basic problem with MSC.Nastran input deck

[Nullstab]

Hallo,

I have a basic problem with my Nastran input deck (picture 1) (.dat-file). It represents a simple linear static problem with three rod elemnts. Nastran can process this input file and a result file (.xdb) is created. As a next step I edited the grid and the element section in order to change structure (truss) (picture 2, second post). Now Nastran cannot process the input file anymore, it does not carry out an analysis. All I did was to change the structure and to adjust the force and support section a little bit. I do not understand that because I am convinced that there are no errors in the changes I made to the input deck.

 11:22:38  MSC Authorization Information - Checkout Successful (1016, 0)
 11:22:38  -------------------------------------------------------------
 11:22:38  Acquired 1 license for MSC.Nastran from license server on host license2.lrz.de


Beginning bulk data processing using the IFPStar component.
For more information on IFPStar, please see KB article KB8019200
on our support pages, at [URL unfurl="true"]http://simcompanion.mscsoftware.com.[/URL]

 11:22:39  59 records read from JID file "c:/__rechnen/kleines_stabwerk.dat"
 11:22:39  Analysis started.
 11:22:39  Geometry access/verification to CAD part initiated (if needed).
 11:22:39  Geometry access/verification to CAD part successfully completed (if needed).
 11:22:39  15 records read from JID file "c:/__rechnen/kleines_stabwerk.dat"
 11:22:39  NSEXIT: EXIT(0)
 11:22:39  Analysis complete  0
AssignProcessToJobObject failed, error code = 5.
  Error message is "Zugriff verweigert".
Reported CPU times may be incomplete.
Real:        9.920 seconds ( 0:00:09.920)
User:        0.468 seconds ( 0:00:00.468)
Sys:         0.124 seconds ( 0:00:00.124)
MSC.Nastran finished Wed Oct 22 11:22:39 MS 2014

Can You help me with this problem? Thank You for Your help!

Michael

 

[Nullstab]

This is picture 2.

 

[Naffoussi]

What is the error reported in the F06 file?

Seif Eddine Naffoussi, Stress Engineer

http://www.Innovamech.com

33650 Martillac – France

 

[jotunn]

I don't know what the error is or means (I don't use MSC)...but you have several issues with both models (I'm surprised the first one solved...you must be using AUTOSPC or similar).

A couple hints:
•ROD elements don't support bending
•Make sure you're fully constrained (e.g. no rigid body motion)

Your first model is not constrained in RX (4 direction)...even if you add 4 direction SPC to nodes 1 THRU 3, it will not matter since you're using RODS.

You second model is not constrained in RY (5 direction). Same as above, even if you add 5 direction SPC to nodes 1 THRU 2, it ain't gonna matter. The second model also has another bending degree of freedom you need to address which is rotation about CROD 6 (remember....RODS don't support bending...basically your truss is free to bend in half).

 

[Nullstab]

Dear guys,

thank you for your answers. As I am a beginner in MSC.Nastran I made one of the most basic mistakes: I made use of the tab-key while editing the input file. Now I know that this is absolutely forbidden and re-edited the file using the space-key only. Nastran is able to solve both models now.

@jotunn:
I can't see a problem with the models as both are statically overdetermined. The SPCs are constraining all translational dofs. You are right that I should have restricted the translational dofs in the grid definition. But as there are no loads in z-direction this should not be a problem (and Nastran accepts this input file).

Michael

 

[hezhj2000]

You need to open the f06 file, search 'fatal', and paste the fatal error message Nastran reports.