Ansys analysis hangs when run from Matlab

CF · 2012-05-24, 21:22

I am performing a material optimisation using the lsqnonlin function in Matlab. As part of this procedure, a call to Ansys is made and a finite element analysis is run:

dos('ansys140 -b -i FE_Analysis.inp -o output.txt');

When the above line is executed, Ansys hangs and a window pops up saying the program is not responding.

If I run this same Ansys input file (FE_Analysis.inp) outside of Matlab, it runs to completion without any problems. Also, when I fire up Matlab and execute the same analysis from the Matlab command line, there are no problems. If I try and run it from the Matlab command line after it fails when running through the optimisation script, it doesn't run.

Anyone have any idea what might be the issue? I don't think it is a memory issue. There are no messages other than "Program is not responding". I'm running it on a Windows 7 64 bit machine with 24 GB of RAM.

Thanks in advance for any input.

Cormac

**IceBreaker** · 2012-05-24, 23:13

I do not know the answer to your interesting question. It would be great if you post the solution once you've found one.

**Jorgen** · 2012-05-25, 05:35

I have basically stopped using Matlab (I use Python instead), but if I remember right there is another Matlab function that you can use to execute a system command. Perhaps that function is called "system('ansys...')" or something similar...

Also, what material model are you trying to calibrate?
The MCalibration software can calibrate all ANSYS material models, and supports 4-5 different optimization algorithms.

-Jorgen

CF · 2012-05-25, 10:15

I've tried "system" and "!" and the response is the same. I might end up checking out python but I have my framework all set up in Matlab and am reluctant to spend time at the moment setting up another one. I used this procedure before running optimisations with Abaqus and never had a problem.

I'm optimising Ogden material parameters plus stress field parameters to fit a simulation to in vivo skin deformation data. I'll have a look at MCalibration but I suspect I need to use a full FE package.

C

**IceBreaker** · 2012-05-25, 10:27

I'd give guys at Red Cedar Tech (makers of HEEDS MDO) a call. I know HEEDS can drive ABAQUS and perform material calibration. I am not sure about ANSYS. Ask for a trial license and see if it does the job for you.

CF · 2012-05-25, 13:23

Right. I think I found a solution but it seems fairly random and doesn't explain why it is happening.

In my script, I plotted two figures at the start to visually compare the model and experimental results. When I comment out the code to plot the figures, the ansys analysis runs without any problems.

C

**IceBreaker** · 2012-05-25, 14:25

I believe I will need to do this at some stage too. Is there any guidance you could provide? Could you upload a simplified INP/script or a document that shows how to do it or something of that nature? I use ABAQUS.

CF · 2012-05-28, 13:51

Seems like my solution was only addressing a symptom of another problem. On the second iteration of my optimisation, Ansys hangs like before.

If I use fminsearchbnd there are no problems.

C

**Jorgen** · 2012-05-28, 18:55

Cormac: You may want to try the MCalibration software - I can give you a free trial license.
MCalibration is very cool

and can calibrate any ANSYS material model.

-Jorgen

CF · 2012-05-30, 13:15

Problem is a Matlab 2009b issue. With Matlab 2011 there are no problems.

Thanks Jorgen. I may have a look into MCalibration software in the future.

C