Week- 5 - Solid meshing

Solid Meshing

Rear View Mirror

AIM

For the given Rear view mirror component, check for the geometrical errors and mesh the Surfaces with the given 2D element Quality criterias given below.

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

S.No	Quality Criteria	Value
1	Tet collapse	0.2

STEPS TO FOLLOW :

Steps to follow in Short : Import Cad Geometry-->TOPO-->Geometry check and clean -up--> Mesh using Trias and Ortho trias-->Element Quality checks-->Vol.Mesh-->Tet Collapse checks

PROCEDURES:

In TOPO

1] Geometry checking

TOPO

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.

Geometry Checks and Fixing it

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.

[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

6] 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.

Perimeters

Macros

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

7] Measurement checkup

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

Measurments

8] 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.

Quality Criteria Including Collapse

9] Mesh parameters

Go to-tools-utilities-mesh parameters

Type of mesh- general

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

Order of element- First order

Save the setting for future reference

Mesh Parameters

10] Meshing

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

Trias and Ortho Trias

Feature region such as hemmings, fillets, in that case we should use ortho tria as element type for good mesh flow. In flat region, we can use trias From Option List.

Trias

Ortho Trias

[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. ]

11] Split in elements

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

12] Swap

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

13] Reconstruct

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

14] 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.

15] Improve

Uses both smooth and reconstruction at same time.

In Volume Mesh

16]Define

Define the volumes for the shell elements using volume mesh-volumes-define-Wholedb. Select the component one by one using PID tool.

Define

17]List

After creating property for individual component. Now we can mesh the shell elements to solid elements using v.mesh-volumes-list. Now Rightclick the defined component in list tool. After that select the remesh option. Now the mesh tool module appeared, select the method you want such as tetra rapid or tetra FEM.

Tetra Fem List

(In this project Both Tetra Fem and Tetra Rapid is done)

Tetra rapid and tetra Fem Properties

18]Mv Free

Move Free, If any 3D elements are failed for tet collapse. Use fix quality tool v.mesh-improve-fix quality. we can use another tool such as mvfree by selecting grids-mv free.

Collapse

After solving collapse

19]Not

Check the volume mesh using not tool. Hide some elements then check the volume.

Tetra Rapid

Tetra FEM

20] Release

Elements- Release to release all the drawings from geometry.

21] Save the file

Final Images

Tetra Rapid

Tetra FEM

LEARNING OUTCOMES

• The mesh should always look regular and proper.
• Surface Quality after Volume mesh should be good.
• In Vol.mesh there should not be any kinks and dips on the surface of the component.
• 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.

Conclusion:

The given Rear View Mirror assembly was meshed for the given quality criteria and assigned volumes for the 2D shell elements.