Buckling and Riks Analysis

[VAlexak]

thread799-269117

Hi everyone,

I am very new in Abaqus and I do not understand several basic stuff which might most probably be ridiculous to some of you.
Here is the situation I am dealing with.

I have a stiffened plate designed, for which I already have got the eigenvalues and thus critical loads.
I need to introduce these imperfections now for a Riks Analysis.

My questions are related not so much to what precisely I need to write in the keyword, but more in how is the model actually built in Abaqus. Let me explain:
I have so far (for buckling analysis only) constructed all relevant fields amongst which in the step there is the initial and Buckle step included. Also running the analysis of the job created, I get the eigenvalues.

Now for the Riks Analysis, how is it actually defined?...Do you add a separate step in the same cae file, or do you create a new cae file and get imperfections from buckle file?...or is it that you just after having run the buckle step, you replace the step with Riks and create a new job at the same car file???...

I have tried all these but I always get error messages which being not familiar with Abaqus I cannot really explain.
Moreover, I have used *node file at the keyboard, the file is created at the relevant folder..but when it comes to *imperfection, I get error message about displaced command and no matter where I paste it, I still get the same errors...or boundary conditions...
I am really lost and I have a dissertation to carry out so any help would be most welcome...

Thanks in advance,
Vaggelis