Unilateral constraint and moving force with a given velocity

p.grillo

Hello everyone!!!

I'm new with Code-Aster and Salome-Meca!

I have some problems in modelling my case study (which is for my master thesis)

I have a long beam element (made of several beams and nodes) and on that I have to apply a distributed force upwards which has to move

along the beam with a certain velocity; I have , also, to limit the vertical movements of the beam and I think I need unilateral constraints lo limit

vertical movements up to +24 mm.

Unfortunately I don't have any idea how to model nor the distributed force which moves along the beam with a given velocity neither

unilateral constraints.

Sorry, maybe my problem has an easy solution but I can't find it!

Can someone please help me?

Thank you in advance!

p.grillo

Is there anyone that can help me please?

it's very important for me!!

Thank you!!

p.grillo

Hi everyone!!!

I tried to go on with my model and I was able to model an unilateral constraint!! :)

But still I need some help......is there anyone that can control what I've done and see if it is all correct?

I post my work!

Thank you very much!!!!

Ps: if it'll be correct...next step......moving force along beam!!!

Attached file:
Model_unilat.tar.gz, 103294kb

jeanpierreaubry

hello

if the matter is just to mimic a moving load there is an example on chapter 11 in my book

available here

http://framabook.org/14-beginning-with-code_aster/

otherwise 'SIGM_ELNO','SIGM_NOEU','SIEQ_ELNO', 'SIEQ_NOEU', are meaningless in beam anlaysis

that should raise an error at runtime an prevent printing the results

jean pierre aubry

p.grillo

Hello Jean Pierre,

first of all thank you very much for replyed me; then, yes, I'd like to simulate a load which moves along the beam (I think I'll use DYNA_NON_LINE); I downloaded your book and started meshing in GMSH (my first experience with FEM software!!). Sure, I'll take a look at your book for modelling moving load!! (Tranks!!!); it helped me very much!! As I saind in my first post, I'm new in Salome-Meca and in FE Analysis too; do you think I could simulate various scenarios changing the velocity of traslation along the beam of the moving load? I'd like to know the behaviour of beam when I change the velocity of the moving load.

I'd like to go on with my model but do you think it is now all right or should I have to change something?

Thank you very much again!!

Pietro

ThomasDESOZA

Hi,

If your beam neutral fiber is not too complicated (that is one coordinate is monotonous), you may use the FORCE_POUTRE loading in AFFE_CHAR_MECA_F to input a variable distributed force depending both on space coordinates (X, Y, Z) and time (INST).

TdS

p.grillo

Hello Thomas,

I'll take a look at those commands too!!

Thank you very much!!

Pietro

p.grillo

Hello Jean Pierre,

I've taken a look at your book; it has been helpful for me to understand how using a step function simulating a force moving along the cable!!

Unfortunately I have to take into account the changing place of the applied external force also with regard of the speed the force is moving along

the beam.

I know I have to use DYNA_NON_LINE but it's still not clear how I have to write the command file.

Is there anyone who can give me an example of the script?

Thank you very much!!

Pietro

p.grillo

Hello Thomas,

could you please give and example of what the script should be?

Sorry but I don't understand what you mean when you say

"you may use the FORCE_POUTRE loading in AFFE_CHAR_MECA_F to input a variable distributed force depending both on space

coordinates (X, Y, Z) and time (INST)".

Where can I find the "INST" command?

Thank you very much,

Pietro

p.grillo

Please, is there anyone that can help me?

p.grillo

Hello Thomas,

studying manuals and examples now I know what you mean with using of FORCE_POUTRE, but it is still not clear for me how using FORCE_POUTRE with coordinates (X, Y, Z) and time (INST) to simulate a load moving on a long beam (like a moving load on a bridge).

Unfortunately my distributed load is only 50 cm long (the entire length of the beam should be 10 m), do you thing I could use FORCE_POUTRE?

If I'm right the INST command (using DYNA_NON_LINE as in my case) gives me the possibility to link the concept of "time" to a list of numbers with its own time step; but what about changing the position of the load?

I tried to use :

TIME=DEFI_LIST_REEL(VALE=range(0,20,0.01)

POSIT=DEFI_LIST_REEL(VALE=range(0,100, 10)

func=DEFI_FONCTION(

NOM_PARA= 'INST'

VALE_PARA=TIME

VALE_FONC=POSIT

PROL_GAUCHE='EXCLU'

PROL_DROITE='EXCLU')

But my question is: how to link the position of the single loaded node (not considering FORCE_POUTRE in that case) to the POSIT list which represents the displacement of the force every 0.01 seconds (10 mm in that case)?

I don't know if I've been sufficiently clear.....I hope so!!

Thank you very much!!

Pietro