Meshing of Rear Wheel Holder in Hypermesh

Objective: To generate 2D mesh on the rear wheel holder geometry.

Procedure:

1. Import the given geometry file into hypermesh.

Fig 1: Imported geometry file.

2. The button surfaces are deleted from the geometry, and a new plain surface is created in their place because elements will be failed to satisfy the criteria required.

3. Surface clean-up is the crucial thing to do. Free edges are cleared in the geometry by using quick edit and surface edit options. Proper surface clean-up is required to generate an excellent mid surface.

Fig 2: Geometry after surface clean-up.

4. The mid surface for the component is generated by midsurface option in the geometry tab. Keeping the extraction option as offset+planes to successfully render the mid surface of the geometry.

Fig 3: Generated mid surface of the component.

5. The mid surface generated would also be having some surface glitches and errors; these should also be cleared by using quick edit and surface edit options. Once these are done, check for the free edges again and make sure there're no free edges inside the geometry.

Fig 4: Surface clean is done, and no free edges are present inside the geometry.

6. For achieving proper mesh flow, necessary splits are done on the mid surface in a rectangular manner. With the help of quick edit options, unwanted surface lines are toggled, and new ones are created with node to node or with node to line commands. Auto mesh is generated in each of the rectangular boxes, with five units as element size and mixed element type. Since the rectangular sections are made, all quad elements will be generated if any tria is formed in a particular area. They can be removed either by remeshing or with cleanup tools in the quality index. Other than these options dragging trias out of the mesh, combining two opposite trias, splitting, combining, and creating elements, generate maximum quads and least tria elements.

7. Smoothing and element optimization is done to ensure proper flow and orientation of the mesh. Finally, element check is done by assigning the criteria as:

Target Element Length = 5 Units

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2 Units
6	Max. Length	8 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

With these above criteria, the generated mesh is checked for each condition; if criteria fail to fall under the requirements, manual mesh methods can correct the mesh.

Fig 5: Created elements satisfy all the given quality criteria.

Fig 6: Generated mesh on the component.

*** While doing splits in the surface, the features should not be altered drastically, and few feature edges cannot be suppressed because it disturbs the mesh, and element failure happens at those regions. Some of the feature edges should be preserved, and additional lines must be created accordingly.

When tria elements are formed, surrounding elements are selected along with the tia element and meshed again. It may be possible to remove the tria and create a quad element. Again this is a trial and error method to remove tria elements from the mesh. We aim to reduce trias as much as possible because tria elements are stiffer than quad elements; the presence of trias may result in inaccurate results.

8. Upon successfully meshing one side with resolving all the elemental issues, the elements are duplicated and reflected on the other side to get the complete meshing of the surface. After reflecting, check for the connectivity of nodes if any are disconnected; they can be connected with equivalence and replace options.

9. Create a new material named steel and assign the value of 'E', 'NU', and 'RHO". A new property is created to give thickness for the mid-surface with PSHELL as card image, and thickness of 0.75 unit is entered.

Fig 7: List of model items.

Conclusion: 2D mesh was generated on the rear wheel holder component with an element length of 5 units, satisfying all the mentioned element criteria.

Fig 8: Detailed view of 2D mesh on the rear wheel holder.