Ansys analysis hangs when run from Matlab

[CF]

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]

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]

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 (http://polymerfem.com/content.php?9-MCalibration)software can calibrate all ANSYS material models, and supports 4-5 different optimization algorithms.

-Jorgen

[CF]

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]

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]

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]

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]

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]

Cormac: You may want to try the MCalibration software - I can give you a free trial license.
MCalibration is very cool :cool: and can calibrate any ANSYS material model.

-Jorgen

[CF]

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

[IceBreaker]

Were you able to find out what exactly the problem was?

[CF]

Were you able to find out what exactly the problem was?

Nope. One of those problems that thankfully disappears with an update.

[IceBreaker]

Strange! Well, whatever gets the boat to float! :)

By the way, if its not a bother, I was hoping you could provide some instructions dealing with material calibration using MATLAB. Is there a webpage that may have helped? A book? Or do you have a document that you might be willing to upload? I may have to perform material calibration myself. It would be of immense value to me.

Thanks.

[CF]

Strange! Well, whatever gets the boat to float! :)

By the way, if its not a bother, I was hoping you could provide some instructions dealing with material calibration using MATLAB. Is there a webpage that may have helped? A book? Or do you have a document that you might be willing to upload? I may have to perform material calibration myself. It would be of immense value to me.

Thanks.

Attached are two files, which provide a very rough skeleton of the optimisation approach I took. Some further details of the bigger picture are here:
http://www.springerlink.com/content/x8p3777155625818/?MUD=MP

Hope that is of some help.

C

[IceBreaker]

Sure, this will get me started. Thanks!