ABAQUS script for RIKS post-buckling analysis

[Tom_M]

Hi all,

I am trying to do a static RIKS post-buckle analysis by using a python script. I have managed to obtain my eigenvalues and managed to set up the RIKS step within python but I am now struggling to find a way of implementing my imperfection into my python code.

Previously I have done so by including smth like:

*IMPERFECTION,FILE=bucklingfile,STEP=1
1,1E-3

in my .inp file. Though I am not sure how I could do that within my script. Any advice would be greatly appreciated.

Thank you so much,

Tom

 

[FEA way]

That’s the right way to define imperfections. You have to save nodal positions from eigenvalue buckling analysis and then use *Imperfection keyword pointing to the results file from previous analysis and providing scale factor for each mode. Imperfections can’t be defined in Abaqus/CAE so it’s the only way whether you do it manually or with script.

 

[Tom_M]

Thanks for your quick reply.
I have tried to include something like this in my script:

Mymodel.keywordBlock.replace(3, """
** ----------------------------------------------------------------
*IMPERFECTION,FILE=MyBucklingModel,STEP=1
1,3E-3
** ----------------------------------------------------------------
**
** STEP: Riks
**""")

Though this gives me an error message and I am unsure how to solve it. I am unsure what the 3 in this code stands for and how I can refer to the correct part.
Do you have any experience with that?

 

[Mustaine3]

Run your part of the script that builds the model in A/CAE. Now add manually the additional lines into the CAE Keyword Editor. Those actions are also recorded as Python commands in the .rpy, so you can take them from there and add them to your script.

But you should generate some test models with your script and check in the .inp that the commands are actually in there and the location in the .inp is ok.

 

[Tom_M]

Thanks Mustaine3, I am currently attempting of doing that. Though, I am not sure if you came across a similar problem before but running my .py script in abaqus and then selecting edit keywords does not show my full model, as it is shown in my .inp, for some reason any ideas how I can fix that?

 

[Mustaine3]

The nodes and elements are automatically hidden, as it is not intended to edit them in this tool. But that's nothing you should worry about.
Just add the keyword after a certain other keyword.

 

[Tom_M]

Ok great thank you I will try that

 

[Tom_M]

If I run my python script it creates the model but keyword edit function does only show a very small part of it so it is impossible to enter the keyword attribute at a specific location.
Any advice on how i can get the full model in the keyword edit window? I am aware that nodes will not show but atm for me even steps do not show.

 

[Mustaine3]

I haven't tested this with Python, but when you say it is not working as desired, then I see no other option than writing the input file and adding the two lines there.