×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Output Mass and Stiffness matrices from NASTRAN?

Output Mass and Stiffness matrices from NASTRAN?

Output Mass and Stiffness matrices from NASTRAN?

(OP)
I make a simple beam model in which only stiffness and mass properties are attributed to the beams.
I would like to extract the mass and stiffness matrices for this model. How can I do this?
If possible I would like to have this data available in the F06-file?

RE: Output Mass and Stiffness matrices from NASTRAN?

It has been a while since I have done this, but I believe you will need to make a "dummy" run to print out the solution rigid format by putting DIAG 14 in your executive control deck.  Once you locate the matrices that you want to print out, you will need to place a rigid format ALTER in the executive control, followed by a MATGPR statement (there is a certain format that you need to specify the MATGPR statement that you will need to get from the NASTRAN reference manual).  The MATGPR will allow you to print out the global stiffness and mass matrices, KGG and MGG, into your .F06 or .PCH file.

pj

RE: Output Mass and Stiffness matrices from NASTRAN?

(OP)
Thanks a lot pj,

It is very helpful.

This is how I proceeded to get the desired results. Please comment on it if you think I am not exactly on the right track with what I want to achieve.

From the solution sequence (DIAG 14) I found the first DMAP module that could give me results on MGG and KGG to be SEMODES.



DMAP-DMAP INSTRUCTION                                                                                                          
      NO.                                                                                                                           
       1      SUBDMAP SEMODES $ SOL 103 - SUPERELEMENT NORMAL MODES                           
       2      $  IFP, PHASE0                                                                  
       2      TYPE DB AXIC,PVT,BULK,GEOM1Q,TIMSIZ,K4JJ,YG,RMG,CASESX,USET0,GEOM1S,            
                      VIEWTB,GPSNTS,BGPDTVU,IBULK,EHT,EHTA,CASERS,PVTBC,EDOM,DRG,             
                      MEDGE,MFACE,GDNTAB,PELSETS,ELEMVOL,PVAL,ERROR,TEMPALL,ERRORG,           
              $  PHASE 1                                                                      
                      KJJ,MJJ,BJJ,USET,GOT,KAA,DYNAMICS,DYNAMIC,KGG,PCDBS,AGG,                

… ETC …





Then at line 63 I found an instruction containing the input (GPLS, USET0, SILS) and output data blocks (MGG, KGG) I need:




63            CALL PHASE1DR,                                                            
                                SLIST   ,EMAP    ,DIT     ,MATPOOLS,EDTS    ,                 
                                DYNAMICS,GEOM4S  ,EPTS    ,CASECC  ,MPTS    ,                 
                                CASES   ,GPLS    ,EQEXINS ,CASESX  ,CSTMS   ,                 
                                BGPDTS  ,SILS    ,ECTS    ,MAPS    ,PVTS    ,                 
                                        ,VGFS    ,GDNTAB  ,CONTACT ,DEQATN  ,                 
                                DEQIND  ,GPSNTS  ,ECTAS   ,MEDGE   ,EHT     ,                 
                                RMG     ,USET0   ,YG      ,SLT     ,ETT     ,                 
                                        ,EPTA    ,EHTA    ,SCSTM   ,PVTBC   ,                 
                                        ,        ,EQEXIN  ,        ,        ,                 
                                        ,        ,AG0     ,        ,        ,                 
                                        ,        ,        ,        ,        ,                 
                                DRG     ,        ,        ,        /                          
                                EST     ,GPECT   ,VELEM   ,KELM    ,KDICT   ,                 
                                MELM    ,MDICT   ,KJJ     ,MJJ     ,BJJ     ,                 
                                K4JJ    ,        ,        ,KGG     ,GM      ,                 
                                USET    ,KSF     ,KFS     ,KSS     ,        ,                 
    KAA     ,MPHVZ   ,LOO     ,        ,GOT     ,                 
                                KLL     ,LLL     ,ULL     ,DAR     ,MGG     ,                 
                                BGG     ,K4GG    ,MAA     ,        ,MR      ,                 
                                MLR     ,MLL     ,MRR     ,CMPHA   ,CMPHO   ,                 
                                CMLAMA  ,        ,GOQ     ,        ,MAR     ,                 
                                MEA     ,        ,BAA     ,K4AA    ,        ,                 
                                        ,        ,        ,        ,        ,                 
                                        ,        ,ESTL    ,ESTNL   ,AGG     ,                 
                                BTOPO   ,KMG     ,MMG     ,MSF     ,BMG     ,                 
                                BSF     ,K4MG    ,K4SF    ,        ,ORSEQ   ,                 
                                LRSEQ   ,VGFD    ,DITID   ,        ,        ,                 
                                        ,        ,        ,        ,        ,                 
                                        ,BK4ZZ   ,        ,        ,        /                 
                                APP     /ERROR   /LASTSEID/SOLTYP  /ALTRED  /                 
                                CYCLIC  /ADPTINDX/NLHEAT  /AERO    /RSONLY  /                 
                                LUSETS  /SEMG    /SEKR    /SELG    /SELR    /                 
                                SEMR    /FIXEDB  /MODACC  /INREL   /FSCOUP  /                 
                                NONLNR  /K6ROT   /AUTOSPC /TRUE    /EXTERSE /                 
                                PEXIST  /FALSE   /FALSE   /KDIFF   /FALSE   /                 
                                FALSE   /'      '/FLUIDSE0/0       $                          


… ETC …




I included the following DMAP alter in the executive control deck:

$
COMPILE SEMODES $
ALTER 63 $
MATGPR GPLS,USET0,SILS,MGG//'G' $
MATGPR GPLS,USET0,SILS,KGG//'G' $
$

This gave me the following results in the .f06 file:



0                MGG                                                                                                                
     POINT           VALUE     POINT           VALUE     POINT           VALUE     POINT           VALUE     POINT           VALUE  
                                                                                                                                    

 COLUMN           1 (           1-T1).
          1 T1  1.00000E+01

 COLUMN           2 (           1-T2).
          1 T2  1.00000E+01

 COLUMN           3 (           1-T3).
          1 T3  1.00000E+01

 COLUMNS           4 (           1-R1) THRU           6 (           1-R3) ARE NULL.

 COLUMN           7 (           2-T1).
          2 T1  2.00000E+01

 COLUMN           8 (           2-T2).
          2 T2  2.00000E+01

 COLUMN           9 (           2-T3).
          2 T3  2.00000E+01

…etc…

0                KGG                                                                                                                
     POINT           VALUE     POINT           VALUE     POINT           VALUE     POINT           VALUE     POINT           VALUE  
                                                                                                                                    

 COLUMN           1 (           1-T1).
          1 T1  1.05000E+08         1 T3  1.26940E+00         1 R2 -1.05000E+08         2 T1 -1.05000E+08         2 T3 -1.26940E+00
          2 R2 -1.05000E+08

 COLUMN           2 (           1-T2).
          1 T2  1.05000E+08         1 R1  1.05000E+08         1 R3  1.27365E+00         2 T2 -1.05000E+08         2 R1  1.05000E+08
          2 R3  1.27365E+00

 COLUMN           3 (           1-T3).
          1 T1  1.26940E+00         1 T3  3.50000E+05         1 R2 -1.27365E+00         2 T1 -1.26940E+00         2 T3 -3.50000E+05
          2 R2 -1.27365E+00

 COLUMN           4 (           1-R1).
          1 T2  1.05000E+08         1 R1  1.40000E+08         1 R3  1.53899E+00         2 T2 -1.05000E+08         2 R1  7.00000E+07
          2 R3  1.00831E+00

 COLUMN           5 (           1-R2).
          1 T1 -1.05000E+08         1 T3 -1.27365E+00         1 R2  1.40000E+08         2 T1  1.05000E+08         2 T3  1.27365E+00
          2 R2  7.00000E+07

 COLUMN           6 (           1-R3).
          1 T2  1.27365E+00         1 R1  1.53899E+00         1 R3  1.31253E+07         2 T2 -1.27365E+00         2 R1  1.00831E+00
          2 R3 -1.31253E+07



…etc…




I hope I am doing it right?
Thanks again,
Regards,

Onemorechance

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources