

2. Perform TOPO on it, as the model is too distorted after importing from different software.

Classic TOPO > Faces > TOPO

3. Geometry Check and execute

4. There are almost 791 errors. Select all the errors and perform

5. Now we can see some of the errors have been fixed by ANSA. The errors have been reduced to 208.

6. Select the remaining errors and click show all.

7. Now go to individual errors and fix them.

8. Improper surface

Select Neighb 1^st level to see the nearby surfaces.

Delete the improper surface, Classic Topo > Faces > Delete

  

Create new surface with Classic Topo > Faces > New

9. Go for other errors also and fix them.

Delete the improper surface Classic Topo > Faces > Delete

Create a new surface with Classic Topo > Faces > New

10. Clean the geometry using the checks manager. Enable unchecked faces, collapsed cons, triple cons, needle faces, overlapped faces, cracks, and single cons. Clear all these issues until no error is found. One can use fix option in ANSA to clear all the errors automatically. However, sometimes manual intervention is required for fixing some errors.

11. Quality criteria and parameters:

12. Generate mid-mesh by casting method

To give perimeters and macros length on the components,

Go to (Mesh Module >Perimeters>Length)

Similarly, do the same thing for the macros also.

Why to Extract Mid Surface ?

Before extracting the mid surface for every component,We should measure the thickness of the component and then we have to proceed to extract the mid surface.

If the component thickness is less than 6mm then we will come to know it is a sheet metal component.

Below image represent casting process. Once casting is done mid-mesh are hidden in present geometry to visible mid-mesh by using Faces off to switch to micro option and open align manager by 

Manual midsurfacing

Switch Topo to Classic mesh to show the mesh.

The below image is after the completion is done.

Below image result is appropriate and achieving 1% off element and 5.68% of Trias.

• Parameter-

• Faces - (Red colour)
• Offset - (Green)
• Sharp - (Dark pink)

Empty - this will not define any surface and parameter and it should be eliminated by defining the surface properly.

• View Empty by (Select all empty>right click of mouse>Visibility>Show only)

• Here is an empty surface as below image.
• To fix this kind of error by using paste option (Classic mesh>Grid>Paste>Select one node and second node>middle click of mouse)

 mesh>Macros>Join

• To create the surface first by using (Topo > Curve > Create)
• To create the surface by using (Classic > Shell mesh > Fill > Select the curve/Parameter > middle click of mouse)
• Then Select method by changing from Draft to coons > OK
•  Now create a second surface, first Go to 

(Classic>Shell mesh >Project>select the Shells by macro >Next)

• Select entity to project Project Perimeters > Finish.

As below image, this area is not proper and part missing so first resolve this area by following stages. First, toggle the unwanted line.

• After toggle, the line Surface looks like the below image.
• Select red surface. 
• Select the blue surface.
• The surface is Flat as shown below image.
• Reconstruct this area.
• o create the surface first by using (Topo > Curve > Create)
• Project the curve line in the base surface (Classic>Shell mesh >Project>select the Shells by macro >Next)

To create the surface by using (Classic > Shell mesh > Fill > Select the curve/Parameter > middle click of the mouse)

To Attachment this surface to the base surface by using (Classic mesh > Grid > Paste > Select one node and second node > middle click of the mouse

• The final image of this surface and element some trias as much as can.
• Doing all the operation below is the final image.

Final Image with Mid-mesh

In Align Mode

Applying thickness

Quality criteria > Presentation parameters > Draw shell as solid

Learning outcomes:

In this project I learned the following things:

to perform geometry clean-up for complex geometry.

• to create the surface while using the casting method.
• to achieve less Tria concentration with proper mesh flow.
• to clear failing elements from quality.

Conclusion

• In this project, I have generated mesh using casting options in ANSA.
• Performed de-feature, line adjustments in some areas, topological clean-
• Understood Transparency mode and the concepts related to generating mid-surface for different features.
• Able to achieve better mesh flow using smooth, reconstruct, swap, pas
• Successfully generated mid-surface and meshed whole Instrument panel using ANSA.