Welcome to the forums. Please post in English or French.

You are not logged in.

#1 2020-06-12 00:12:03

KevinTse
Member
From: Winnipeg, MB, Canada
Registered: 2020-05-13
Posts: 11

Error: The solution of the linear system is too vague

Hi all, I have build a 1x3 frame model, I compound each elements and set restrains at the 3 ends. However when I run the analysis it always show the error that"the solution of the linear system is too vague", only I constrained all nodes can solve this error, but it will cause no deflections. I felt confused.
The setting in mesh is in the attatchments.

Here are my codes in Aster study:

DEBUT(LANG='EN')

mesh = LIRE_MAILLAGE(FORMAT='MED',
                     UNITE=20)

model = AFFE_MODELE(AFFE=_F(MODELISATION=('POU_D_E', ),
                            PHENOMENE='MECANIQUE',
                            TOUT='OUI'),
                    MAILLAGE=mesh)

elemprop = AFFE_CARA_ELEM(MODELE=model,
                          POUTRE=_F(CARA=('HY', 'HZ'),
                                    GROUP_MA=('Structure', ),
                                    SECTION='RECTANGLE',
                                    VALE=(50.0, 140.0)))

timber1 = DEFI_MATERIAU(ELAS=_F(E=110000000.0,
                                NU=0.45))

fieldmat = AFFE_MATERIAU(AFFE=_F(MATER=(timber1, ),
                                 TOUT='OUI'),
                         MODELE=model)

load = AFFE_CHAR_MECA(DDL_IMPO=_F(DRX=0.0,
                                  DRY=0.0,
                                  DRZ=0.0,
                                  DX=0.0,
                                  DY=0.0,
                                  DZ=0.0,
                                  GROUP_NO=('Edge1', 'Edge2', 'Edge3')),
                      MODELE=model)

load0 = AFFE_CHAR_MECA(FORCE_NODALE=_F(FX=100000.0,
                                       GROUP_NO=('Load_conn1', )),
                       MODELE=model)

reslin = MECA_STATIQUE(CARA_ELEM=elemprop,
                       CHAM_MATER=fieldmat,
                       EXCIT=(_F(CHARGE=load),
                              _F(CHARGE=load0)),
                       MODELE=model)

IMPR_RESU(FORMAT='MED',
          RESU=_F(RESULTAT=reslin),
          UNITE=2)

FIN()


Attachments:
5.png, Size: 80.56 KiB, Downloads: 55

Offline

#2 2020-06-12 11:10:29

sameer21101970
Member
Registered: 2019-09-06
Posts: 246

Re: Error: The solution of the linear system is too vague

reduce load to 100 and see you are getting same message

Offline

#3 2020-06-12 21:16:08

KevinTse
Member
From: Winnipeg, MB, Canada
Registered: 2020-05-13
Posts: 11

Re: Error: The solution of the linear system is too vague

sameer21101970 wrote:

reduce load to 100 and see you are getting same message

No, it post the same error.

Offline

#4 2020-06-12 22:38:24

AsterO'dactyle
Administrator
Registered: 2007-11-29
Posts: 342

Re: Error: The solution of the linear system is too vague

Hello,

The problem is not well posed

Check your parameters: Young modulus and  section of your beams.
And careful: NU=0.45 is near the incompressible limit => volumetric locking


Code_Asterの開発者

Offline

#5 2020-06-13 06:13:12

sameer21101970
Member
Registered: 2019-09-06
Posts: 246

Re: Error: The solution of the linear system is too vague

Absolutely right. NU - reduce it or check your material properties.

For InCompressible material which material law will apply - in Code Aster. Any Hint.

Offline

#6 2020-06-18 07:31:40

KevinTse
Member
From: Winnipeg, MB, Canada
Registered: 2020-05-13
Posts: 11

Re: Error: The solution of the linear system is too vague

AsterO'dactyle wrote:

Hello,

The problem is not well posed

Check your parameters: Young modulus and  section of your beams.
And careful: NU=0.45 is near the incompressible limit => volumetric locking


Okay, I solve it now, maybe is that and I set too many elements in mesh at first.

Offline

#7 2020-06-19 17:57:06

AsterO'dactyle
Administrator
Registered: 2007-11-29
Posts: 342

Re: Error: The solution of the linear system is too vague

Hello

"too many elements", no, but check the quality of your mesh, for instance, aspect ratio in the Mesh module of salome_meca


Code_Asterの開発者

Offline

#8 2020-09-11 15:34:28

frdiego
Member
Registered: 2019-02-21
Posts: 1

Re: Error: The solution of the linear system is too vague

I had the same problem and I solved simply changing from POU_D_E in AFFE_MODELE to POU_D_T.

I had very small element size compared with the diameter of the beam, I guess Euler beam model can't represent the flexure properly, changing the Timoshenko beam it worked.

Offline