Week 3 - 2D meshing for Sheet metal

AIM: For the given hood model take out the mid-surface after checking the geometrical error and mesh the mid-surface with the given elemental quality  criteria 

GIVEN DATA: Here given data provided are 

1. QUALITY CRITERIA

S. NO	Quality criteria	valve
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
12	Tria Percentage	15

2.CAD Model 

hear provided CAD is of the Hood Panel of the car

Steps involved  

1. Fine the given  model 
2. To check all the geometry errors and rectify them
3. To check the thickness of the components in the model
4. To extract the mid surface from the geometry
5. To generate a mesh with good flow in the given quality criteria

PROCEDURE :

1 first fine given model

The given hood model component has some irregular geometrical faces to make fine the face

2 Check For Undefined Material:

PROPERTIES > Here we can observe how many components are there in the geometric

cording to how many property IDs are present. Here how many material properties are available and are they defined or not. if not we have to ONN the mark sign to define or undefined it. Then check for undefined materials in the checks manager.

3) Check The Geometry:

Here we have to check the geometry issue with CAD before going to mesh it.

It is an important stage.<< CHECKS> GEOMETRY >>On checking these PID's for geometry. We didn't get any geometrical issues. if they were not we had to do some operations to get them resolved such as releasing cones, deleting unnecessary hot points/cones, and inserting hot points if required doing Topo These operations had to be done in accordance with the problem in hand.

4) CHECK THICKNESS COMPONENT

Here we have to check the thickness of each component in order to assign it properties.

5) MIDSURFACING

There are two methods by which mid surfaces can be extracted 1. auto mid, 2 manual method For this project we only gonna use manual mid surfacing for that << FACES>OFCET >> and select the region

where the mid surface is to be extracted. The picture below shows the mids of the.

we use << FEATURE>> as there are multiple regions to select.

Feature area command gives a single click selection of our region of interest. Thus reduces region selection time.<< FACE>OFSET > FEATURE AREA AT 40 DEGREES (IT WILL ONLY SELECT THOSE WHOSE ANGLE IS LESS THAN 40 DEGREES) >>

6) Set New PID'S To MID'S

Here we set new PID's to components and refine the geometry to better understand its features.

7) Checking Mid Surface Geometry

Check the geometry again for mid-surface.was failed for multiple issues. To fix this we do the auto fix.

8) Sizing Perimeter, Defeaturing & Mesh Preparations: Change all perimeter element distances to 5mm Confirm whether perimeter element distances are in an acceptable range

By removing unnecessary HOT POINT and again resizing perimeter elements' distance we can bring distance to the acceptable range

Make sure that every hole's perimeter is even

9) Defining Quality Criteria & Meshing Parameters

Input all the given quality parameters.

10) Meshing

Definition - A mesh is a network that is formed of the cells & points .

 It can have almost any shape in any size & is used to solve partial differential equations Each cell of the mesh represents an individual solution of the equation which, when combined for the whole network results in a solution for the entire mesh.

• Select the best mesh option and click the component face to make the mesh
• If the mesh does not meet the quality criteria getting to the reconstruct option will give a better mesh flow 
• Repeat the same method for a better mesh

Note

• Trias should be less but should be kept where it is necessary
• . Trias should always move/point toward diverging sections
• . The rotational pattern should be avoided
• . Uniform perimeter element number should be ensured before meshing
• . Unnecessary hot points should be removed
• . Feature area and fillet region should be given more care.
•  Element should not fail in any quality criteria

Conclusion

• Manual mid surfaces give more accurate results
• Cut/ construction line to divide critical region for meshing helps in better mesh flow