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$$$$ EPSI     NOTICE  PV        12/03/20    21:15:09     7302           
                                             DATE     12/03/20

    Operateur EPSI                           Voir aussi : RTEN CALP
    --------------                                        ELAS    HOOK   
                                                          GRAD    POLA   
    1)   EPS1 = EPSI   MODL1 DEP1 ( CAR1 ) (HOO1) ('NOER') | ('II'  ) ;
                                                           | ('LINE') ;

    2)   EPS1 = EPSI  MODL1  GRAD1  | ('GEOM') | ;
                                    |  'DEPL'  |


    Description :
    ___________
    
    Pour la premiere syntaxe le calcul des deformations se fait, 
pour chaque modele elementaire, suivant la methode precisee au niveau 
du modele. En standard les termes quadratiques sont calcules si le code le
permet. (Voir mot-cle EPSILON des operateurs OPTION ou MODE)
 
    Cet operateur permet aussi de calculer un champ de deformations
en prenant le logarithme naturel d'un champ de gradient
symetrique ( EPS = ln(1/2.Ftrans.F) ) (2-eme syntaxe).
    For the first syntax this operator enables to calculate 
a strain field using the method defined for each model. By default quadratic
terms are computed if it is possible for the kind of element.
    It is also possible (2-nd syntax) to compuite strain by 
the natural logarithm of a symmetric gradient field 
( EPS = 1/2.ln(Ftrans.F) ).

    For some elements (beams, pipes, thin shells, with or
without transverse shear), it is a matter of generalized strains,
i.e. membrane-type strains and curvature variations. For the joint
elements, it is a matter of relative displacements. The strains for
the solid elements are computed in the general basis, those for
the shell, plate, and beam elements are computed in the local axes.


    This second possibility is now available only for the massive
formulation. The gradient field F is either given directly :
F = GRAD1 ('GEOM' option, by default), or determined from the
displacement gradient field : F = I + GRAD1 ('DEPL' option).


      Contents :
      __________


      'II'   : key word indicating that second-order strains
               are requested

      MODL1  : model object (MMODEL type)

      DEP1   : displacement fields (CHPOINT type)

      CAR1   : field of geometrical properties (MCHAML type,
               CARACTERISTIQUES subtype) required for some elements
               (beams, shells...)
               It is also composed of material properties for
               the DST shell element when Hooke's matrix field
               is missing.

      HOO1   : Hooke's matrix field (MCHAML type, MATRICE DE HOOKE 
               subtype) required for the DST shell element when CAR1
               does not contain the material characteristics

      'NOER' : keyword asking for ignoring the error in case of change
               of sign of the jacobian. In that case, EPS1 will be 
               a non null ENTIER.

      'II'   : keyword to use second order terms.

      'LINE' : keyword for linear calculation.

      GRAD1  : symmetric gradient field (MCHAML type, GRADIENT subtype)

      'GEOM' : keyword indicating that the gradient field GRAD1 is
               associated with a geometric transformation

      'DEPL' : keyword indicating that the gradient field GRAD1 is
               associated with a displacement field

      EPS1   : generated deformation field (MCHAML type,
               DEFORMATIONS subtype)


    Notes :
    _________

 1.  For offset shells, the strains are computed at the
 level of the offset mid-surface.

 2.  For 2D plane stresses, it is not possible to compute
 the strain in relation to the perpendicular direction with respect
 to the plane. It equals 0.

 3. The second order strains are calculated for the following types
    of elements :
        - full dimension elements : all
        - linear : BARR POUT TUYA TIMO
        - plates and shells : COQ2 DKT

 --------------------------------------------------------------------
 |                       Computed strains                           |
 |            Finite elements in MECANIQUE formulation              |
 --------------------------------------------------------------------
 |  Finite | Option for |     Strain      |Calculation|  Supporting |
 | element | calculation|     names       |    basis  |   points    |
 --------------------------------------------------------------------
 |  POI1   | PLAN GENE  |  EPSS           |  local    |   node      |
 --------------------------------------------------------------------
 |  CERC   |   AXIS     |  EPSS           |  local    |   node      |
 |         |   FOUR     |                 |           |             |
 --------------------------------------------------------------------
 |  BARR   | PLAN CONT  |  EPSS           |  local    |  centre of  |
 |         | PLAN DEFO  |                 |           |  gravity    |
 |         | TRID       |                 |           |             |
 --------------------------------------------------------------------
 |  COQ2   | PLAN CONT  | EPSS,EPZZ,RTSS, |  local    |   Gauss     |
 |         | PLAN DEFO  | RTZZ            |           |   points    |
 |         | AXIS       | EPSS,EPTT,RTSS, |           |             |
 |         |            | RTTT            |           |             |
 |         | FOUR       | EPSS,EPTT,GAST, |           |             |
 |         |            | RTSS,RTTT,RTST  |           |             |
 --------------------------------------------------------------------
 |  POUT   | TRID       | EPS ,GXY ,GXZ , |  local    |   nodes     |
 |  TUYA   |            | CX  ,CY  ,CZ    |           |             |
 --------------------------------------------------------------------
 |  TIMO   | TRID       | EPS ,GXY ,GXZ , |  local    |  centre of  |
 |         |            | CX  ,CY  ,CZ    |           |  gravity    |
 --------------------------------------------------------------------
 |  TUFI   | TRID       | EPS ,GXY ,GXZ , |  local    |  centre of  |
 |         |            | CX  ,CY  ,CZ    |           |  gravity    |
 |         |            | EPS7,EPS8       |           |             |
 --------------------------------------------------------------------
 |  TRI3   | PLAN CONT  | EPXX,EPYY,EPZZ, |  global   |   Gauss     |
 |  QUA4   | PLAN DEFO  | GAXY            |           |   points    |
 |  TRI6   | AXIS       | EPRR,EPZZ,EPTT, |           |             |
 |  QUA8   |            | GARZ            |           |             |
 |         | FOUR       | EPRR,EPZZ,EPTT, |           |             |
 |         |            | GARZ,GART,GAZT  |           |             |
 --------------------------------------------------------------------
 |  M1D2   | UNID PLAN  | EPXX,EPYY,EPZZ  |  global   |    Gauss    |
 |  M1D3   | UNID AXIS  | EPRR,EPZZ,EPTT  |           |    points   |
 |         | UNID SPHE  | EPRR,EPZZ,EPTT  |           |             |
 --------------------------------------------------------------------
 |  JOI2   | PLAN CONT  | DRSN,DRN        |  local    |    Gauss    |
 |  JOI3   | PLAN DEFO  |                 |           |    points   |
 |         | AXIS       |                 |           |             |
 --------------------------------------------------------------------
 |  JOI4   | TRID       | DRS1,DRS2,DRN   |  local    |    Gauss    |
 |         |            |                 |           |    points   |
 --------------------------------------------------------------------
 |  COQ3   | TRID       | EPSS,EPTT,GAST, |  local    |  centre of  |
 |         |            | RTSS,RTTT,RTST  |           |  gravity    |
 --------------------------------------------------------------------
 |  DKT    | TRID       | EPSS,EPTT,GAST, |  local    |  Hammer's   |
 |         |            | RTSS,RTTT,RTST  |           |   points    |
 --------------------------------------------------------------------
 |  DST    | TRID       | EPSS,EPTT,GAST, |  local    |  Hammer's   |
 |         |            | RTSS,RTTT,RTST, |           |   points    |
 |         |            | GASN,GATN       |           |             |
 --------------------------------------------------------------------
 |  COQ4   | TRID       | EPSS,EPTT,GAST, |  local    |  Gauss      |
 |         |            | RTSS,RTTT,RTST, |           |  points and |
 |         |            | GASN,GATN       |           |  centre of  |
 |         |            |                 |           |  gravity    |
 --------------------------------------------------------------------
 |  COQ6   | TRID       | EPSS,EPTT,GAST, |  local    |    Gauss    |
 |  COQ8   |            | GASN,GATN       |           |    points   |
 --------------------------------------------------------------------
 |  CUB8   | TRID       | EPXX,EPYY,EPZZ, |  global   |    Gauss    |
 |  TET4   |            | GAXY,GAXZ,GAYZ  |           |    points   |
 |  PRI6   |            |                 |           |             |
 |  PYR6   |            |                 |           |             |
 |  CU20   |            |                 |           |             |
 |  TE10   |            |                 |           |             |
 |  PR15   |            |                 |           |             |
 --------------------------------------------------------------------
 |  LISP   | TRID       | EPZZ,GAXZ,GAYZ, |  local    |    Gauss    |
 |  LISM   |            | RTXX,RTZZ,DJP   |           |    points   |
 --------------------------------------------------------------------

 
 
 

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