ANSYS APDL, unconstrained model error. 1

[Tachie8]

Hello

I am trying to model a concrete beam with BFRP supports and I have been having this error everytime I solve it.

"The value of UY at node 14 is 2.84937889E+11. It is greater than the current limit of 1000000. This generally indicates rigid body motion as a result of an unconstrained model. Verify that your model is properly constrained."

So I de-constructed the whole thing and built it up one by one structural element. And the error re appears even when its just a plain concrete beam (No links, No rbars) on supports (rigid and roller) and 2 loads.

I am wondering if someone can point out what I am doing wrong (any fundamentals I am forgetting), whether there is a way to fix this issue or change the setting on convergence or a tolerance limits or any other suggestion you might think is useful.

Many thanks.

 

[Tachie8]

Correction: BFRP links. Not supports.

 

[meshparts]

Hello,

can you post the code of the model (if available)?

Regards
Alex

MESHPARTS
Tuning Your Simulation

http://www.meshparts.de

 

[Tachie8]

Is it the log file you are referring to?

 

[meshparts]

If the model is created in Ansys APDL by GUI commands yes..., but please try to filter out things like zoom command.
If the model is created in Workbench, then the batch file created.

MESHPARTS
Tuning Your Simulation

http://www.meshparts.de

 

[Tachie8]

Will do! Many thanks for your help in advance Alex.

 

[Tachie8]

I recreated the beam I hope you can see the attached file. Thank you.

 

[Tachie8]

File

 

[meshparts]

Hi,

the solution is nonlinear due to the concrete material and nonlinear stress/strain curve.

I added some lines of code at the end of the file, before solving (time stepping, output control).

See:

[URL unfurl="true"]http://files.engineering.com/getfile.aspx?folder=648f5f44-d616-49ad-9230-8d6ed3d774d4&file=Sample_Beam.ans[/url]

Now if you run the file, you still get non convergence, but you can take a look at the last converged deformation. Choose the next-to-last result set and plot the stress, strain and deformation. You also have plastic deformation. I'm not a concrete specialist, so I cannot say what the problem is, but I suppose it's you material definition. Try to increase the number of stress/strain points. See if the results are still in the described interval.

Regards
Alex





MESHPARTS
Tuning Your Simulation

http://www.meshparts.de

 

[Tachie8]

Dear Alex
Thank you, I will try this right now and let you know if its any better.

As I have mentioned above this is the basic foundation of the compact beam. I have been remodelling it to create the log file for that as well. If you don't mind taking a look at that too, I will post that afterwards.

Thanks again!

 

[Tachie8]

Dear Alex,

The code you sent does produce a solution which is great to start with considering it used to not even go past that earlier so thanks so much for that.

Attached herewith is the real problem; much more elements added. I have tried filtering out code for zooming etc. So when you do have a minute please take a look at it.

Many thanks.

 

[Deji91]

Hi Alex and Tachie,
I'm having a similar error with my code. I'm trying to run a probabilistic analysis on a 3D Truss system. The FE analysis is fine but a similar error as the one Tachie was having comes up when i try to run a probabilistic analysis. Is it okay if I upload my code on here so you can have a look at it for me pls

 

[RJcivileng]

hi,
according to what i know this error message means that the beam fail i am now working on a concrete beam with ansys and i depend on this message to know that my beam fail
try this code

/SOLUTION
ANTYPE,STATIC,new
!solcontrol,on
OUTRES,all,all
RESCONTROL,DEFINE,ALL,1,1
NROPT,FULL, ,ON
CNVTOL,F, ,0.05,2, ,
DELTIM,0.001,0.0001,0.05
AUTOTS,1
LNSRCH,0
NLGEOM,0
NCNV,2,0,0,0,0
EQSLV,SPAR
NEQIT,100
TIME,1

but change this numbers "DELTIM,0.001,0.0001,0.05",because i do change them from model to another to get the convergence .
good luck