OS-1500: Nonlinear Implicit Analysis of Bending of a Plate

Hi Ram,

Please go through these case studies: http://www.altairatc.com/india/bangalore/technical-presentations.htm

Dear George,

I had tried to solve my problem using  Geometric non-linear Implicit Dynamics analysis .

Total run time is for 21 seconds but it is solving for 15 seconds then shows the below error.

Following error occurs after some iterations.

MESSAGE ID :           79

 ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO TIMESTEP LIMIT **

      ISTOP=-2

Please provide your guidelines.

Thanks

RAM

Hi Ram,

When the time step is smaller than the input minimum one (please check /IMPL/DT/STOP), RADIOSS will stop the run with this message.

The reason is generally due to the convergence issue (DT_min). There is no general workaround for convergence issue, as outlined below:

1.Check the model, constraint conditions, materials, contact interface defines and so on.

2.Switching other convergence criteria (see Itol in /IMPL/NONLIN).

3.Try /IMPL/NONL/SMDISP to see if the issue came from geometric nonlinear

Dear George,

After reducing the minimum timestep DT in TSTEPNL ,

i didn't get this error.

Following error occurs after some iterations.

MESSAGE ID :           79

 ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO TIMESTEP LIMIT **

      ISTOP=-2

But it shows this error

Please provide your guidelines

Thanks

RAM

Below are the suggested workarounds for error   ISTOP=-4:

1.Check which solve method is used in /IMPL/SOLVER. Use another solve method.

2.Another frequent case is when the model is relatively large and the available free disk is not large enough.  If the issue came from memory management, you could also force RADIOSS to use out-of-core resolution (/IMPL/SBCS/OUTCORE).

Please try with these options.

Dear George,

How to change the solver method?

Thanks

RAM

Hi Ram,

I presume that you are working on OptiStruct Profile.

Create a load collector with SOLVTYP as card image and Create/Edit it. You will get the options to change the solver type. Try with AUTO which automatically selects between BCS and PCG type.

Finally, edit the load step and recall the  SOLVTYP you have created.

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

Dear George,

Yes ,i am using Optistruct and created the load collector with SOLVTYP card as you mentioned.

I am choose analysis type as Geometric Nonlinear Implicit dynamic analysis  in Solver Definition in load step

In SUBCASE option ,the SOLVTYP is not available  and unable to recall it.

please give your valuable suggestions

Thanks

RAM

Hi Ram,

Ill update you regarding this.

Hi Ram,

It is not possible to change the solver type for dynamic cases.

Please share the .out file.

Dear George,

Shared files in your dropbox

Thanks

RAM

Dear George,

Please find the image attached for the results getting from my side. 

Thanks

RAM

<?xml version="1.0" encoding="UTF-8"?>