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StuartRogers
Posts: 25
Registered: ‎03-07-2012
Accepted Solution

Missing Eigenvalues execution problem: 3240

556 Views, 7 Replies
10-02-2012 06:32 AM

Hi,

 

I am trying to carry out a modal analysis or a simple truss bridge.

 

When carrying out the modal analysis I get the message: 'Number of missing eigenvalues found = 3'

 

If I select cancel (to search for all modes), I get the error message 'execution problem: 3240'. Then ROBOT crashes.

 

I have ticked the 'Sterm check' button for the modal analysis.

 

I have allowed a very large number of iterations (30000).

 

Is there anything else I can / should be doing?

 

Selecting 'No' on the 'Number of missing eigenvalues found = 3' message box runs the analysis fine. What is the implication for not searching for missing eigenvalues?

 

Thank you for your help.

 

Regards,

 

Stuart

 

 

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Product Support
Rafal.Gaweda
Posts: 5,595
Registered: ‎04-26-2010

Re: Missing Eigenvalues execution problem: 3240

10-02-2012 06:35 AM in reply to: StuartRogers

Turn off Sturm Check in Modal analysis.

If it does not help please send us model.



Rafal Gaweda
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Contributor
StuartRogers
Posts: 25
Registered: ‎03-07-2012

Re: Missing Eigenvalues execution problem: 3240

10-02-2012 07:10 AM in reply to: Rafal.Gaweda

Turning the Sterm check off worked. Thank you.

 

out of interest why would the Sturm check algorithm cause ROBOT to crash while checking for skipped eigenvibrations?

 

Regards,

 

Stuart

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Product Support
Rafal.Gaweda
Posts: 5,595
Registered: ‎04-26-2010

Re: Missing Eigenvalues execution problem: 3240

10-02-2012 07:31 AM in reply to: StuartRogers

PLease send us model to check.

It should not crash.



Rafal Gaweda
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Contributor
StuartRogers
Posts: 25
Registered: ‎03-07-2012

Re: Missing Eigenvalues execution problem: 3240

10-04-2012 01:18 AM in reply to: Rafal.Gaweda

Rafal,

 

Please find attached the ROBOT model which crashes when I have the 'Sturm Check' box ticked.

 

It runs fine when the 'Sturm Check' box is not ticked.

 

Regards,

 

Stuart

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Product Support
Rafal.Gaweda
Posts: 5,595
Registered: ‎04-26-2010

Re: Missing Eigenvalues execution problem: 3240

10-04-2012 01:54 AM in reply to: StuartRogers

With Sturm check you can caclulate 97 modes without any problems.

Why do you need more? In fact first 4 modes are global modes, I guess the most interesting ones.



Rafal Gaweda
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Contributor
StuartRogers
Posts: 25
Registered: ‎03-07-2012

Re: Missing Eigenvalues execution problem: 3240

10-04-2012 02:19 AM in reply to: Rafal.Gaweda

Good point!

 

I was trying to achieve 90% MEM participation in each direction and we are interested in frequencies upto 33Hz. Infact 97 modes should be fine.

 

Regards,

 

Stuart

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Product Support
Rafal.Gaweda
Posts: 5,595
Registered: ‎04-26-2010

Re: Missing Eigenvalues execution problem: 3240

10-04-2012 02:56 AM in reply to: StuartRogers
 

I was trying to achieve 90% MEM participation in each direction

 

33 modes is enough

 

and we are interested in frequencies upto 33Hz. Infact 97 modes should be fine.

 

101 modes with sturm check and press NO as answer for enlarging number of modes... or turn off sturm check.

 

 



Rafal Gaweda
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