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abaqus is not recognising my imperfection input from buckle analysi

abaqus is not recognising my imperfection input from buckle analysi

abaqus is not recognising my imperfection input from buckle analysi

(OP)
Hi all,

I ran a buckle analysis to get the buckling modes and then copied the .fil and .prt files with the cae file to a new folder, renamed the .fil and .prt files. I also replaced the buckle step with a Rik's analysis step. I then remove the modal file and node file commands in my keywords. After doing all these I ran the risk analysis, the structure just behaves like there is no imperfection inputed. So, I thought to remove the imperfection file and the structure behaves excatly the same way. I dont know why Abaqus doesnt recognise the imperfection.

PLEASE HELP.

RE: abaqus is not recognising my imperfection input from buckle analysi

Did you add the *IMPERFECTION keyword into your Riks analysis input file?

Martin Stokes CEng MIMechE

RE: abaqus is not recognising my imperfection input from buckle analysi

(OP)
YES I DID

RE: abaqus is not recognising my imperfection input from buckle analysi

Okay, there are a few things to look at then.

Did you use the first buckling mode as the trigger, or a combination of modes?

What scaling factor are you using, and how did you decide what factor to use?  For shells, I use a percentage of the shell thickness to start, say 10%.

I used to try a number of scaling factors, and then plot them against the collapse load to see what effect it was having on the structure.

Martin Stokes CEng MIMechE

RE: abaqus is not recognising my imperfection input from buckle analysi

(OP)
I did use the first mode and varied my scaling factor from below 1 and up to 100 still its the same.

I tried running the Riks analysis without the imperfection file, and the results i am getting is exactly the same as when i included the imperfection file, so i presume its not seeing it at all.

 

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