Assignment 1
Assignment 1 (Solution)
Carry out the following geometry cleanup operation on the given components
- Clean the geometry
- Extract mid surface
- Clean mid surface geometry
- Ignore holes less than dia 5mm
- Create a 2D mesh with target length 5mm, min 3.5mm max 7mm
- And assign proper thickness, by creating a generic property
1. Solution for Part-1:
Figure-1 describes the component under consideration for mesh study.
Geometry Cleanup
The component was checked for any free lines and connection issues. Figure-2a and Figure-2b show the wireframe view of the component showing two regions having free lines and seven regions with connection issues, respectively. The free edges errors were rectified by finding and deleting in the check element feature. Also, the connection issues were rectified using toggle edge using appropriate tolerance. The wireframe view of geometry after the geometry cleanup is illustrated in Figure-3. The component is ready for mid-surface extraction.
| (a) | (b) |
Mid-surface Extraction
For generating 2D shell mesh, the mid surface of the component was extracted using the mid-surface feature in geometry. The closed body used for extraction and the extracted mid-surface is illustrated in Figure-4a and Figure-4b, respectively.
| (a) | (b) |
Mid-surface Defeaturing
To obtain a good mesh flow, holes less than 5mm were filled and surface & edge fillets were de-featured. They are described in Figure-5a, Figure-5b and Figure-5c, respectively. Figure-5d describes the final defeatured geometry for 2D shell mesh generation.
| (a) | (b) |
| (c) | (d) |
2D Shell Mesh Generation
The mesh was checked for free edges and duplicate nodes. No such entities were found. The mesh was generated using the auto-mesh feature and was refined according to the element criteria defined in Table-1. Figure-6a and Figure-6b show the meshed component before and after performing mesh refinement. Here, it must be noted that the min element size of 3.5mm could not be maintained near the hole (greater than 5mm )(refer Figure-4a) in and the chamfers (defeatured fillets).
| Parameter | Value |
| Target Element Size | 5 mm |
| Min Edge Element Edge Length | 3.5 mm |
| Max Edge Element Edge Length | 7 mm |
| Aspect Ratio | 5 |
| Warp Angle | 10 degrees |
| Jacobian | 0.6 |
| Skewness | 60 degrees |
| Tri-Min Angle | 20 degrees |
| Tri-Max Angle | 120 degrees |
| Quad-Min Angle | 40 degrees |
| Quad-Max Angle | 140 degrees |
| (a) | (b) |
Post-Mesh Operations
The elements were re-numbered. Approximately, 480 elements were generated. Also, the elements normals were checked and have been illustrated in Figure-7a. Also, the 2D mesh was mapped to the 3D geometry using organise feature and a thickness of 2mm was applied. Figure-7b illustrates the final mesh in 3D representation (with thickness).
| (a) | (b) |
Solution for Part-2
Figure-8 describes the component under consideration.
Geometry Cleanup
No free lines or connection issues were found. The wireframe view of the component is described in Figure-9a. The component is ready for mid-surface extraction as evident from the closed body representation in Figure 9b.
Mid-surface Extraction
For generating 2D shell mesh, the mid surface of the component was extracted using the mid-surface feature in geometry. The extracted mid-surface is illustrated in Figure-10.
Mid-surface Defeaturing
To obtain a good mesh flow, holes less than 5mm were filled using filler surf feature and surface fillets were de-featured using surf fillet feature. Here, ten holes were found having a diameter less than 5mm and have been filled using pinholes feature in geometry defeaturing options and is illustrated in Figure-11a. Again, the surface fillets were defeatured using surf fillets feature in geometry defeaturing options and have been illustrated in Figure-11b. Furthermore, the edge fillets, illustrated in Figure 11-c, were removed using the edge fillet feature in geometry de-featuring options. The final de-featured geometry along with the appropriate washer split (5mm) and surface partitions is illustrated in Figure 11-d.
| (a) | (b) |
| (c) | (d) |
2D Shell Mesh Generation
The mesh was generated according to the parameters defined in Table-1. Figure-12 illustrates the final mesh geometry after mesh refinements.
Post-Mesh Operations
Again, the elements were re-numbered. 992 elements were generated. Also, the elements normals were checked and have been illustrated in Figure-12a. Also, the 2D mesh was mapped to the 3D geometry using organise feature and a thickness of 2mm was applied. Figure-12b illustrates the final mesh in 3D representation (with thickness).
| (a) | (b) |
Solution for Part-3
Figure-8 illustrates the component under consideration.
Geometry Cleanup
No free lines or connection issues were found as observed from the wireframe view of the component illustrated in Figure-14a. The component is ready for mid-surface extraction as evident from the closed body representation in Figure 14b.
Mid-surface Extraction
For generating 2D shell mesh, the mid surface of the component was extracted using the mid-surface feature in geometry and has been illustrated in Figure-15.
Mid-surface Defeaturing
To obtain a good mesh flow, holes less than 5mm were filled using pinhole feature in the geometry defeature options. The holes that were defeatured are illustrated in Figure-16a. Also. Figure-16b describes the lines that were toggled using toggle edge feature in geometry edit options to avoid the generation of small elements.
| (a) | (b) |
2D Shell Mesh Generation
The mesh was generated according to the parameters defined in Table-1. For ease of handling, the mesh was performed on a quarter model of the component as illustrated in Figure-17a. The mesh was then mirrored about the two planes of symmetry to obtain a complete mesh. Figure-17b illustrates the final meshed component after mesh refinements.
| (a) | (b) |
Post-Mesh Operations
Again, the elements were re-numbered. 298 elements were generated. Also, the elements normals were checked and have been illustrated in Figure-18a. Also, the 2D mesh was mapped to the 3D geometry using organise feature and a thickness of 2mm was applied. Figure-18b illustrates the final mesh in 3D representation (with thickness).
| (a) | (b) |
Conclusion
In this assignment, three components have been considered for a geometry clean up followed by 2D shell mesh generation for a mesh size of 5mm (Min = 3.5 mm and Max = 7 mm) over the extracted and cleaned mid-surface. Holes less than 5mm were ignored and the constant thickness of 2mm was applied to the elements.
The final models (.hm files) for the three models have been included with this submission for review.