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Inventor 2014 problems by Linddana

12 REPLIES 12
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Message 1 of 13
re
Explorer
900 Views, 12 Replies

Inventor 2014 problems by Linddana

Problem 1 – Connecting parts in FEM

 

Rote: Environments --> Stress Analysis --> New Simulation --> Contacts --> Tolerance

This feature is not working. If you change the tolerance from the standard 0,100 mm to for example 2 mm it dosen’t make any difference in the outcome of your FEM simulation. The parts with a separation of 2 mm or less are not tight together.

This is a problem when you are working with an assembly where there are gabs between the parts that will be welded when the product is made in the workshop. In our company we have decided not to use welding in inventor.

 

Problem 2 – FEM in Large assembly

 

The stress analysis is not working in large assemblies. This is a problem we have been dealing with for a long time. Therefore we do everything we can to simplify the assembly which needs to be calculated. We do that by deleting unimportant parts and filling out all holes in the assembly.

The problem is that the mesh generation stops loading when 80-90% done. And when you try’s to cancel you can’t and the program is stuck. Then if you try to close inventor it crashes (Report has been send). The problem occurs when working with an assembly with more than 10-20 parts depending on the complexity of the parts.

In a complete machine we have between 200 and 800 parts and the stress analysis is therefore sometimes impossible.

 

Problem 3 – Making faces over bends in sheet metal

 

You can cut over bend but you cannot face over bend. If you want to make a face over a bend you will have to do it in flat pattern. And when you do it in flat pattern the new face will not occur in when you fold the part again and you cannot see the outcome of your change (The method we are using at the moment).

We have tried using the unfold and refold feature to make the face in the bend but when we do it inventor makes the “Indicates a partially failed operation” error. If we accept the change anyway we have some problems with the reference plane when we refold and the sheet metal part loses it’s originally origin.

 

I didn’t know where to go with these problems so I chose to post them here.

12 REPLIES 12
Message 2 of 13
JDMather
in reply to: re

#1 You have not indicated what version of Inventor you are using.

 

#2 Would need sample data set.

 

#3 Attach the *.ipt file here that returns error, "Indicates a partially failed operation” error."


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Message 3 of 13
re
Explorer
in reply to: JDMather

#1 The current version is attached

#3 I cannot attach the file in this space because it’s classified. In this case I will need an email address from you.

Message 4 of 13
JDMather
in reply to: re

#1.  What type of Contacts do you have active (it sounds like you do not want Bonded)?


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Message 5 of 13
re
Explorer
in reply to: JDMather

I want them to be like if they were welded together in real life. And we weld gabs up to 0.6 mm. The problem is that I don’t want to make a manual contact every time. Therefor I want to be able to set the tolerance to 0.6 mm.

 

In this case i would say that bonded is the right one to chose.

Message 6 of 13
JDMather
in reply to: re

If you want Bonded and you set the default to span any size gab - then the results should be the same.

 

In effect, you have simplfied the model for analysis.

 


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Message 7 of 13
re
Explorer
in reply to: JDMather

Can you explain how to set the span to any size gab?

 

And wouldn’t the simulation be like a brick when everything is tight together? I mean if I have a gab on 1000 mm I don’t want it to be tight together.

Message 8 of 13
JDMather
in reply to: re

These two sentences don't make any sense -

 

 If you change the tolerance from the standard 0,100 mm to for example 2 mm it dosen’t make any difference in the outcome of your FEM simulation. The parts with a separation of 2 mm or less are not tight together.

 

It sounds like you are changing the Default interpretation for Automatic Bonded Contacts.  A 2mm gap should not be interpreted as Bonded - that doesn't make logical sense to me?  It sounds to me like you should be changing the type of Contact, not the tolerance for interpreting the default Bonded Contact.  What book are you using to learn Inventor FEA?

 

Then second sentence, I think you meant to write, "Parts with a separation of 0.2mm or greater are not tight together."

 

It sounds like you should be using the Frame Generator FEA.

Inventor is not going to calculate weld strengths - it is limited to isotropic materials.

 

Edit:

The more I go back and read this I do not understand what you are trying to do.

I recommend that you have your VAR come in and look at your processes and needs.

 

#3 sounds like an easier problem to solve - can you attach more information here?


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Message 9 of 13
re
Explorer
in reply to: JDMather

I have made an example for you.

 

In real life the 3 parts are welded together. We need the 0.6 mm gabs between the parts to “absorb” the tolerances.

 

Therefore we need the FEM simulation to act like the 3 parts are welded together (calculating the assembly as one part) without the need to actually make contact between the parts in the FEM manually (by removing the gab or making a derived part and then extruding the 3 parts together where the welding will be).

 

Try to simulate the Test.iam in Stress analysis and hopefully you will see what I mean.

 

I hope that you can help me solve the problem.

Message 10 of 13
re
Explorer
in reply to: re

Will you please look at my example?

Message 11 of 13
JDMather
in reply to: re

You default contract tolerance was set to less than your actual gap.

Set it to 1 mm (or something slightly more than 0.6mm) and resolve for the Contacts (or you can add them manually).

 

When I made the change - it worked as expected.

 

 


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Message 12 of 13
JDMather
in reply to: JDMather

I suspect that whatever you have bolted in those 4 holes would restrict the bending of that plate.

You might add a Split Face the size of the mating part and a Frictionless constraint.


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Message 13 of 13
nmt
Advocate
in reply to: re

 

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