Meshing of Side Door Geometry of a Car

OBJECTIVE:

1. To mesh the given model of side door geometry of a car.
2. Generate mid surface and perform geometry clean-up of the component
3. Generate mesh with low tria concentration and proper mesh flow
4. Satisfy all the below given quality parameters
5. Assign thickness to the component

Target Element size - 4mm

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.2
5	Min. Length	2mm
6	Max. Length	6mm
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

SOLUTION:

The objective of the project is to perform meshing of the given component. The component provided for the task is a passenger vehicle side door. For performing proper meshing of the component, the component may be split into 4 parts and each of these parts needs to be separated and meshed individually. The mid surface of each parts has to be extracted and geometry clean-up needs to be performed. The meshing should be done using mixed elements and maintaining minimum tria element concentration. The final mesh has to satisfy all the given quality parameters and should have a god mesh flow.

Step 1:

The side door component was split into 4 parts as shown below. This can be done using surface edit option in the geometry panel.

Step 2:

The mid surface for each part was extracted manually using surface offset option. Care was taken to include all the features and ribs in each of the parts. Before mid-surface extraction, some geometry cleanup was performed on the given model.

Step 3:

After extracting the mid surface, the geometry clean-up of the surface was carried out. It was observed that some surfaces were missing due to the mid surface extraction. Some surfaces were manually created to fill the gaps. The given parts have multiple features of varying shapes in the geometry. When the meshing is performed, it is highly probable that the surfaces adjacent to these features is not captured properly. To better capture the geometry, washer splits may be created around these features, so that the area covered inside these lines is given a dedicated mesh flow. Further, depending on the feature geometry and size of the component multiple split line may be provided around the features. This was done using the quick edit option in the Geom panel.

Step 4:

The mesh was created using mixed element of 4mm size using the automesh option in 2D panel. This is a computer generated mesh and requires clean-ups to satisfy the quality parameters and for good mesh flow.

Step 5:

Since the mid surface was manually created, some of the ribs and the base plate were not connected properly. This was reflected in the mesh generated, as the mesh didn’t have proper connections and the mesh was not free flowing. This issue was resolved by using the replace node option in the 2D panel and connections were given between appropriate nodes. Further the alignment of the nodes were also corrected to get a free flowing mesh.

Step 6: Mesh clean up

The mesh generated is supposed to have a good flow and satisfy all quality criterions. Some steps to achieve the same is as described:

1. Some modification in the mesh can be brought by controlling the changing the number of elements at the different sections. This action can be performed at the initial step of meshing.
2. For removing local element concentration and to imparting good mesh flow, the elements in these areas may be selected and meshed again. Sometimes, multiple iterations may be required to get a good mesh.
3. For generating the mesh of required quality, various tools are available in the quality index and elem cleanup options in 2D panel.
4. Some commonly used tools for generating good quality mesh includes element optimize, place nodes, combine tria elements, split quad elements, cleanup, automesh, check elements and so on.

Step 6: Material and Property

The material for components were selected as Steel and the material parameters were defined. The component has different thickness for different features. Hence for assigning thickness, the parts were divided into groups and appropriate thickness was assigned to each group. This can be done by creating a thickness property and assigning it to the component.

The final meshed component is as shown below:

Conclusion:

1. The different parts from the given component were separated and meshed.
2. The mid surface for each part was extracted and geometry cleanup was performed on the part.
3. All parts were meshed using quad elements and the mesh was modified to get good mesh flow.
4. Further each quality parameter, as defined in the problem statement, was cross checked and necessary changes were incorporated into the mesh.
5. Connections were given between appropriate nodes so as to get a free flowing mesh all along the component.
6. Parts were divided into groups and appropriate thickness was assigned to each group accordingly.