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Robot Structural Analysis

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Valued Mentor
tony.ridley
Posts: 652
Registered: ‎09-07-2011

Re: lifting the construction

04-23-2012 06:31 AM in reply to: mortel09

normally, just use the spreader on two sides, it will be stable for regular shaped geometry.  

 

 

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Valued Contributor
mortel09
Posts: 56
Registered: ‎01-31-2012

Re: lifting the construction

04-23-2012 06:35 AM in reply to: tony.ridley

we are not supposed to use spreader bars, but we have added a support in one of the corner were we have cross checked RX, RY and RZ. This worked with the instabilty in node 52 :smileywink:

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Mentor
Rafacascudo
Posts: 183
Registered: ‎05-16-2011

Re: lifting the construction

04-23-2012 02:42 PM in reply to: mortel09
Mortel09 ,No instabilities on your original model if you use the multi-threaded solver.
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Valued Contributor
mortel09
Posts: 56
Registered: ‎01-31-2012

Re: lifting the construction

04-24-2012 12:53 AM in reply to: Rafacascudo

the multi-threaded solver? I added a support in on of the corner so hold the rotation (RX, RY and RZ), will this be wrong to do?

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Valued Mentor
tony.ridley
Posts: 652
Registered: ‎09-07-2011

Re: lifting the construction

04-24-2012 01:38 AM in reply to: mortel09

My opinion is that if you have an instability in a model, using multi threaded to avoid it is un-conservative and not recommended.  The model should run fine on automatic before switching to multi thread. 

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Product Support
Rafal.Gaweda
Posts: 4,966
Registered: ‎04-26-2010

Re: lifting the construction

04-24-2012 01:55 AM in reply to: tony.ridley

Multithreaded solver may not report instabilities that's why it is recommended to find all model instabilities (esspecially of type 1 and 2) using different solvers.



Rafal Gaweda
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Valued Contributor
mortel09
Posts: 56
Registered: ‎01-31-2012

Re: lifting the construction

04-24-2012 02:02 AM in reply to: Rafal.Gaweda

Iam not sure what to do, I attached the file, when you hit calculations you get a warning of instability in node 52. What should i do?

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Valued Mentor
tony.ridley
Posts: 652
Registered: ‎09-07-2011

Re: lifting the construction

04-24-2012 02:08 AM in reply to: mortel09

it's type 3, so may just be large differernce in stiffness.  

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Valued Contributor
mortel09
Posts: 56
Registered: ‎01-31-2012

Re: lifting the construction

04-24-2012 02:11 AM in reply to: tony.ridley

Okei, thanks alot guys. The both of you have been really helpfull. I appreciate your help.

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Product Support
Artur.Kosakowski
Posts: 4,581
Registered: ‎12-17-2010

Re: lifting the construction

04-24-2012 02:58 AM in reply to: mortel09

Please check the displacements and rotations for case 1 (self-weight) before ignoring the reported instability.



Artur Kosakowski
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