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Syntax problem: Apply rotation

  • Jakob Andersen
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15 years 4 months ago #3700 by Jakob Andersen
Syntax problem: Apply rotation was created by Jakob Andersen
Hi all,

I am trying to model stresses induced by the rotation of the blades of a wind turbine using code aster.

I have gotten the hang of doing the preprocessing work in Salomé MECA and afterwards creating a .astk case using the CAELINUX wizard. until now, the PRES_REP and FORCE_FACE BC's have worked fine, but now I need to define a proper force working on the volume itself.

My approach has been to create a .comm file using Salomé's linear elasticity wizard and then editing the pressure boundaries created using the using a text editor.

I am looking to rotate my entire model around a point [x y z]=[0 0 0] and around the y-axis ([0 1 0]) at approximately 360 RPM.

My french is not as good as it once were, making the documentation on the CODE_ASTER site hard to decrypt - google translate is, I admit though, a useful tool. The solution does not seem to be in the non-french docs.

I am sure the solution is simple, but any input (as specific as possible please :) ) on how to do this would be greatly appreciated!

Best regards (and a happy new year to you all)

Jakob Andersen

BTW: I have attached the .comm file created by Salomé MECA. It has two boundaries - one 'b1' is the fixed boundary and the other 'profile1' is where I would in other cases use a FORCE_FACE or PRES_REP condition for approximating the rotational forces. Also, the density is not defined (rho should be for steel: 7.85g/cm3).<br /><br />Post edited by: Jakob Andersen, at: 2010/01/02 13:19
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15 years 4 months ago #3702 by kwou
Replied by kwou on topic Re:Syntax problem: Apply rotation
Hoi Jakob, cealinuxers,

First I wish everybody a Happy Newyear.

It is quite easy to apply gravity and rotational (though when you say it is easy, it wonot). You can use the following snippets in your command file:

....
#gravity
g = 9810.0
xp = 0.0
yp = 0.0
zp = -1.0
gravity=AFFE_CHAR_MECA(MODELE=FEMLin,
PESANTEUR=(g,xp,yp,zp),);

#PESANTEUR = (g, ap, bp, cp),
#where the amplitude of the load is rho * g, so you need to define rho in the correct units.

arot = 0.0
brot = 1.0
crot = 0.0
xrot = 0.0
yrot = 0.0
zrot = 0.0
omega = 1.0
rotation=AFFE_CHAR_MECA(MODELE=FEMLin,
ROTATION=(omega,arot,brot,crot,),
CENTRE = (xrot,yrot,zrot),);

#amplitude of load is: rho*omega*omega, rotate around (arot,brot,crot)
#centre of rotation is CENTRE (but this did not always work
correctly ....), but since (0,0,0) is default, you donot need it

result=MECA_STATIQUE(MODELE=FEMLin,
CHAM_MATER=material,
EXCIT=(_F(CHARGE=gravity,),
_F(CHARGE=ratation,),
_F(CHARGE=others,),),);
.....


I am not sure whether you can apply gravity to a part of the construction, maybe by adding a _F(GROUP_MA='volumepart',). Need to check for yourself at this moment.<br /><br />Post edited by: Kees Wouters, at: 2010/01/02 20:33
Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
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15 years 4 months ago #3703 by Jakob Andersen
Replied by Jakob Andersen on topic Re:Syntax problem: Apply rotation
Hi Kees,

Thank you for your quick reply!

I have tried to implement your snippets, but everytime I try to run the simulation, I get a syntax error (see attached .mess file).

I cannot figure out what is happening. i have tried to debug the comm tile, but it seems nothing is helping. The problem is my lack of knowledge of the Code_aster syntax.

Do you have any ideas?

Thanks again!

Attachment LinearStatics_3Dwng_Mesh1.zip not found

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15 years 4 months ago #3704 by kwou
Replied by kwou on topic Re:Syntax problem: Apply rotation
Hi Jakob,

I cannot open the unzipped file. Next error is displayed: ''not been able to detect the character coding''. Can you upload the mess file again (sorry if the fault is at my place).

Sometime later:
I have tried gravity and rotation (syntax only ...) on a simple block. Maybe it is helpful.
Uploading did not succeed. See next post.

kind regards - kees<br /><br />Post edited by: Kees Wouters, at: 2010/01/04 13:30
Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
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15 years 4 months ago #3705 by kwou
Replied by kwou on topic Re:Syntax problem: Apply rotation
now with attachment:

Attachment gravity-397e92570d4652560e22be9ab0ce6102.zip not found



Again, I see that the CENTRE keyword does not work. For the given example (a block with vertices [0,0,0] and [10*1*1] mm) , with omega increased to omega=100 rad/s the displacement of the axial top plane is 3.0 [mm]. This value remains the same when CENTRE is changed to say CENTRE=(10.0, 0.0, 0.0). So it seams that CENTRE is not implemented in the code.

Any comments on this issue?

kind regards - kees<br /><br />Post edited by: Kees Wouters, at: 2010/01/04 12:33
Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
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15 years 4 months ago #3706 by Jakob Andersen
Replied by Jakob Andersen on topic Re:Syntax problem: Apply rotation
Hi Kees,

Wow, thanks for the effort - I have been unable to get a proper comm file from my caelinux boot as I was running a CFD sim in windows on the same computer.

I looked at the files you've sent - does the comm file syntax work? I have tried to compare it to my own .comm file (attached along with the .mess file containing the error), but i cannot see what the syntax problem should be...

I still have CENTRE in there, which I guess would be the first thing to remove...

Best regards,

Jakob

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