Week - 4 - 2D meshing for Plastic components

Project: 2D meshing for Plastic components

Model Taken: Bottle Cap

Aim:

For the given Plastic Bottle Cap model, check for the geometrical errors and take the mid surface by suitable mid surfacing techniques. PID and Thickness assignment has to be done for all the mid surfaces. Mesh the same with given element Quality criteria.

Si.No	Quality Criteria	Value
1	Target/Average length	1
2	Minimum Length	0.5
3	Maximum Length	3
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

STEPS TO FOLLOW :

Steps to follow in Short : Import Cad Geometry-->TOPO-->Geometry clean -up-->Midsurface generation-->Shell meshing-->Element Quality checks

PROCEDURES:

In TOPO

1] Geometry checking

After downloading the drawing Geometry, release cons and apply TOPO. Then go for a geometry check. Normally if cons are generated select all then clear it by Right click and fix. If not clearing tough fix manually. In this case after selecting all, go for right click and fix. All errors are cleaned and geometry is perfect. If not go for individual checks and cleaning.

Single Cons(represented by red colour lines) - Edges which are shared with only one surface should be single cons. Single cons denote there is no connectivity between the surfaces in the model.

Double Cons(represented by yellow colour lines) -If any edge shared with two surfaces the that line is called Double Cons.

Triple Cons(represented by cyan colour lines) – if any edge is shared with three or more than three surfaces then that line is called triple cons.

Topology describes how elements are bounded and connected and Geometry describes the shape of each element.

2] Locking

The next part is locking the parent parts in order to take parent part alone.

3] Save

Save the settings, from tools- settings and save the file

4] Orient

Apply orient on every mid surfaces, grey on top and yellow on bottom.

Go to module buttons-Faces-Orient-Select

5] Measurements

Apply measurements on every surface and store.

6] Offset / Middle method

Go to- Topo-Faces-Offset- then on the feature area- and make offset alone those parts which have uniform thickness.

Then separate it from parent part by i-not function.

Try not to delete parent part.

Due to this is a plastic component I have applied both the middle option and offset method.

[Cleanup the mid surface for the meshing. Edit the cons and faces using cut, project cut, release, paste, orient and topo options to clean up the geometry for meshing]

In Mesh- Classic Mesh

7] Applying Perimeters

Go to- classic mesh- perimeters- select all-apply perimeters as 1.

Perimeters are the dots b/w two points on mesh on boundaries.

Go to- classic mesh- perimeters- select all-macros as 1.

Macros are the dots b/w two points on mesh on boundaries.

(Defeaturing- Is used to remove unnecessary surfaces radius, pin holes, edges. In short To neglect one criteria and doing adjustments in another.)

8] Measurement checkup

Check the measurements whether the surfaces are coming under our quality criteria, if not arrange the by using cut in macros.

9] Counting the numbers

Go to perimeter- number to count the numbers and make it into even.

10] Mark and unmarking hotpoint

Points around feature areas are Marked after checking numbers else if after reconstruction shape or numbers may vary.

11] Quality Criteria

Apply the quality criteria given, by pressing 'F11'.

Go to- presentation prameters- put tick in elements

Enable range- apply - okay

Then save the settings.

12] Mesh parameters

Go to-tools-utilities-mesh parameters

Type of mesh- general

Element Type- Mixed( It’s a mix of quad and tria elements)

Order of element- First order

Save the setting for future reference

13] Part ID

Create new properties and apply thickness

For using mesh we use 3 tabs mainly-1]Mesh Generation

-2]Shell Mesh

-3] Elements

14] Extend

To extend the surface.

15]Intersect

To intersect two surfaces.

16]Curves

There is an enormous number of function for curves, used to make new surfaces, used to take mid planes, to get an rough boundary for lines, etc.

Here curves has an important role in making thread lines inside the sufaces.

17] Meshing

Apply Best mesh/ Free mesh to mesh the surfaces. Mesh the surface components independently.

[In the hemming region(in the Outer panel’s bend region), Elements will fail for the Min length error due to the very small surface to capture the curved surface. In order to solve this Min length error, go for ‘defeaturing’ the mid surface. ]

18] Symmetry

In this case ribs inside are in equal distance so we can apply symmetry for that we need to go for Points- On COG create centre points. Go to Transform- copy- Rotate by giving angle

19] Deleting hot points

By hot points- delete, for deleting unwanted nodes.

20] Split in elements

Used to delete unwanted trias and to generate a straight line by splitting the lines.

21] Swap

Used to delete unwanted trias and to redirect the line to another node.

22] Reconstruct

If the mesh flow is not perfect go for reconstructing the mesh and rerunning them will make perfect.

23] Smooth

If the mesh flow is not perfect and after split usage and lines are not keeping uniform distance go for smooth function in the mesh to make perfect line mesh.

24] Improve

Uses both smooth and reconstruction at same time.

25] Property ID

Create property id to assign thickness to the elements.

26] Join

Macros - Join to keep lines in mesh what we have drawn

27] Draw shell as solid

To find the mesh into solids by assigning thickness. Founds in Quality criteria - Presentation parameters

28] Release

Elements- Release to release all the drawings from geometry.

29] Save the file

LEARNING OUTCOMES

• The mesh should always look regular and proper.
• No two opposite trias came back to back, if came go for smooth option.
• By swap, tria's side can be moved or removed if unnecessary.
• The edges in ANSA are called cons and single cons are highlighted in red color, double in yellow color and triple in blue color. Double edge is shared by two surfaces and triple by three. Single cons are open edges.
• Aspect ratio is the ratio of maximum length to the minimum length
• Jacobian is a measure of deviation of a given element from an ideally shaped elements.
• Skewness is the Angular Measure of Element quality with respect to the Angles of Ideal Element Types.
• Maximum Angle out of the two possibilities is reported as "Warp Angle".

CONCLUSION

The given bottle cap model is meshed with given quality criteria using mid surface and assign various thickness among the surfaces.

The quality criteria was satisfied for the given quality parameters.