© 2011 Autodesk

Autodesk Moldflow 2012 new feature

Non-zero displacement BC for Warp

How to use it in a good way??

© 2011 Autodesk

Allow use of a non zero displacement boundary conditions to simulate the effects of mounting a part during an assembly operation.

Key Features

Use forced displacement to consider the assembly-induced

Deformation and stress for linear elastic analysis

Available for midplane, dual domain and 3D

Limitation Should be use with small deflection analysis only

Non-zero displacement BC for Warp

© 2011 Autodesk

Non-zero displacement BC for Warp

Requirements Apply your constrains how you would like to constrain your mold

cavity to fit your final assembly position

Ensure rigid body motion is fixed Constrains created must fixed 6 degrees of liberty It can be part of your constrain

Fix nodes, or displacement at nodes Displacement values should consider the un-deformed

part as references Automatic correction on those constrains will be applied

on warp part to be equivalent to the constrains on theun-deformed part

© 2011 Autodesk

Example how to use it

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Example Bumber

For the example we use a simplified model

© 2011 Autodesk

Example

Two settings used:Non-zero displacement BC for Warp

USED

Non-zero displacement BC for WarpNOT USED

Comparison BC used and not used

Add regular BC to constrains the part for warpage analysis (6dof)

Part will be assembled at the car using this distances

© 2011 Autodesk

Example

Part deflect for the not assembled situation.

The BC simulate the assemble situation and the result shows the part deformation in this situation.

Due to the assembled situation, the component moves inward. It thus has a completely different shape form compared to the not assembled situation.

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Example: how to use it in more detail

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Workflow

Set 6DOFs and run an analysis without using the Non-zero displacement BC for Warp to get the shrinkage values. That will help to identify if the mold size is correct and you can see the deflection of your not assembled part.

Add the Non-zero displacement BC for Warp. Run the analysis again. The deflected shape show the deformation of the part as a combination of warpage in the assembled situation.

Assume that the bumper is in fully contact at the front of the car. Analysis 3 should take this into account.

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The following slides show results of the workflow.

© 2011 Autodesk

Example Bumber

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Part shrinkage in x-direction

More part shrinkage in x-direction

Side surfaces bow in-wards

This distance needs to be added to the mold to compensate for the shrinkage

Side surfaces now “parallel”

New deformation as a result of the attachment of the side surfaces.

© 2011 Autodesk

Example Bumber

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3Front of the bumper is fully constrained.

Side surfaces are still “parallel”.

Side surfaces bow a little bit more inwards

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Example Bumber

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This type of installation creates stress.

© 2011 Autodesk

Workflow use for

To show the deflection of a part. Use the assembly situation to show the deformation of a part. You can identify the amount of stress increase between the

origin deflection and the assembled situation.

That workflow can also be used if a specific measuring device is used to measure deflection.

This workflow should not be used for non-linear deflection.