Week 6-Meshing of Hood Challenge

Skill-lync assignment (week 6)

Aim: The objective of this assignment is to create representative mid-surfaces for the given components and to create 2D shell meshes for them as per the given criteria.

Case setup: The component is a complete model of a car bonnet, as illustrated below.

Figure 1: Complete hood model

It is comprised of a total of 5 separate parts that include an upper & lower panel, 2 hinge plates and a latch plate. It is to be meshed as per the following quality criteria: -

Table 1: Quality criteria for 2D shell mesh

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

Procedure: The components are worked on through the following sequence of steps: -

1. The component geometry is imported into the Hyper-works workspace.
2. The preferences>criteria file settings menu selection is then used to input the necessary quality criteria.
3. The latch section is isolated and its mid-surface is extracted, as shown below.

Figure 2: Mid-surface of latch section

4. The mid-surface is checked for geometric errors and unnecessary edges & fillets are removed by the Geom>defeature tab. The hole in the middle of the component is given a washer split 5 units wide.
5. The latch mid-surface is set as current, so that the mesh generated for it is associated to it. The 2D>automesh tab is used to create the mesh for the component, starting from the washer section. The mesh is rebuilt and edited by a combination of aligning nodes and smooth operation to generate the washer mesh, as shown below.

Figure 3: Mesh generated for washer region

6. The remaining mid-surface is meshed section-by-section. Each time the mesh is checked for element quality through the use of the 2D>qualityindex tab. Whenever the overall mesh is inadequate, it is rebuilt using the 2D>rebuild mesh tab. If the rebuild mesh tab is not enough, the mesh is manually edited using the clean-up tools in the qualityindex tab.
7. A final check is performed for the element normal vectors and the free edges by the Tool>normals and the Tool>edges tabs.
8. After the mesh is completed for the mid-surfaces, the other parts & components are deleted and the file is saved.
9. In a new Hyper-works session, the original file is imported and the left hinge section is selected for mid-surface and meshing.
10. Steps 3-8 are repeated for the left hinge section.
11. Steps 3-8 are repeated again for the remaining sections.
12. For the inner & outer panel sections, half of the section is meshed on one of their symmetric sides. The resultant elements are then duplicated and reflected onto the side using the Tool>reflect tab. The elements at the boundary of the symmetry plane are connected together using the equivalence option in the Tool>edges tab.

Result: The final meshes for the various sections are listed below.

Figure 4: Final FE mesh of latch reinforcement section

Figure 5: Final FE mesh of left hinge reinforcement section

Figure 6: Final FE mesh of right hinge reinforcement section

Figure 7: Final FE mesh of outer panel

Figure 8: Final FE mesh of inner panel