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issues with control card selection

Hello,

Recently I have purchased a student license and I am trying to use hypermesh for Non Linear analysis of a cylinder. I have never done any non linear analysis before and therefore do not know much about it. The cylinder has to be modeled for Mooney-Rivlin (Polynomial model).

- height: 3.57 mm
- diameter: 25 mm

Force is acting on the top surface while the bottom is contrained in all DOF. (Please refer the screenshot)

I have read from the tips and tricks provided by Altair that MATHE Bulk data entry is used to define the material properties for nonlinear hyperelastic materials based on generalized Mooney-Rivlin (Polynomial) model. But, I do not find this material control card in Optistruct, even though the T&T mentions it is solved using optistruct.

I am sure I have missed something. Since I know only the basic MAT1 control card, MATS1 provides the opportunity to choose non linear mterial property. But here I don't know in which step or where to find/apply NLGEOM.

I would be really grateful if someone could provide me with a guide or any details regarding non linear analysis.

Thank you

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Rahul_P1

When you create a material, right click in model browser > create > material for eg, in material type , you will find MATHE

See the practical aspects of FEA ebook - http://www.altairuniversity.com/free-study-guide-book/

And the tutorial in online help - OptiStruct > OptiStruct Tutorials and Examples > Tutorials > Large Displacement Finite Element Analysis:

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

Altair Forum User

Firstly, Thank you for your response, Further on the topic. While using the MATS1 > NLELASTIC

I was able to create the NLPARM control card, chose non-linear quasi-static analysis in the load step.

When I run the analysis I got an error saying the units must be defined, therefore I went to the analysis>control cards> units> SI.

This card was created. But now i'm getting a RADIOSS license file error when I am running the analysis.

Please let me know what I am doing wrong.

Thank you for your time.

EDIT: considering that by material type you mean, that MATHE is a card, it is not present in the material selection. Please see the screenshot for reference

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Rahul_P1

Could you please paste the license error here

Altair Forum User

*** ERROR # 4004 ***
RADIOSS license error.
*** SOME ERRORS WERE REPORTED DURING THE RUN,
*** PLEASE VERIFY RESULTS AS THEY MAY BE INVALID.

*** PROGRAM STOPPED: FATAL ERROR(s) ENCOUNTERED.

Please also read the previous post, I have edited and added screen shots

Thank you

Rahul_P1

I am afraid MATHE is only available with 13.0.110 the full version, not the 13.0 student edition,

Please see if you can type in the card into the input deck from help,

Please send us the input file using the dropbox below, so we can check the license error.

Altair Forum User

I have sent the file through the dropbox option. Thank you.

Rahul_P1

I am able to run the file without any license errors in 13.0 student edition at my end,

Could you please make sure you are running it from within optistruct, also delete settings files http://forum.altairhyperworks.com/index.php?/topic/13434-how-to-delete-settings-files/

if you still face issues, redownload and reinstall the software.

Altair Forum User

Thank you very much for the response.

By run, you mean, that optistruct analysis was carried out completely.

I am sure I'm running it from with in optistruct, but i'll carry out the analysis again after deleting the settings file.

Regards,

Rahul_P1

There are convergence issues in your model, so it does not give us results, however there are no license errors.

Altair Forum User

There are convergence issues in your model, so it does not give us results, however there are no license errors.

I'm still getting the license error even after deleting the app data and the temp folder.

I would like information about the NLPARM card, if i have left all values to default, is there a chance this error can occur ?

The error happens only in non linear analysis, after selecting the units control card

EDIT: if i run the check option i'm getting the license error. If i try to run the analysis I get a non convergence error as you have

mentioned in the previous post.

Do i solve for non convergence by meshing more finer ? or doing more number of iterations ?

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Rahul_P1

See Nonlinear Convergence Considerations in help, navigation - OptiStruct > User's Guide > Structural Analysis > Nonlinear Analysis:

Nonlinear Quasi-Static Analysis

for NLGEOM see Implicit Convergence Issues in OptiStruct > User's Guide > Structural Analysis > Nonlinear Analysis:

Geometric Nonlinear Analysis (RADIOSS Integration)