Comparing different Mid-Surfacing & Meshing tools in ANSA for a Sheet Metal Component

ABSTRACT:

• By using CAE Pre-Processing Tool ANSA & to develop meshing for the given sheet metal component.
• Here different types of meshing were performed in order to compare and find the best suitable and efficient Meshing obtained from Batch Meshing with Skin Mid-surfacing, Auto-Mid generation & Meshing through Casting and Manual Mid-surfacing and Spot Meshing using off-set

METHODOLOGY:

1. Importing the CAD geometry in ANSA
2. Checking out the errors and Assigning Property ID (PID)
3. Assigning Quality Criteria & Mesh Parameters
4. Extracting Mid-Surface, Meshing and Improving Mesh Quality.

INTRODUCTION:

Keeping safety, strength and many design aspects, the sheet metal component has to undergo many conditions and final CAD outcome is considered for pre-processing in ANSA.

PROCEDURE:

1. Importing CAD Geometry in ANSA:

• After successfully importing the Bottle Cap CAD geometry we need to give the Target Length/ Average Length which is assigned as 3 under Mesh Mode<Perimeters<Length in order to gain the original geometrical structure of Bottle Cap.

2. Checking Out for Errors and Assigning Property ID (PID) for each Surface:

• We need to perform the geometry check under CHECKS Manager in order to see any geometrical problems of the model such as Unmeshed Macros, Unchecked Faces, Needle Faces, Collapsed Cons, Triple Cons, Overlaps and Cracks.
• ANSA detects some errors and we need to ensure that these need to fixed manually or by just running the automatic fix command and confirm that there are no geometry errors there in the model.

• For any component, we need to assign Property ID(PID)
• Make sure that the component is always Gray which indicates Positive in ANSA where yellow stands as Negative.
• Use the Orient option under Faces in Topo Mode to change the color of the model to Gray if it’s so. (Orient<Visible)
• The component has the uniform thickness as 1 mm across.

3.Assigning Quality Criteria & Mesh Parameters:

• The average length alters the shell element length of the component.
• Remaining values are assigned in the Quality Manager or just tapping the F11 key.
• Each element in the Mesh should qualify the Quality Criteria given.
• After assigning the values given for the quality check, we need to perform the topological clean up before meshing.

4.Extracting Mid-Surface, Meshing and Improving Mesh Quality:

• In order to Mesh the component, it needs to undergo mid-surfacing for all the surfaces involved as the component becomes a 2D object after extracting Mid-Surface and it will be ideally good for Meshing.
• There are different methods a CAE engineer can use for Mid-Surfacing the component and the best would be Mid-Surface<Skin, Casting or Offset<Faces under FACES option under Modules Buttons in Topo Mode.
• Always enable Cross Hatch while extracting Mid-surface as it helps to select a particular region and space so as to avoid unnecessary errors.

Meshing:

• After Topological Clean up, consider meshing each and every part separately
• One can use different methods in order the Mesh the surfaces, I used the Best Meshing option under Mesh Generation in Mesh Modules Buttons.
• Best Mesh ensure the user a good Mesh flow across the part and ANSA provides a decent outcome.
• Once the Meshing is done, try to reconstruct the Mesh generated and Smooth it for enhancing the Mesh.

Improving Mesh Quality:

• Once the Meshing is done with the desired quality criteria, we need to ensure there should be no unnecessary rotating Trias or Quad elements in the model.
• No Tria elements on the edges
• And OFF elements should be zero in order to achieve quality.
• Trias and Quad elements can be adjusted using the Split & Swap options under Element Option, smooth the elements again and again till the flow is fine and accurate.
• In some cases, use the Paste option under the Grids bar to clean the Tria and Quad elements from the Edges.

A. Skin Mid-Surface extraction & Batch Meshing:

Mid-Surface extracted by using Skin Option:

Running the Batch Mesh:

Mesh Results using Skin & Batch Mesh Option:

B. Mid-Surface extraction & Meshing using Casting:

Improper capturing of Mid while by using Casting option:

Improving Mesh Quality using different tools under Mesh Module:

Mesh Results using Casting option:

C. Mid-Surface Extraction using OFF-Set & Manual Meshing using Spot Mesh:

Improving the CAD geometry:

• Make sure that the holes are parallelly adjusted to the adjacent perimeter.

Meshing the component using spot Mesh option and improving the mesh quality:

Mesh Results using Manual OFF-Set Method & Manual Mesh generation:

RESULT:

• A 3D Sheet Metal component is Meshed successfully converting into the 2D surface by extracting its Mid-Surface giving the quality criteria and performed the Meshing, Improving Mesh Quality using different tools with the help of ANSA.
• I found that under Auto Mid generation, Skin Mid-surfacing & Batch Meshing gave good results than Casting Method.
• Though ANSA gave good results in the Skin method using Batch Mesh, equal results were obtained Manually through the OFF Set method and feature capturing is much accurate in the Manual Method.

Learning Outcome:

• Examined the different Mesh options and figured out the significance of quality mesh for any component.
• Time constraint while using different types of Mid-Extraction and Meshing Methods.
• Improving Mesh quality and solving OFF elements.

Google Drive Link: https://drive.google.com/drive/folders/17wm8NmbgkeCtMq9KetZgqAS3vtN1UJWv?usp=sharing