help patran-nastran

[Silente24]

I hope you can help me. I have a piece of a very complicated frame to analyze, I put all forces agents and constraints where the frame is framed to the rest of the structure. when I go to do the analysis in nastran (I have 2010) reports the following erroe:
user fatal message 9050 (sekrrs)
^^ run ended two to overdose pivot ratios in matrix kll.
^^^ user action: constrain mechanisms with spci or suporti entries or specify param,bailout,-1 to
continue the run with mechanisms.

I know it's a problem of constraints, but I can't solve it, can someone give me a tip? ?

when I put a constraint, on the design to draw the bond with numbers next to it, are those degrees of freedom that has the point or are the degrees of freedom examined?

another thing, since patran 2010 I can't start nastran 2010, which executive file of nastran I have to link to with the configuration utility of patran 2010 and to what voice?

thanks in advance for the help! !

 

[Lorenzo_Z]

You have a labile model.
to solve the labile models (and then see which degree of freedom has the structure) you can use the param,bailout,-1 instruction that solves your problems with lability.
see attachment to understand how to insert it.
I would still try to make the isovincolata structure! !

the numbers you see indicated in patran are the degrees of freedom bound.

in the configuration utility to acommand2010 and alocalcommand2010 items specific the path of the nastran.exe file or mdnastran.exe present in the installation directory:

I for example have
c:\msc.software\md_nastran\bin\mdnastran.exe

I hope I have given you useful indications

 

[Silente24]

thanks lorenzo_z as always you can help me, I solved all the problems, I just need to understand how to incite the structure! !

 

[Lorenzo_Z]

look at the results with the param bailout. from the deformed you should understand what are the gdl to bind and that you miss. . .

Good job.. .

 

[Pakopako]

in addition to the excellent explanation of lorenzo, I would just add to pay a lot of attention with the bailout parameter, logically the results of an analysis with that parameter set to -1 are completely unreliable. ..so use it only to try to understand where there may be any lability, this is the simplest of cases, then logically the structure must be bound as it actually is, so you can not add fictitious constraints. ... also try the param k6rot and autospc, but attention as above, sometimes problems of lability can depend both on the improper use of some elements given by the poor knowledge of the same (e.g. the brick elements that do not have rotational gdl, and you restrict only the rotational gdl of these...), or as often happens by the improper use of mpc.
other check that I always recommend doing is a modal, if I echo abnormal mode shape especially at low frequencies, can be an excellent input for the search of lability.
I hope I was helpful, hello

 

[delphy90]

other check that I always recommend doing is a modal, if I echo abnormal mode shape especially at low frequencies, can be an excellent input for the search of lability.

I would like to take this opportunity to ask a question. assuming that the structure is labile, how can you understand which other constraints should be imposed by the modal analysis alone?

 

[Fabio.saccone]

Hello guys, I am a new member in this magnificent coimmunity; I'm trying to simulate a compression frame on patran (I use 2012) but it always gives me the same mistake.
user fatal message 9050 (sekrrs)
^^ run ended two to overdose pivot ratios in matrix kll.
^^^ user action: constrain mechanisms with spci or suporti entries or specify param,bailout,-1 to
continuous the run with mechanisms
Can someone help me? ?
:frown:

 

[marulanda]

param,bailout,-1, it only works if the structure is once labile so be careful, very agreeable with the speech to pay attention xche nn results are reliable.
you the most elegant way to study the constraints of a structure, I discover myself, is modal analysis, there is the undoubted advantage that allows you to find all the lability associated with the freq. null (e.g. three freq. zero = 3 lability).

Hi.