Project 1 - 2D meshing on the instrumental Panel using ANSA

AIM:

To perform FE modelling of an Automotive IP trim component by considering the given element Quality criteria.

NOTE:

In this challenge, there will be some off elements found in the chamfer region which cant be removed. It is acceptable as it is been found due to the presence of triple cons on the chamfered surface. Due to those triple cons there will be some quality criteria failure which can be accpetable and those quality fails can be neglected.

GIVEN DATA:

The given data are the inputs to work. Here the given data are,

• CAD model.
• Quality criteria.

• CAD MODEL: Here the given cad model is Automotive IP trim (Plastics)

Figure 1. CAD model - Given data.

• QUALITY CRITERIA : Every product which is been produced will go through the set of quality check. If the quality check fails other steps like boundry condition & apllying loads will not be feasible, So for this reason the element quality check is performed. To identify the quality failure the quality criteria will be entered as an input data. The given quality criteria are shown in the below table. The elements should be maintained within the below given value. If the given quality value is not maintained there will be a failing in qulaity.

GIVEN DATA / INPUT

S.NO	QUALITY CRITERIA	VALUE
1.	Target/Avg length	4
2.	Min. length	2
3.	Max. length	6
4.	Aspect ratio	3
5.	Warpage	15
6.	Skewness	45
7.	jacobian	0.7
8.	Min. quad angle	45
9.	Max. quad angle	135
10.	Min. Tria angle	30
11.	Max. Tria angle	120
12.	Tria percentage	15

Table 1 : Quality criteria.

METHODOLOGY:

1. Import CAD geometry.
2. Geometry cleanup.
3. Mid surface / Skin generation.
4. Shell or solid meshing.
5. Element quality check.
6. Mesh improvement.
7. Apply load & Boundry condition.
8. Export input file.

Figure 2. Methodology.

1. Import CAD geometry:

• Input the given cad model. Here the given cad model is Automotive Instrument Panel - Trim component.
• Also enter the input values - The given quality criteria value.
• Then set Set mesh parameter - Mesh parameters is nothing but defining the meshing parameters. Once assiging the qulaity value mesh parameter has to be set.

Figure 3. Input CAD geometry.

2. Geometry cleanup:

• To generate FEM we clean up the geometry.
• Surface patch up, creating new surfaces, eleminating of triple cons in unwanted area, converting single cons to double cons in necessary area are comes under geometry cleanup phase. ANSA has some option to rebuilt the surfaces for some extent.
• By using checks manager we will check the geometry & if the error shows fix those error manually or by using autofix.

Figure 4. Geometry cleanup

3. Mid surface generation:

• This will be done once after the geometry cleanup & extraction of mid surface is an important step in CAE which has to be followed.
• Mid is the neutral pahse which is been generated from the CAD which is imported or given to us.
• The conversion of 3D cad to 2D cad is happening in mid surface generation.
• The mid surface is generated to reduce the complexity as by simplifying the cad model we get more accurate simulation results in shorter time.
• Once mid surface is extracted feed in the properties of materials & assign thickness for particular model using set PID option.

Figure 5. Mid surface of given CAD geometry.

4. Shell or solid meshing:

• Shell meshing is achieved after skin extraction but we do not mid surface all components based on requirements we should also be doing volumetric mesh.
• For casting & molding products we generally go with solid meshing.
• In this project, I have used a shell mesh for meshing the given model eventhough it is a plastic component.

Figure 6. Generation of mesh for given CAD geometry.

Figure 7. Generation of mesh for given CAD geometry.

• Assign PID - For manual mid generation PID has to assign manually. For auto mid generation (Skin/cast) PID & thickness will be assigned automatically.
  • Since it is a plastic part there will be a varrying thickness. For parts having varying thickness the average thickness can be given or multiple thickness can be given for a part by assigning seperate PID to the same parts.
  • In this challenge, I have gone by taking average thickness for the ribs having varrying thickness.
  • • • Avg thickness = (Max. thickness + Min. thickness) / 2

Figure 8. Assign PID

5. Element quality check:

• Every product which is been produced will go through the set of quality check. If quality check fails other steps like B/C & applying loads will not be feasible, So element quality check will be performed.
• The given quality criteria values been enterd in quality manager ( shortcut key : F11). These colours are customizable and can be seen while meshing if the elements are beign failed. These failed elements should be corrected and the elements should matches the quality criteria.

Figure 9. Quality checks.

6. Mesh Improvement:

• In this phase, the quality of FEM will be improved.
• After quality check any improvements that is been addressed that will be done in mesh improvement stage.

7. Apply load & BC: Loads & boundry conditions will be applied on this phase.

8. Export input file:

• Have to choose which software will read the file. As different solvers follow seperate algorithms & process.
• Decks: NASTRAN - NVH, PAM CRASH - Safety, LS DYNA - safety, ABAQUS - durability.

Draw shell as solid - Draw shell as solid should be activated after finishing challenge. Since it is a shell elements, After activating draw shell as solid the meshed shell elements will convert to solid, by considering the thickness assigned on PID. This is a final stage in this week-4 challenge which has to done before submiting.

• Step : Go to Quality criteria (short cut key - F11) -->presentation parameters --> Select Draw shell as solid ---> OK

Figure 10. Shows the differences before & after selecting draw shell as solid

Figure 11. Details of elements

LEARNING OUTCOMES :

At the end of this challenge, I can able to

• Easily perform FE Model building for any complex automotive components with a good mesh flow.
• Work on ANSA with a flow.

CONCLUSION :

Hence, the geometrical errors and 2D mesh, with the given element Quality criteria has been performed successfuly for a given Automotive IP Trim component. As per methodology, From import cad, geometry clean up to mesh improvement phases have been performed successfuly. The Applying load & Boundry condition phases will be performed on upcoming challenges.