Spring definition

There is some one to explane me how define spring (with lw stifness) on code-aster and attached it to 3D Model node (Hexa element).
I need to doing it to stabilize the solution during analysis!!!
Is possible to have a simple example?

Regards
Jacopo

ciao Jacopo

spring elements are defined using these 2 eficas-commands:

FEMLin=AFFE_MODELE(MAILLAGE=MeshLin,
AFFE=(_F(TOUT='OUI',
PHENOMENE='MECANIQUE',
MODELISATION='D_PLAN',),
_F(GROUP_MA='SPRING',
PHENOMENE='MECANIQUE',
MODELISATION='2D_DIS_T',),),);

CARELEM=AFFE_CARA_ELEM(MODELE=FEMLin,
INFO=1,
DISCRET_2D=_F(CARA='K_T_D_L',
GROUP_MA='SPRING',
VALE=(0.25,0.25,),),
MASSIF=_F(GROUP_MA='ALL_FACE',
ANGL_REP=(0,0,),),);

In AFFE_MODELE You can declare 4 different element types:
2D_DIS_T
2D_DIS_TT
DIS_T
DIS_TR

This means spring element for 2D- / 3D-model and having only translational or also rotational DOFs.

in AFFE_CARA_ELEM the meaning of CARA='K_T_D_L' is:
K: stiffness matrix (not mass or damping)
T: only translational
D: diagonal matrix (no coupling between X- und Y-stiffness)
L: spring is based on a line element

An alternative to L is N: it needs no line element, but the springs are connected between a Node and the (fixed) environment.

Alternativ to T is TR

Alternativ to D is leaving out D. example: CARA='K_T_L'

And so on

As is clear (I hope) from Your input to CARA=' ' it depends how many values You must input at VALE=(0.25,0.25,...

In the outlined example, 2 values are necessary which have the meaning of X- and Y-stiffness of a line-based spring element in a 2D-Model

Johannes