Week 12:Project 2-Meshing of Rear Wheel Holder challenge
Week 12:Project 2-Meshing of Rear Wheel Holder challenge
Objective
To create a 2D mesh of the expected quality criteria for the Rear wheel holder model using Hypermesh.
CAD Model Image
Procedure:
The completion of the model was done in the following process:
- Extracting mid-surface from all the components
- Cleaning up the geometry
- Creation of 2D shell mesh
- Checking for continuity and quality.
i. Extracting mid-surface from all the components
The given Rear wheel holder model is a sheet metal model and therefore has uniform thickness.
The mid-surface was extracted using Geom`rarr`surface edit`rarr`offset option.
One face of the component was offset to half the thickness of the component.
The component is a sheet metal part and has a uniform thickness of 0.75 units. The offset of the top surface was done for 0.375 units
The mid-surface was assigned to a new component card.
ii. Cleaning up the geometry
The surface was cleaned up to ensure that the elements meet the quality criteria and have a good flow.
In areas having two shared edges close together, the elements would fail in the minimum length criteria and hence one of the lines were toggled off or a new mid-line was created and the other two were toggled.
Some lines were toggled entirely since they would affect the flow of mesh. New lines were made on the surface to maximize good flow of elements.
Small holes on the surface were filled using the filler surf option. These features were neglected since their diameter is very small when compared to the minimum element length of the quality criteria.
iii. Creation of 2D shell mesh
Mesh generation:
After the components' geometry have been cleaned up, the mesh was created on the surface.
To create a 2D shell mesh, the 2D`rarr`automesh`rarr`surfs option was used.
The mesh density was controlled on the edges to create a balance between good mesh density and tria concentration.
Some tweaks were also made on the mesh style wherever necessary to obtain a good automatic mesh generation.
The biasing was adjusted to remove opposing trias, to straighten the mesh when it wasn't straight.
Mesh flow:
After the mesh was automatically generated, the elems option was used to select smaller groups of elements in order for the mesh algorithm to work better and create a better mesh removing rotating quads and pattern trias.
Apart from this, the cleanup tools such as swap edge, drag tria element, combine tria elements were used to remove opposing trias and to drag them out the edge.
The smooth option was used to smoothen the elements to create a mesh that is even in spacing and without any abrupt and jagged edges.
Since this component contained a lot of irregularities, features and uneven surfaces; care was taken to ensure that the elements were captured all the features and stayed within the geometry lines.
iv. Checking for continuity and quality
Mesh Connectivity:
The Tool`rarr`edges`rarr`find edges option was used to check for unconnected elements. This is crucial in mesh generation as an unconnected mesh causes errors while processing.
The elements that weren't connected were connected using the 2D`rarr`replace option to connect nodes.
Duplicate elements were deleted and new elements were created wherever necessary using the edit element`rarr`create.
Checking for quality:
The given element criteria was entered into the Criteria file settings window.
When the color mode view is changed to show element quality, the elements which fail the criteria were highlighted, and they can be corrected using elem cleanup option, However this option tends to make the nodes stray out of the geometry lines and so the failed elements were re-meshed.
The 2D`rarr`quality index`rarr`QI settings option was used for more specific corrections. The failed elements were saved and retrieved in the mask option. The isolated elements were then corrected.
This was continued until zero failed elements remained.
Final Model Image
