geometric imperfections 2

[Hich]

I want to do a post buckling analysis with riks method. first I did a linear buckling analysis and now i want to write the results to a result file as a nodal data to do the geometric imperfections for riks analysis. does anybody know how I should do that?

 

[ESPcomposites]

You can simulate the imperfection as a small "side" load or moment. This will initiate the buckling.

Brian

http://www.espcomposites.com

 

[bassmanjax]

In your eigenvalue analysis run, you need to request output to a .fil results file. You can then use those results using the *IMPERFECTION, FILE=xxxxx keyword in your riks analysis.

There is a good example of this type of analysis in the ABAQUS docs - "Buckling of an imperfection-sensitive cylindrical shell"

Regards

Martin

Martin Stokes CEng MIMechE

 

[Hich]

How can I request output to a .file ? I am really in trouble

 

[bassmanjax]

Look up *NODE FILE in the keyword docs.

Regards

Martin

Martin

 

[Hich]

I used the following command but Aabaqus gives error with the *.

*NODE FILE, GLOBAL=YES, MODE=1, LAST MODE=1
^
SyntaxError: invalid syntax
>>>

Is it something wrong with using * ?

 

[ESPcomposites]

Try just *NODE FILE, without the parameters first.

You did request displacements on the second line as follows?

*NODE FILE
U

Other than that, check to make sure you placed it at the end of the deck (input file).

Brian

http://www.espcomposites.com

 

[Hich]

I think my first problem is that i don;t know where I have to write these commands. I use the command area which is at the same place of message area. is it correct?

 

[bassmanjax]

You have to edit the .inp file created by ABAQUS and add the *NODE FILE line into the .inp file, exactly as ESP stated above.

Martin

 

[Hich]

thank You Martin
I added this one to the input file. nothing happened. I submitted the job again but the input file was rewritten. then I decided aybe I can import the edited input file as a model but this time I faced this error:
WARNING: The following keywords/parameters are not yet supported by the input file reader:
---------------------------------------------------------------------------------
*NODEFILE
*PREPRINT

 

[bassmanjax]

*NODE FILE is not supported in CAE, so you'll have to write the .inp file out and edit it in a text editor (like Notepad). You then have to submit the job at the command prompt, not through CAE.

Open the ABAQUS command window in your working directory, then type;

abaqus j=myjobname

to run the job.

Martin

 

[Hich]

I don't know how to thank you Martin. I finally made the .fil output. then I made my model for Riks analysis and I opened its input file with notepad and I added *imperfection, file=mylastfile
and then in abaqus command prompt I ran the new input file. then I imported it to abaqus for analysis. but imperfection didn't affect the results!!

Regards

 

[Hich]

Dear Martin,
You gave me vary good clues. Problem is solved now. thank you

All the best