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#1 2018-06-01 21:10:05

eddie135
Member
Registered: 2018-06-01
Posts: 1

MOdal Analysis: creating rigid element for assigning point mass

Hi Salome-Meca users

This is my first post in which I have a question as a beginner. After searching through the forum regarding the creation of rigid elements I am still struggling to find a workaround.

I have a bracket which will be meshed as shell elements as per the Salome-meca tutorial 'How to perform a modal analysis'.

Additionally, I would like to create rigid element which is connected centrally to a series of nodes as shown attached. Here are the steps I took

Mesh Mode
1)I created a group of nodes on the circular edge.
2) Added a new node at the centre of circle and assigned this to the group above
3) Created a 0D element on this central node

AsterStudy - MOdel Definition
4) assigned a finite element for the shell elements via DKT
5) For the  0D element, I do not know what to assign? Additionally, when I select gorup of element in 'assign finite element' there is no 0D element available.

Anything suggestions or help on this topic will be greatly appreciated.
BEst Regards
Eddie

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#2 2018-06-02 18:40:58

dbpatankar
Member
From: Roorkee, Uttarakhand, India
Registered: 2010-05-22
Posts: 172

Re: MOdal Analysis: creating rigid element for assigning point mass

To assign mass to a 0D element, use M_T_D_N in AFFE_CARA_ELEM.

The image is not attached to this post so I am not sure about what exactly you want to model.

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#3 2018-06-03 08:18:09

ingladisa
Member
Registered: 2017-12-31
Posts: 55

Re: MOdal Analysis: creating rigid element for assigning point mass

eddie135 wrote:

Hi Salome-Meca users

AsterStudy - MOdel Definition
4) assigned a finite element for the shell elements via DKT
5) For the  0D element, I do not know what to assign? Additionally, when I select gorup of element in 'assign finite element' there is no 0D element available.

In AsterStudy, after read the mesh (i.e. named "mesh") you have to define a new mesh (i.e. named "MNmesh") including the added node (previously included in meshgroup "MNode"):

MnMesh = CREA_MAILLAGE(
CREA_POI1=_F(
GROUP_NO=('MNode', ),
NOM_GROUP_MA=('MNode', )
),
MAILLAGE=mesh
)
From this point your model mesh is this "MNmesh", no more "mesh".

Then, in model definition you have to include, together with the still done DKT:

model = AFFE_MODELE(
AFFE=_F(
MODELISATION=('DIS_TR', ),
PHENOMENE='MECANIQUE',
GROUP_ELEM=('MNode', )
),
MAILLAGE=MNmesh
)

And define (i.e. for concentrated mass = 5.0):

AFFE_CARA_ELEM (
...
DISCRET=(_F(
CARA=’M_TR_D_N’,
GROUP_MA=(’MNode’),
VALE=(5.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0)
), _F(
CARA=’K_TR_D_N’,
GROUP_MA=(’MNode’),
VALE=(0.0, 0.0, 0.0, 0.0, 0.0, 0.0)
))
...

To connect the MNode to the "slave" nodes (i.e. meshgroup "solide") you have two ways.
By full solid link:

load = AFFE_CHAR_MECA(
...
LIAISON_SOLIDE=_F(
GROUP_NO=('MNode', 'Solide')
),
...

Or by RBE3 type link:

load0 = AFFE_CHAR_MECA(
...
LIAISON_RBE3=_F(
COEF_ESCL=(1.0, ),
DDL_ESCL=('DX-DY-DZ', ),
DDL_MAIT=('DX', 'DY', 'DZ', 'DRX', 'DRY', 'DRZ'),
GROUP_NO_ESCL=('Solide', ),
GROUP_NO_MAIT=('MNode', )
),
...

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