WEEK:3 - 2D MESHING FOR SHEET METAL

AIM:

For the given Hood model, Take the mid surface for all the components after checking the geometrical errors and mesh the mid surface with the given element Quality criteria.

S.No	Quality Criteria	Value
1	Target/Average length	5
2	Minimum Length	2
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
10	Tria Percentage	15

INTRODUCTION:

The car's hood is given for the operation. The car's hood is simply a sheet metal component. The geometry of this hood model is taken into consideration in the ANSA interface inorder to establish proper mesh andd check quality criterias.The car's hood is composed of 4 different parts.

1. Outer panel
2. Inner panel
3. Latch
4. Hinges

METHODOLOGY:

1.Import:-

1. File > Open > Choose the File and hit on open.

2.Cons resolution by Length option in Mesh module.

1. If the imported file is an .igs file it doesn’t have any connectivity between the Surfaces.
2. To get the connectivity between the surfaces we have to use the Topo option.(TOPO Module> Faces > Topo)
3. We have to Orient the Surfaces to make sure all the surfaces are in one normal direction.(TOPO Module> Faces > Orient)

3.Checking the geometrical errors.

4.Clearing the geometry errors.

5.Check the thickness of the components.

1. If the thickness is less than 5 or 6mm then we have to extract the midsurface.
2. If the thickness is more than 5 or 6mm then no need to extract the midsurface.

6. Creating the midsurface for a sheet metal Component.

1. If the components have the uniform thickness then we will be using the Skin or Offset options to extract the midsurface.
2. If we are using the skin method make sure that unchecking of Delete original surfaces in the options list.
3. If we are using the Offset option, we will be using the feature selection to get the mid surface in an easier manner. While providing the offset value we have to make a change in the options list from use existing to auto create for the property.

7.Providing the Target element length by using the length option in the mesh module.

8.Providing the Mesh Parameters and Quality criteria to the models.

9.Cleaning the Midsurface extracted.

1. If there are any unnecessary hotpoints we will be using the Delete option in Hotpoints group to avoid or we can use the insert option with right mouse click.
2. If there are any construction lines which will affect the mesh flow we will avoid them.
3. If there are any two feature lines which are very near to each other and the distance between them is less than your minimum then you will be suppressing any one of the line.
4. Feature Line:- We call a double con as a feature line when the surface after that double has significance change(Flat surface may be attached to a curved surface or viceversa) in the geometry.

10.Spliting the surface in the small square-like structures.

11.Generating the Mesh.

12.Clear the elements which are failing for the quality criteria.

13.Assign the proper orientation to the elements.

14. Assign the proper thickness for the newly created midsurface.

15. Release the FE from the Geometry.

PROCEDURES:

1. The hood model which is the CAD geometry is imported to ANSA workspace. The model includes 4 components.

• Outer Extract
• Inner Extract
• Hinge
• Latch

2. Here, we will working on inner panel which is a symmetric in shape .So prior to that we can delete one of the symmetric face and work on the other part.Please refer the image below .

4 . Next step need to be done with cons resolutions (classic mesh>length>select all perimeters)

The length can be given as mention in challenge .So,then the mention length will be followed in between the cons.

5. Next the model need to be orientated means that the model should be follow the similar orientation over the model.

6.After the orientation of the model, next we need to go with the geometry check.

NOTE : parent element should be under the geometry check .

next the errors need to be fix and execute the model .

7.Next , we need to find the thickness where we can find uniform thickness for the sheet metal component.

8. After the geometry check , then we will go to extract the surface .

Two methods can be followed : manual or automatic .

we will be using the manual option as OFFSET>Feature>selecting the surface to be extracted.

Here , the surface has been extracted but the marked surface is an unsymmetric geometry .So, we didnt cut the geometry.

9.Next i have mentioned at the top of this project script with the quality criteria and mesh parameters.

Here , we need to enter the values and save it for further use to import whenever you want .

10.Cleaning the Midsurface extracted.

1. If there are any unnecessary hotpoints we will be using the Delete option in Hotpoints group to avoid or we can use the insert option with right mouse click.
2. If there are any construction lines which will affect the mesh flow we will avoid them.
3. If there are any two feature lines which are very near to each other and the distance between them is less than your minimum then you will be suppressing any one of the line.
4. Feature Line:- We call a double con as a feature line when the surface after that double con has significance change(Flat surface may be attached to a curved surface or viceversa) in the geometry.

11. Next , we need to split the surfaces into smaller volumes or smaller geometeries.

12.constructing the mesh and need to be pass the mesh parameters and quality criteria.

13.As follow , finally we need to add the thickness and if neccesary we need release FE element .

Operations to obtain proper mesh flow:

Split: Split is used to split the shell and solid elements into smaller by selecting element edges and nodes.

Swap: It rotates the common edge of two shells.

Paste : It is used for manual/ automatic pasting of nodes.

Best mesh : It is the type of mesh which mesh macros using all alternative algorithm and keep only the mesh of best quality.

Reconstruction : It is used to reconstruct the mesh in FEM and macro areas.

Smooth : This option helps to smooth the mesh on selected macro areas or FEM.

Improve : This helps to improve the existing mesh.

Cut : It cuts a macro area with 2 perimeter nodes or hot points.

Join: This is used to join macro areas.

LEARNING OUTCOMES:

By performing mesh for sheet metal component, it provides the ideas and measures that should be taken into account. The learning outcomes from this meshing are as follows.

• Understand how to do the geometric checks and correct the errors happening in the check.
• Identify the thickness of the component and extract the midsurfacing by various methods.
• Providing quality criteria to the model and based on it visualise the model.
• To mesh the components to obtain a proper mesh flow using mesh elements.

This helps to get an overall undertsanding on how to perform the mesh in a sheet metal component.

CONCLUSION:

The hood model mid surface got extracted and meshed the components with proper mesh flow.

https://drive.google.com/file/d/17DLYmZEH6HR_6AjAw8QkW92rP0QcrAJn/view?usp=sharing

https://drive.google.com/file/d/1ru0VPpR0MXHWSPjIlipcwwzPVeSEdCqP/view?usp=sharing

THANK YOU !!