Week 12:Project 2-Meshing of Rear Wheel Holder challenge

AIM - To Mesh The Rear Wheel Holder Of The Car.

OBJECTIVE:

• To extract a good midsurface for meshing.
• To repair the midsurface for missing surfaces.
• To mesh the Rear Wheel Holder with proper Mesh Flow and low Tria Percentage.
• To satisfy the quality criteria.

CAD MODEL IMAGES:

PROCEDURE:

• At first the file was imported.
• Then after importing the midsurface was extracted using the command geom → midsurface → Auto midsurface (Extraction Method - offset). Extraction method was chossen offset because the Rear Wheel Holder is a sheet metal component. After completion of the auto midsurface process a fine midsurface was achieved. No geometry cleanup was done on the parent geometry because without geometry cleanup I got a good midsurface with few surface issues.
• Then few surfaces were missing on the midsurface so they were created using command geom → surfaces → Ruled.

• The below mention feature was removed and surface was filled using command geom → quick edit → filler surface to achieve better mesh flow.

• After successfully extrating and repairing midsurface Meshing process was started.
• For meshing the Quality criteria setting was done under preferences → criteria file settings. Below is table for given criteria standard.

S.N	QUALITY CRITERIA	VALUE
1	Traget Element Length	5 Units
2	Minimum Length	2 Units
3	Maximum Length	8 Units
4	Aspect Ratio	5
5	Skewness	45
6	Warping	15
7	Taper	0.5
8	Minimum Angle Quad	45
9	Maximum Angle Quad	135
10	Minimum Angle Tria	20
11	Maximum Angle Tria	120
12	Tria %	10

• After setting the Quality criteria Meshing was started. I started the meshing right from the centre of the component and moved towards the outer surface of the wheel holder. I meshed the whole component instead of choosing for symmetry because in genaral symmetrical surface makes task easier but over here it was more laborious for me cause around roughly 60% surface was symmetrical and working on symmetrical approach would have created problems like 1) Repalcing lots of nodes on the junction where the surface are not symmetrical and remeshing, 2) Controlling the mesh flow from outer wheel holder surface to inner, because the outer surface is larger and inner surface is smaller comparitively so this would have created the problem in adjusting the number of nodes which will trigger problem number 1 as discussed above. and it will create more confusion. On the other side I found that there are many retangular surface which can be meshed easily and fast so I went with manual shell meshing the whole component.

• For few features that were on the outer surface of the component mesh was reflected cause they were symmetrical on the other side also. Below are the images shown.

• There were few feature which was not suppressed cause I wanted to capture geometry as it is and it cause elements to fail in those region.

• After successfully meshing the surface work was done on trias that were touching each other or were opposite they were removed.
• Then certain checks were performed like 1) Free edge check tools → edges (select the elements and use the default tolerence), 2) Normals, 3) Dependency and 4 ) penetration.
• After that thickness was assigned to the component by creating property and material MAT1 was also created. Then the parent geometry surfaced was turned on and the mesh was turned to check whether the shell elements are capturing the surface properly or not.

• The above image shows thickness assigned elements in 2D detailed representation and it shows that the surface or component is properly captured by element thickness.

RESULTS:

1. A good midsurface was achieved for the given Rear Wheel Holder.
2. A good Mesh flow was achieved with around 3.0% Trias.
3. The quality criteria was satisfied except for features that was not suppressed where the elements failed.
4. A proper Thickness was assigned the 2D shell elements to capture or replicate the original sheet metal Rear wheel holder thickness.