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

You are not logged in.

#1 2013-10-21 14:31:06

anders82
Member
Registered: 2013-10-21
Posts: 4

Stresses from Coque_3D ?

Hi All,

I am new here (and to Salome-Meca/Code_Aster). My intentions are to use the package for detailed FE calculations of tubular joints with regards to stress concentration factors used for fatigue life assessment.

Currently I am trying to determine how to evaluate the stresses in the quadratic shell elements (Coque_3D), as this is essential to my task at hand.

My starting point is the simple tutorial found here; a simply supported plate of dimensions 1.000x1.000x0.001m. The model is meshed with quad8 elements.

My command file can be seen below. This enables me to plot/preview deformations, but not stresses. I have tried various approaches, from different tutorials or examples found on the web (e.g. here), but none have worked so far.
I am using Salome-Meca 2013.2 with Code_Aster 11.4 (The newest package downloadable from www.code-aster.org).

My question/plea is then if anyone has any constructive input to the approach I need to take ?

DEBUT();
th = 0.001;


steel=DEFI_MATERIAU(ELAS=_F(E=2.100e11,
                            NU=0.30,
                            RHO=7850,),);

initMesh=LIRE_MAILLAGE(FORMAT='MED',
                       INFO=1,);

cocMesh=CREA_MAILLAGE(MAILLAGE=initMesh,
                      MODI_MAILLE=_F(TOUT='OUI',
                                     OPTION='QUAD8_9',),);

intModel=AFFE_MODELE(MAILLAGE=initMesh,
                     AFFE=_F(TOUT='OUI',
                             PHENOMENE='MECANIQUE',
                             MODELISATION='3D',),);

cocModel=AFFE_MODELE(MAILLAGE=cocMesh,
                     AFFE=_F(TOUT='OUI',
                             PHENOMENE='MECANIQUE',
                             MODELISATION='COQUE_3D',),);

shellch=AFFE_CARA_ELEM(MODELE=cocModel,
                       COQUE=_F(GROUP_MA='shell',
                                EPAIS=th,
                                VECTEUR=(1,0,0,),
                                COQUE_NCOU=1,),);

material=AFFE_MATERIAU(MAILLAGE=cocMesh,
                       AFFE=_F(TOUT='OUI',
                               MATER=steel,),);

Load=AFFE_CHAR_MECA(MODELE=cocModel,
                    DDL_IMPO=(_F(GROUP_MA='Linex0',
                                 DX=0,
                                 DZ=0,),
                              _F(GROUP_MA='Liney0',
                                 DY=0,
                                 DZ=0,),
                              _F(GROUP_MA='Linex1',
                                 DZ=0,),
                              _F(GROUP_MA='Liney1',
                                 DZ=0,),),
                    PRES_REP=_F(GROUP_MA='shell',
                                PRES=-1000,),);

RESU=MECA_STATIQUE(MODELE=cocModel,
                   CHAM_MATER=material,
                   CARA_ELEM=shellch,
                   EXCIT=_F(CHARGE=Load,),
                   OPTION='SIEF_ELGA',);

RESU=CALC_CHAMP(reuse =RESU,
                RESULTAT=RESU,
                TOUT='OUI',
                CONTRAINTE=('SIGM_ELGA','SIGM_ELNO',),);

proj_res=PROJ_CHAMP(PROJECTION='OUI',
                    RESULTAT=RESU,
                    MODELE_1=cocModel,
                    MODELE_2=intModel,);

IMPR_RESU(FORMAT='MED',
          RESU=_F(RESULTAT=proj_res,),);

FIN();

Offline

#2 2013-10-21 15:46:14

jeanpierreaubry
Guru
From: nantes (france)
Registered: 2009-03-12
Posts: 3,570

Re: Stresses from Coque_3D ?

hello

with a pressure stresses in the neutral fiber are null
this adds calculation for the top face

RESU=CALC_CHAMP(
	...................
);

#on the top face	
resu2=POST_CHAMP(
	RESULTAT=RESU,
    EXTR_COQUE=_F(
        NUME_COUCHE=1,
        NIVE_COUCHE='SUP',
        NOM_CHAM=('SIGM_ELNO',),
    ),
);

#invariants
resusup=CALC_CHAMP(
    RESULTAT=resu2,
    CRITERES=('SIEQ_ELNO','SIEQ_NOEU',),
);

jean pierre aubry

Offline

#3 2013-10-21 20:14:02

keeswouters
Member
From: kuringen
Registered: 2007-12-01
Posts: 144
Website

Re: Stresses from Coque_3D ?

Hoi

that example is for pre C-A11.4.
These may be used with C-A11.X, depending on what postprocessor you like [postpro or paravis]:

http://www.caelinux.org/wiki/index.php/ … /plotcoq3d

or

http://www.caelinux.org/wiki/index.php/ … q3dparavis

Last edited by keeswouters (2013-10-21 20:15:11)


kind regards - kees
--
I a parallel univers the laws of mechanics may be different.

Offline

#4 2013-10-21 23:00:43

Jacopo
Member
From: Colle di Val d'Elsa, Italy
Registered: 2008-02-05
Posts: 564

Re: Stresses from Coque_3D ?

Attached some file that can help you.

Ciao
Jacopo


Attachments:
SHELL_OUTPUT.zip, Size: 9.04 KiB, Downloads: 198

Salome-Meca 2017.02 (Intel Xeon 8 Core x 2 RAM 32GiB) Ubuntu 16.04 LTS

Offline

#5 2013-10-22 09:04:40

anders82
Member
Registered: 2013-10-21
Posts: 4

Re: Stresses from Coque_3D ?

Thank you all for the helpful replies, they are muchly appreciated!

@keetwouters:

I have used post-pro, but only because the first tutorial I tried used that, I have no preference as such...

I have tried to follow the example you set forth in http://www.caelinux.org/wiki/index.php/ … /plotcoq3d, but generating the geometry through Salome-meca. I have furthermore disabled some of the more advanced functions (variable thickness, multiple load cases).

I am able to run the model and import the results into post-pro, but then for some reason, I am only able to plot the results on the edges (See attached: PostPro.png - Note how I have three groups on my mesh, the two edges for BCs, and then the shell, but in post pro only the two edge groups remain). I am not able to plot results onto the wireframe mesh, or onto the surface.

Any ideas what I may have done wrong, or why I experience this issue?

/BR
Anders

Last edited by anders82 (2013-10-22 09:05:00)


Attachments:
PostPro.png, Size: 141.51 KiB, Downloads: 226

Offline

#6 2013-10-25 09:05:32

anders82
Member
Registered: 2013-10-21
Posts: 4

Re: Stresses from Coque_3D ?

I figured it out. Due to my inexperience with the software, I didn't realize that I needed to specifiy result files for 81 and 82 as well.

Once again, thank you all for the input and help.

/BR
Anders

Offline

#7 2013-10-25 10:34:59

keeswouters
Member
From: kuringen
Registered: 2007-12-01
Posts: 144
Website

Re: Stresses from Coque_3D ?

Hoi Anders

I figured it out. Due to my inexperience with the software, I didn't realize that I needed to specifiy result files for 81 and 82 as well.

That should be noticed by a copy error in the *.mess file.
Postpro is not available anymore in Salome7.X. So paraviz will be the future I presume.


kind regards - kees
--
I a parallel univers the laws of mechanics may be different.

Offline