Week 3

Objective:

To extract the mid surface and generate 2D mesh for the given hood component of a car according to the given element quality criteria using ANSA.

S.No	Quality Criteria	Value
1	Target/Average length	5
2	Minimum Length	3
3	Maximum Length	7
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum  Tria Angle	30
11	Maximum Tria Angle	120
10	Tria Percentage	15

Methodology:

• Geometry cleanup
• Midsurface extraction
• Assigning shell property
• Meshing as per criteria

Procedure:

As the given component is a sheet metal part, its thickness is very less. So instead of going for 3D meshing, we can go for 2D meshing.

The hood has four separate parts, which are Hinge reinforcement, Latch reinforcement, an Inner panel and an Outer panel.

The Four parts are shown as follows:

1)Hinge Reinforcement:

2)Latch reinforcement:

3)Outer panel:

4)Inner panel:

1.Geometry cleanup:

The given component is subjected to geometry cleanup.

The errors are checked and fixed using various module buttons in Topo module. After fixing the errors again geometry checkup is done to ensure that all the errors got fixed.

2.Midsurface extraction:

The mid surfaces of the four parts are extracted separately.

The outer and inner panel is checked for symmetry using Rm.Dbl module button under faces option. Due to the symmetrical property, one half of the part is selected to extract the mid surface and Meshing. 

Under Faces module Button in Topo module, offset option is selected and feature mode is selected because the part is of the same thickness value all around and then face is selected and the Mean value is entered in the offset window and then the mid surface was extracted.

The mid surface image for all the parts as shown as follows:

3.Assigning shell property:

In the property tab, the mid surfaces are selected and renamed accordingly to their names.

The thickness values of each part are entered and their type is chosen as PSHELL.

The thickness property is applied successfully.

Hinge reinforcement(thickness 1.2 mm)

Latch reinforcement(thickness 1.2 mm)

Inner panel(thickness 0.75 mm)

Outer panel(thickness 0.75 mm)

4.Meshing:

• The given element quality condition is entered into the quality criteria tab and it is saved.
• The quality criteria & mesh parameters values are entered.
• The perimeter length and Macro value assigned as 5 mm.
• Using the best mesh option each macro area is selected and meshed.
• In order to get a proper mesh flow construction lines are rearranged.
• The quality criteria are achieved by using tools like cut, join, Num +/-, reconstruct, smooth and split options.
• The tria percentage is reduced by deleting unwanted construction lines without losing the feature.
• Then symmetry for the outer and inner panel is taken by using the copy option in Transform module button under the utilities option.
• The meshed model of the hood is as shown in the figure.

Conclusion:

The given hood model of a car is imported to the ANSA software and the geometrical errors are fixed. The mid surface for each component of the hood is extracted and thickness is assigned. The mid surface part is meshed successfully by satisfying the quality criteria.  

Learning Outcomes:

• Learnt the usage of various tools of ANSA software.
• Able to fix the geometrical errors for the given model.
• Able to extract the mid surface and assign the thickness value under new property id.
• Able to mesh the given model by satisfying the quality criteria.