WORKSHOP 8 SPRINGBACK ANALYSIS OF A JET ENGINE COWLING презентация

2004
Copyright© 2004 MSC.Software Corporation

shape of a layup, once cured and cooled to ambient temperature, can be different than the mould shape. If the shape is too different a “springback” correction and analysis is required. This is the other focus of this workshop.
Other things are required in this workshop, such as
Create plies
Create a layup
Visually determine if the plies and layup were correctly created
Run MSC.Nastran to determine the deformed shape of the model due to cooling to ambient temperature

a session file
Create material properties by reading a session file
Create a new layup file
Create an MSC.Laminate Modeler material
Create plies using MSC.Laminate Modeler
Create MSC.Laminate Modeler layup
Check plies using MSC.Laminate Modeler
Check layup using MSC.Laminate Modeler
Apply uniform temperature in MSC.Patran
Create nodal displacement constraints in MSC.Patran
Run the analysis using MSC.Nastran
View the deformation results
Compensate the FE Model for the springback
Export the compensated FE model
Create a new MSC.Patran database
Import the compensated FE model from IGES file
Optional task

OK.
Click OK.

Step 1. Create a New Database

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a session file.
File / Session.
Click Play.
Select springback_geom.ses as the File name.
Click -Apply-. (This action will cause the session file to be read. Please do not interrupt it.)

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by Reading a Session File (Cont.)

will cause the session file to be read. Please do not interrupt it.)

Step 3. Create Material Properties by Reading a Session File

the file name.
Lick OK.

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Step 4. Create a New Layup File

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Material.
Enter 0.25 for the Thickness.
Click –Apply-.

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Step 5. Create an MSC.Laminate Modeler Material

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reference angles.
Laminate Modeler : Create / LM_Ply / Add.
Select Mat_1 as the LM_Material.
Enter Surface 1 as the Select Area.
Enter [1250 0 1250] as the Start Point.
Enter Coord 0.1 for the Reference Direction. (Along X-direction)
Enter 0 for the Reference Angle.
Click –Apply-.

Once the start point is entered the application direction is entered automatically.

Angle.
Click –Apply-.
Enter 90 for the Reference Angle.
Click –Apply-.
Enter 135 for the Reference Angle.
Click –Apply-.

For the 3rd ply keep
all the input the same,
except change the ref.
angle to 90.

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Step 6. Create Plies Using MSC.Laminate Modeler (Cont.)

For the 2nd ply keep
all the input the same,
except change the ref.
angle to 45.

For the 4th ply keep
all the input the same,
except change the ref.
angle to 135.

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(Cont.)

times, giving a layup with 24 plies.
Laminate Modeler : Create / LM_Layup / Add.
Click Layup Definition.
Stack ply 1 through 4, in order. Do this six times, giving a 24 ply layup.
Click OK.
Click –Apply-.
Click OK to accept.

Step 7. Create MSC.Laminate Modeler Layup

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Do not use any offsets. Use standard element type, and default tolerance.

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application region, etc.) using MSC.Laminate Modeler.
Laminate Modeler : Show / LM_Ply / Graphics.
Select Ply_2.
Click –Apply-.

Select other plies to check the fiber direction and application region.

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24.
Click –Apply-.
Click Reset Graphics.

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Can select one ply/lamina at a time to view it individually.

Step 9. Check Layup Using MSC.Laminate Modeler

create a uniform temperature lbc for the entire model. This is used to simulate what happens when the material is cooled to room temperature, after curing at 55 degrees above ambient temperature.
Loads/BCs : Create / Temperature / Element Uniform.
Enter cooling_temp as the New Set Name.
Select 2D as the Target Element Type.
Click Input Data.
Enter –55 for the Temperature.
Click OK.
Click Select Application Region.
Select Surface 1.
Click Add.
Click OK.
Click –Apply-.

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apply displacement constraint LBCs.

Step 10. Apply Uniform Temperature in MSC.Patran (Cont.)

lbcs are for the displacement constraints. The model must be restrained from any rigid body motion, but must not be hindered from undergoing free expansion.
Loads/BCs : Create / Displacement / Nodal.
Enter fixed_nodes as the New Set Name.
Click Input Data.
Enter <0,,0> for the Translations.
Click OK.
Click Select Application Region.
Select FEM as Geometry Filter.
Select Node1 and Node 257.
Click Add.
Click OK.
Click –Apply-.

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the Translations.
Click OK.
Click Select Application Region.
Select FEM as Geometry Filter.
Select Node 144.
Click Add.
Click OK.
Click –Apply-.

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Step11. Create Nodal Displacement Constraints in MSC.Patran (Cont.)

Model / Full Run.
Click Subcases.

Step 12. Run the Analysis Using MSC.Nastran

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Ply Stresses
Click OK.
Click Apply.
Click Cancel.

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Step 12. Run the Analysis Using MSC.Nastran (Cont.)

File.
Select springback.xdb.
Click OK.
Click Apply.

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Step 12. Run the Analysis Using MSC.Nastran (Cont.)

/ Deformation.
Select SC1 DEFAULT, A1 Static Subcase.
Select Displacements, Transnational.
Click Apply.
Also, can plot fringe for stress results.

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It has been simulated what happens when a composite cools from curing temperature to room temperature. Because of the orthotropic thermal and mechanical properties the model distorts.
There is a different shape than the one that was made in the mould!

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model for the springback. This can be done using an MSC.Patran Utility.
Utilities : Results / Result Utilities.
Click OK to accept the disclaimer.

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The model can be bent back into shape, but that may be unwise because of the stresses it may cause, or it may simply prove to be impossible to get it back into the correct circular shape.
 
This severe problem can be solved using an MSC.Patran Utility.

Can continue using this database to complete this workshop. In practice it is advisable to work with a copy of the database, because the changes made in the next step cannot be undone, they are permanent.

25-(NON-LAYERED).
Click Close.
Enter –1.0 for Deformation Scale Factor/Magnitude.
Uncheck Auto Execute.
Select all the nodes.
Click Apply.
Click Cancel.

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The nodes have been permanently moved in the direction opposite( a factor of –1.0 was used) to the displacements obtained from the analysis, but the distance they were moved is the same as for the displacements. This is the shape that is needed !

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Step 14. Compensate the FE Model for the Springback (Cont.)

The model will change shape.

/ Export Options.
Check IGES.
Click –Apply-.
Laminate Modeler: Create / LM_Layup / Add.
Click –Apply-.











File / Close to close the database.

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This basically just re-applies the layup with no changes. The reason this is done is to export the mould shape.
 
Investigate that the file “springback_mould.igs” is created in the working folder.  

This shape is different from the shape that the product is to have in the end. Given the curing temperature of 55, the model will distort into the correct shape when cooled to room temperature.

Do not open a new layup file. Continue working with the existing file. Otherwise, it will not be possible to export an IGES file.

Step 15. Export the Compensated FE Model

OK.
Click OK.

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Step 16. Create a New MSC.Patran Database

model with offset nodes to give corrected initial shape.
File / Import.
Select IGES as the Source.
Select springback_mould.igs.
Click –Apply-.

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were imported. There are 960 of them.
Mesh the geometric surfaces.
Equivalence to connect the elements.
Create temperature and displacement boundary conditions.
Create MSC.Patran material properties by reading material.ses.
Create an MSC.Laminate Modeler material property.
Create four MSC.Laminate Modeler plies.
Create an MSC.Laminate Modeler layup.
Run an analysis using MSC.Nastran.
The shape from the analysis should look like the shape of the surface created by read the session file springback_geom.ses, at the beginning of this workshop.

Step 18. Optional Task