frame analysis instability type 3

[Anonymous]

I have run a car chassis through frame analysis. I get a solver message  instability type 3 at node 108 in  direction RZ. When I change the beam model tolerance from 2 to 20 or 50 ul, I simply get the same message for a different node. Instability 3 occurs at nodes on very short members, I have removed these members and changed the design but I still get instability messages. I dont know if they are harmless warning messages or if the  results produced are incorrect. any advice would be appreciated.

[JDMather]

Attach your assembly here.

[Anonymous]

here is the chassis

[JDMather]

Not sure you are ready for analysis.

No parts?

[Anonymous]

here is the part

Edited by request
Discussion_Admin

[Anonymous]

and the rest

Edited by request
Discussion_Admin

[JDMather]

I think I  have this figured out.

Step 1 was to read the error messages.

So, I will want to find out which frame members were not converted to Beams.

And I will want to find Node 112.

[Anonymous]

hi, yes i see that the 3d sketch i was given has some lines only 2 mm long. when i used insert frame, these were not put in and the gap was so small i could not see anything missing. i am going to re do the sketch and i should be fine. but can i ask if i have curved frame members will frame analysis bring up the instability message again and should i ignore it

[JDMather · Accepted solution]

 Based on that information I turn on the visibility of the Node Lables

Right click on the Node 112 and select Find in Window.

 I see that there are several nodes in this area not conneced by rigid links.

The missing beams are associated with the curved frame members.

Manually add the missing Rigid Links where the curved frame members should connext to the rest of the beams.

Note that I changed the colors of the Rigid Links to red to make them stand out better for visibility.

[Anonymous]

i should be ok from now. thank you very much for your help

[JDMather]

Well I had trouble for some reason manually adding the Rigid Link to the left side.  On the right side it was easy.

I'll go back and check again if you continue to have trouble.

[Anonymous]

is it possible for you to remove the chassis and wishbone assembley and part from this page please

[JDMather]

I don't work for Autodesk - but I notified the forum moderator that you would like the files removed.

This is a public user-to-user forum, so be careful about what you share.

[Discussion_Admin]

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@Anonymous wrote:

is it possible for you to remove the chassis and wishbone assembley and part from this page please

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I edited these files out per your request

Thanks for the heads up @JDMather

Thanks
Discussion_Admin

[Anonymous]

thank you