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#1 2019-06-19 13:53:52

phoenix22
Member
Registered: 2017-02-20
Posts: 25

E_Young varies by EPSI or DIVU

Dear all,
I wondered if it is possible to define an isotropic material with Tri-Linear elasticity: Modulus Young (E_Young) depends on volumetric deformation like that:
E_F=DEFI_FONCTION(
                NOM_PARA='EPSI',         #'DIVU'       
                VALE=(0.015,100e6,       
                      0.515,5.825e6,
              0.585,100e6    ),        
                PROL_DROITE='CONSTANT',
                PROL_GAUCHE='CONSTANT',);
However, there is the error attached, which I don't understand.
   ! <S> Exception user raised but not interceptee.                                 !
   ! The bases are fermees.                                                         !
   ! Type of the exception: error                                                   !
   !                                                                                !
   ! Erreur lors de l'interpolation de la fonction E_F sur la maille M61, il manque !
   ! le paramètre EPSI
Could anyone help me please?
Thank you and best regards,
Phoenix TRAN,

Last edited by phoenix22 (2019-06-19 14:29:49)

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#2 2019-06-19 14:21:14

phoenix22
Member
Registered: 2017-02-20
Posts: 25

Re: E_Young varies by EPSI or DIVU

I also modify with a loop for each iteration to obtain DIVU (or EPSI=EPSIxx+EPSIyy+EPSIzz) from the last calculation, but it has the same error.
How to obtain the DIVU for an interpolation?
About informations I'm very happy.
TRAN,

Attachments:
50x100_version1.zip, Size: 201.97 KiB, Downloads: 290

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#3 2019-06-19 15:04:35

Volker
Member
From: Chemnitz
Registered: 2016-05-23
Posts: 92

Re: E_Young varies by EPSI or DIVU

Hi, I think E an NU can't be a function of EPSI, only X, Y, Z and INST.
I would check the material model...
Kind regards Volker

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#4 2019-06-19 15:49:53

phoenix22
Member
Registered: 2017-02-20
Posts: 25

Re: E_Young varies by EPSI or DIVU

Thank you Volker,
  On the last page of the document U4.43.03: E_F = DEFI_FONCTION(NOM_PARA='NEUT1'....
that means E can illustrate as a function of NEUT1...
  On the document U4.31.02 (DEFI_FONCTION): NOM_PARA can be 'EPSI'
  On the document U2.04.05 (on page 34):
      MATEHY=AFFE_MATERIAU(MAILLAGE=MAIL,   AFFE=_F(TOUT='OUI',  MATER=MATERIAU,),
                                                 AFFE_VARC=_F(NOM_VARC='DIVU',  EVOL=DEFVHY,),);
I am not good at T.H.M model so I don't know how to use this NOM_VARC='DIVU' (as they did) in my modeling (just mechanical problem).

Any recommendations will be appreciated!
Kind regards Tran,

Volker wrote:

Hi, I think E an NU can't be a function of EPSI, only X, Y, Z and INST.
I would check the material model...
Kind regards Volker

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#5 2019-06-19 16:27:43

joanBO
Member
Registered: 2019-04-12
Posts: 16

Re: E_Young varies by EPSI or DIVU

Hi Tran,

Maybe this topic can help you. It shows how to apply a field into the nodes using "NOM_VARC":

/viewtopic.php?id=17518

In particular:

CHAM_GEO=CREA_CHAMP(TYPE_CHAM='NOEU_GEOM_R',    # Create the field of the geometrical coordinates
                OPERATION='EXTR',
                MAILLAGE=MAIL,
                NOM_CHAM='GEOMETRIE',);

YOUNG_Y = FORMULE(VALE='3.0E6*Y',                                # Create a function of youngs modulus depending on Y-coordinate
                 NOM_PARA='Y',);

CH_FONC=CREA_CHAMP(TYPE_CHAM='NOEU_NEUT_F',     # Create a field of functions (YOUNG_Y) per node 
                   OPERATION='AFFE',
                   MAILLAGE=MAIL,
                   AFFE=_F(
                   TOUT='OUI',
                   NOM_CMP='X1',
                   VALE_F=YOUNG_Y,),);

CHYOUNG=CREA_CHAMP(TYPE_CHAM='NOEU_NEUT_R',     # Evaluate the field CH_FONC with parameter field CHAM_GEO at each node
                   OPERATION='EVAL',
                   CHAM_F=CH_FONC,
                   CHAM_PARA=CHAM_GEO,);

# Now you should have a field representing the youngs modulus at each node
# the rest is described in U3.43.03

NU_F=DEFI_CONSTANTE (VALE=0.3);

E_F = DEFI_FONCTION (NOM_PARA='NEUT1', 
                     VALE= (-1.E-9, -1.E-9,
                            1.E+9, 1.E+9));
                            
MA=DEFI_MATERIAU (ELAS_FO=_F (E=E_F, NU=NU_F,),);

CM=AFFE_MATERIAU (MAILLAGE=M,
                  AFFE=_F (TOUT= OUI, MATER= MA),
                  AFFE_VARC=_F (NOM_VARC='NEUT1', CHAMP_GD=CHYOUNG),
                  );

However, I must admit I've never used EPSI as function parameter.

I hope it can be useful,

Joan

Last edited by joanBO (2019-06-19 16:31:01)

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#6 2019-06-21 13:16:31

phoenix22
Member
Registered: 2017-02-20
Posts: 25

Re: E_Young varies by EPSI or DIVU

Hi joanBO,
It's really so good to see your reply.

However, I still do not know how to use "NOM_VARC" as you said, I think that may be suitable only in the case of E = Function(Coord).

I found a similar topic on /viewtopic.php?id=13791
Then I do not know how to use the function of Sigma=f(EPSI) into DEFI_MATERIAU as Mr. Jmp mentioned as below
        # FT1 is the final curve, ready to use in DEFI_MATERIAU
         FT1=RECU_FONCTION(TABLE=T1,PARA_X='EPSI',PARA_Y='SIGM')

I am trying to make the loop for the E_Young as a function of EPSI by manual Python scripts.

It is so complicated because each step needs to be checked the convergence of Epsi, and if does not meet the pre-selection then this step must be updated the LIST_INST, the input parameters, so forth.

Regards, Tran.

Last edited by phoenix22 (2019-06-23 20:43:36)

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