#1 2009-07-24 12:41:00

Vincent

Member

Registered: 2009-01-23

Posts: 29

Hinge between beam-elements?

Dear forum users,

I am trying to model the suspension of a car, in order to apply physically correct loads to its chassis.I would like to model the various bodies of the suspension (wishbones, upright etc) as simple beam elements. However, these beams need to be interconnected by hinges/joints.

Is there any way in code_aster to prescribe relations between two end-nodes of different beams such as to have relative translations constrained, but relative rotations free?

Or is there any other way to model a hinge between two beams in Aster?

Thanks in advance,

Vincent

jeanpierreaubry

Guru

From: nantes (france)

Registered: 2009-03-12

Posts: 3,975

Re: Hinge between beam-elements?

hello

this is the way i proceed :

create a short line element at the end of the beam where the hinge is
mesh it with a seg2 element
put it in a specific group
i do all that in Gmsh

then in *.comm file
AFFE_MODELE (.......
                        _F(GROUP_MA='pin',
                            PHENOMENE='MECANIQUE',
                            MODELISATION='DIS_TR',), ........
AFFE_CARA_ELEM(..........
                                _F(GROUP_MA='pin', CARA='K_TR_D_L',
                                    VALE=(1e3,1e3,1e3,1e0,1e0,1e0,),), .......

this means creating a short element with specified stiffness on the end of the beam

as it seems that end releases do not exist in Aster as they do in Nastran, Samcef or many others codes

this means also making a specific meshing in that area!

then if anybody has a better way to do it i will take it

jean pierre aubry

---

consider reading my book
freely available here https://framabook.org/beginning-with-code_aster/

Vincent

Member

Registered: 2009-01-23

Posts: 29

Re: Hinge between beam-elements?

Hi Jean Pierre,

tnx for the reply, some workaround like this is what i was looking for!

Nevertheless, someone else pointed me towards the use of BAR elements.. Since they can only transfer tension/compression forces, they would be perfect to model my wishbones, but i'll try this out first.

Ill let you know how it works out!

Vincent

jeanpierreaubry

Guru

From: nantes (france)

Registered: 2009-03-12

Posts: 3,975

Re: Hinge between beam-elements?

hello

i do not use BAR but POU_D_T (Timoshenko beam with shear stiffness, doc U31101)

modele=AFFE_MODELE(MAILLAGE=maillage,
                    AFFE=(_F(GROUP_MA=('2c30','c30','c25','monteur', 'c60x30','bolt'),
                            PHENOMENE='MECANIQUE',
                            MODELISATION='POU_D_T',),
car_pou=AFFE_CARA_ELEM(MODELE=modele,
                        POUTRE=(_F(GROUP_MA=('c30','monteur'),
                                  SECTION='RECTANGLE',
                                  CARA=('HY','HZ','EP',),
                                  VALE=(h_sect,b_sect,ep),),

i get good results

jean pierre aubry

---

consider reading my book
freely available here https://framabook.org/beginning-with-code_aster/

Jacopo

Member

From: Colle di Val d'Elsa, Italy

Registered: 2008-02-05

Posts: 566

Re: Hinge between beam-elements?

Hi,
I think that all the hinge could be modeled using also the liaison_ddl.
Is it right?

---

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

jeanpierreaubry

Guru

From: nantes (france)

Registered: 2009-03-12

Posts: 3,975

Re: Hinge between beam-elements?

hello

Hi,
I think that all the hinge could be modeled using also the liaison_ddl.
Is it right?

you are probably right
but i have never used it yet

and the doc, U4.44.01 is incomplete: it says
"La condition cinémétique suivante sera appliquée :"
and then no conditionat all printed in the doc!!

using a DISCRET allows to get the forces in the joint in the .resu file
which is helpful, and required by the classification office in buildings!!

jean pierre aubry

---

consider reading my book
freely available here https://framabook.org/beginning-with-code_aster/

paolo.scarparo

Member

Registered: 2018-12-16

Posts: 2

Re: Hinge between beam-elements?

Hello everyone. years have passed. has the possibility of creating end-releases in code aster been implemented?