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RSA - Force results

Experimenter
Experimenter

Hello everybody!!

I'm performin a response spectrum analysis on a vertical pressure vessel supported by 3 legs subjected to seismic load for a nuclear plant. I need to define the BASE LOAD for each legs but I cannot extract the FORCE from the result database despite I having requested them in the input file...

Probably is NX Nastran bug..Someone could help me? Any tricks to overcome the problem?

Thank you in advance!!

7 REPLIES 7

Re: RSA - Force results

Siemens Legend Siemens Legend
Siemens Legend

What kind of solution sequence you are trying ? Did you checked f06 whether it is successfully solve. Please post dat/f06 please

Re: RSA - Force results

Experimenter
Experimenter

I need to define the foundation loads at leg base: usually (simply static analysis) I extract them using a freebody - iterface load on the concerned nodes.

But when I try this after RSA no force value are available, even if I request them  (balance force, equilibrium force, ext..) in NX Nastran input file..please find here enclosed .dat and the .f06 file.

Thank you in advance.

Pietro, 

Re: RSA - Force results

Phenom
Phenom

everything modelled with solid elements !!! wow !! Must be a hell of a good reason behing such modelling

not much time looking at detail but 1st Qs

  1. why is rbe2 711910 not attached directly to the leg pads? Why these "double" RBE2s?
  2. how is the CONM2 attached to the struture?

 

Production: NX.CAE 10.0.2.6
Development: VB.NET (amateur level !)

Re: RSA - Force results

Experimenter
Experimenter

Smiley LOLSmiley LOLSmiley LOL

For the solid model unfortunatly is a requirement of the Client (Nuclear Plat), and the Client is always a sufficient reason!! For the other questions please find the reply in  the following:

 

  1. R : Simply I suppose that it's the better whay to simulate le connection with the exitation mass...
  2. R: it is the Exitation mass necessary for response spectrum analysis.

Re: RSA - Force results

Phenom
Phenom

Well I learnt something today as far as industry specific modelling - Glad I asked

 

so which software are you using to do your reps. sim. Is this equivalent to a Nastran SOL111 (I only SEMODES for the SOL)?

 

1. Not really . Could have attached the RBE2 for the exitation mass direcclty to all the pads. But that's a secondary point!

2. Should the seismic mass not attached to the RBE2 then ? I thought the seismis mass approach was "old school"

Production: NX.CAE 10.0.2.6
Development: VB.NET (amateur level !)

Re: RSA - Force results

Gears Phenom Gears Phenom
Gears Phenom

In example dat file I see analysis title SEMODES it is SOL 103 - it calculates only normal modes/eigenvalues. There are no force/stress results in this solution sequence.

Re: RSA - Force results

Experimenter
Experimenter

For RSA NX Nastran vs - 11.0.2 has been used. I confirm that SEMODES provides stress results, for your reference please see Examples N°19 in FEMAP.

The problem is that the solver give me only element stress but not nodal forces...