Challenge

Week 3-Meshing of Hood Challenge

AIM: The main aim of this challenge is to mesh the given car hood inner panel as per below element quality criteria.

S.no

Element Quality Criteria

Value

1

Target/Average length

5

2

Minimum Length

2

3

Maximum Length

8

4

Aspect

5

5

Warpage

15

6

Skewness

45

7

Taper

0.5

8

Minimum Quad Angle

45

9

Maximum Quad Angle

135

10

Minimum Tria Angle

20

11

Maximum Tria Angle

120

12

Tria Percentage

10

OBJECTIVE: The objectives of this challenge are as follows:

<!-- [if !supportLists]-->1.     <!--[endif]-->To perform geometry clean up and generating mid surface for the given component.

<!-- [if !supportLists]-->2.     <!--[endif]-->To mesh the given component with less tria concentration and good mesh flow.

<!-- [if !supportLists]-->3.     <!--[endif]-->Finally all the elements should pass for given element quality criteria.

PROCEDURE:

<!-- [if !supportLists]-->1.     <!--[endif]--><!-- [if gte vml 1]> <![endif]--><!-- [if !vml]--> The CAD file in Hypermesh can be opened by selecting import model option.

 

<!-- [if !supportLists]-->2.     <!--[endif]-->After opening the file, manual cleanup was performed in order to remove free edges and non-manifold edges.

<!-- [if gte vml 1]> <![endif]--><!-- [if !vml]-->

<!--[endif]--><!-- [if gte vml 1]><![endif]-->

<!-- [if !supportLists]-->3.     <!--[endif]--><!-- [if gte vml 1]> <![endif]--><!-- [if !vml]--> Several commands like split surface, toggle edges& delete surfaces were used from quick edit sub panel (GEOMETRYàQUICK EDIT).

 

A    After removing all the free edges and non-manifold edges by manual cleaning, mid- surface was extracted using skin offset method (GEOMETRY à MIDSURFACEà EXTRACT OPTIONSàSKIN OFFSETàAUTO EXTRACT).

 

       Since the given component is symmetrical (except at the latch portion), half of the component was deleted as shown in below image followed by manual cleanup.

 

<!-- [if !supportLists]-->6c After deleting half of the surfaces, washer splits of 5mm were created for all the holes and slots using quick edit sub panel (GEOMETRYàQUICK EDIT).

 

<!-- [if !supportLists]-->7.    After creating washer splits, meshing was performed using auto mesh command by importing the quality criteria (2DàAUTOMESH).

<!-- [if !supportLists]-->8.     <!--[endif]-->Elements failing at the critical features were then corrected using commands like split quad element, swap edges, element optimize, node optimize, smooth etc from quality index sub panel (2DàQUALITY INDEX).    

       The final component after meshing is shown in the below image.

 

<!-- [if !supportLists]-->10The other half of the surface and elements were then reflected using reflect command (TOOLSà REFLECT).

 

CHECKING: After finishing the following checks must be performed:

<!-- [if !supportLists]-->1.     <!--[endif]-->Checking for free edges in the component to ensure nodal connectivity. If any free edges are present in the middle of the component, those free edges can be removed by equivalence option or pasting the nodes manually (TOOLSà EDGES).

<!-- [if !supportLists]-->2.     <!--[endif]-->Checking normals (TOOLSà NORMALS) of the elements to ensure a consistent normal is maintained for the given component.

<!-- [if !supportLists]-->3  To find whether a proper contact has been established between elements and surfaces, we must do surface comparison (GEOMETRYàCHECKàSURFACEà COMPARISION).

<!-- [if !supportLists]-->4.     <!--[endif]--> Check for penetrations and dependency.

<!-- [if !supportLists]-->5.     <!--[endif]-->After all the checks, finally a property has been created with 0.75mm thickness and assigned to the component. To visualize this, we have to change the 2D traditional elemental representation to 2D detailed elemental representation.

CONCLUSIONS:

<!-- [if !supportLists]-->1.     <!--[endif]-->Learnt about geometry clean up and extracting the mid surface using skin offset method.

<!-- [if !supportLists]-->2.     <!--[endif]-->Learnt about how to mesh a component for a given quality element criteria.

RESULTS:

 

Geometry cleanup, mid surface extraction and meshing of the given component was done successfully. Trias concentration was limited to less than 2%.

Note: cant able to attach the file. link for the file: https://drive.google.com/file/d/1Uv2ngzN-G3YRsqZadJiT-rlCNAy9ev2N/view?usp=sharing

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