Week 8-Challenge
Objective : 1) To cleanup the geometry to get clean mesh.
2) To generate tetra dominant 3D mesh.
3) To check the quality of elements and elimination failing elements.
CAD File :
1) Model 1
2) Model 2:
Procedure:
1) To import Cad Model:
File – Insert – Geometry – Step File – Insert
2) To clean up geometry and generating mesh.
Instead of generating Auto clean-up we will Clean-up the geometry manually. To manually cleaning the surface, we have to consider following steps:
For cleaning the geometry we have to check the distance from distance panel and then if required supress the edges, fillets and remove pin holes. We have to toggle some surface which are failing for minimum length.
To check distance between edges
Geometry – Distance – between points
To supress or toggle the surface
Geometry – Edge edit – Toggle
To remove pin holes or fillets
Geometry - Defeature Surface fillets or pin holes.
2) Changing the Quality Parameter as per given Problem Statement.
Quality Parameters are as follows.
Meshing Size : 5mm
Minimum Size : 2mm
Maximum Size : 7mm
Tet Collapse : 0.15
Preferences - Criteria File Settings – Edit
As the geometry is complex and does not have uniform thickness, we will perform 3D meshing on the surface. While performing 3D meshing, tetra elements are preferred for meshing as they can capture surface better than quad or hex elements.
3D meshing can be performed using 3 different method.
1) 2D meshing and then converting 2D to 3D using tetra mesh option.
2) Meshing using volume tetra meshing over the solid region.
3) Quick tetra meshing.
1) 2D meshing and then converting 2D to 3D using tetra mesh option.
In this method, we have to generate 2D shell elements on the surface and then using tetra mesh 2D shell, elements are converted into 3D mesh. Post that, we have to manually cleanup the geometry as well as perform meshing on surface hence, we have to delete the solids.
2) Meshing using volume tetra meshing over the solid region.
In this method we require solids as volume meshing can be performed on solid region. For this, manually cleaning of geometry is to be done.
3)Quick tetra meshing :
This the most effective way and less time consuming method as it consist of auto cleanup process. But in this type of meshing the failing elements are difficult to control.
In this model we are going to create 2D shell Elements and then convert it into 3D elements using terta mesh option
i) Generate 2D shell elements and then convert into 3D elements.
Manually performing meshing on the surface to capture whole surface properly. Selecting tria element as element shape.
2D – Auto mesh – mesh
ii) Checking for 2D element quality.
quality Index – minimum length
eliminate failing elements by remeshing the elements or by changing the density over that region.
iii) Converting 2D shell elements to 3D elements.
3D – Tetra Mesh – Elements – Mesh
Check for the tet collapse.
F10 – 3D – tet collapse
For clear visualization of element select save failed.
Mask – retrieve – mask – reverse
If there is any tet collapse then manually eliminating the elements using translate option.
Tools – translate
Check whether there is any tet collapse element or not
F10 – 3D – tet collapse
3) Component 2
While performing meshing on component 2, we got to know that the component consist of solid surface so we can easily 3D mesh using volume tetra meshing. Before using volume tetra mesh we have to change the meshing parameter
3D – tetra meshing – parameters
Change the value of minimum length to 2mm , maximum element as 7 mm and tet collapse as 0.15.
3D – tetra meshing – Volume meshing - solid - mesh
Check whether there is any tet collapse ,if there is any manually eliminate elements.
In this case we don't have any tet collapse element.
Final model:
Model 2
Objective:
- To cleanup the geometry.
- To mesh the component using tria dominant elements.
- To check quality of meshed elements.
CAD File:
Procedure:
- Import the model
File – import model – Insert.
2. To mesh the component.
As the given model is complex in structure, we are going to use 3D tetra meshing method using tetra element as, tetra elements are easy to capture over the component.
Using of quick tetra will be more sufficient in this model.
View – Browse – Hypermesh – Utility – Meshing – Quick tetra.
As per the problem statement, we have to mesh the component using mesh size as 6 mm considering minimum size of element 2 and maximum size as 8.
To check the quality of elements
If there is any tet collapse elements then manually eliminating then using translate option.
F10 – 3D – tet collapse
Final Model
Model 3
Objective : 1) To cleanup the geometry to get clean mesh.
2) To generate tetra dominant 3D mesh.
3) To check the quality of elements and elimination failing elements.
CAD File:
1) Component 1
2)Component 2
3) component 3
4) Component 4
5) component 5
6) component 6
7) Component 7
Procedure:
1) Organising the components.
As we can see, the Cad model is symmetric, hence mesh can be reflected easily from one component to another component.
To get clear model while meshing, organise the components. We will arrange the symmetric components to one components
i) To create component
right click – create – component – name – create
ii) To move desire geometry to the component
Tools - Organise – select geometry – select desire component – move
iii) Deleting the component which are not required
2) meshing the given components:
- Component 1
Instead of generating Auto clean-up we will Clean-up the geometry manually. To manually cleaning the surface we have to consider following steps:
To clean the we have to check the distance from distance panel and the if required supress the edges, fillets and remove pin holes. We have to toggle some surface which are failing for
To check distance between edges
To remove pin holes or fillets
Geometry - Defeature Surface fillets or pin holes.
If there is problem in detecting the surface then manually remove fillet surface.
Changing the Quality Parameter As per given Problem Statement.
Quality Parameters are as follows.
Meshing Size : 6 mm
Minimum Size : 2 mm
Maximum Size : 8 mm
Tet Collapse : 0.15
Preferences - Criteria File Settings – Edit
In this model we are going to create 2D shell Elements and then convert it into 3D elements using terta mesh option
Generate 2D shell elements and then convert into 3D elements
manually meshing the surface to capture whole surface properly. Selecting tria element as element shape.
2D – Auto mesh – mesh
Checking for 2D element quality
quality Index – minimum length
eliminate failing elements by remeshing the elements or by changing the density over that region.
Converting 2D shell elements to 3D elements
3D – Tetra Mesh – Elements – Mesh
Check for the tet collapse
F10 – 3D – tet collapse
If there is any tet collapse then manually eliminating the elements using translate option. In this case we don’t have any tet collapse elements.
2. Component 2
While performing meshing on component 2 we got to know that the component consist of solid surface so we can easily 3D mesh using volume tetra meshing. Before using volume tetra mesh we have to change the meshing parameter.
3D – tetra meshing – parameters
Change the value of minimum length to 2mm , maximum element as 8 mm and tet collapse as 0.15.
3D – tetra meshing – Volume meshing - solid - mesh
Check whether there is any tet collapse ,if there is any manually eliminate elements.
For clear visualization of element select save failed
Mask – retrieve – mask – reverse
If there is any tet collapse then manually eliminating the elements using translate option.
Tools – translate
3. Component 3
As the given model is complex in structure, we are going to use 3D tetra meshing method using tetra element as tetra elements are easy to capture over the component. Using of quick tetra will be more sufficient in this model.
View – Browse – Hypermesh – Utility – Meshing – Quick tetra.
To check the quality of elements
If there is any tet collapse elements then manually eliminating then using translate option.
F10 – 3D – tet collapse
4. Component 4:
In Component 4 we are going to use volume tetra meshing meshing as the model has solid surface.
Check whether there is any tet collapse ,if there is any manually eliminate elements.
For clear visualization of element select save failed
Mask – retrieve – mask – reverse
If there is any tet collapse then manually eliminating the elements using translate option.
Tools – translate
Check wether there is any tet collapse element or not
F10 – 3D – tet collapse
Reflecting the mesh
For reflecting we have to create refectence node by placing the node in between two opposite surface nodes.
F4 – between two points select - alternative point create middle point
Reflecting the mesh from one component to other using reflect option
Tools – reflect – Elements – Duplicate – reflect
Final model:
Conclusion:
1) Learned various tools used to mesh three dimensional object.
2) Got knowledge about how to eliminate 3D failing elements.
3) Different methods to mesh 3D object.
Result:
Even if we use Quick tetra meshing option, we cannot get good quality of mesh as seen in model 2. In model 2, elements are not capturing the edges properly.