Restarting Abaqus/Explicit...

[score33]

I want to change the boundary conditions on my model when the stress in a certain component reaches a predetermined level.

Is the best way to do this using the *RESTART command?

 

[score33]

If *Restart is the best way, how do you either A) stop the analysis when a certain stress is reached or B) find out at which step/increment the stress was reached so that you can restart from there?

 

[gio1]

Depending on the accuracy you need on this stress value you should define an appropriate number of increments in the analysis STEP.

I would then launch and solve the complete analysis. Following solution I would go and look at the results in the component at each increment and take note of the increment at which the stress is closest to the predetermined level. You can then restart the analysis from this increment

Rgrds

Gio1

 

[score33]

That is what I have been doing... kind of.

I use the *EXTREME VALUE command, set HALT=YES, and OUTPUT=YES to get the restart state written when the variable exceeds the specified value.

I have not been allowing the step to finish since to get a restart at that exact interval I would need to set the
*RESTART, WRITE, NUMBER INTERVAL=
command to a high number.

So how do I start from an INCREMENT rather than an INTERVAL?

 

[GregLocock]

I'm not an Abaqus user, but doesn't restart just pick up from the last iteration?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[gio1]

When you run the initial analysis use
*RESTART, WRITE, NUMBER INTERVAL=1
because you don't know on which increment your stress value will occur, so you want to save results for restart at each single increment (INTERVAL=1).

If you use *EXTREME VALUE with HALT=YES the analysis will stop exactly where you wanted, so on restarting it you don't need to specify the INTERVAL (by default it will be the last one):
*RESTART, READ [, STEP= ,INTERVAL= ]

cheers

 

[gio1]

Sorry, I take that back: it is NUMBER INTERVAL that controls the frequency at which results are to be written (the higher the number the higher the frequency). However, independently of NUMBER INTERVAL, Abaqus/Explicit always writes results at the beginning and the end of the step. So if you use *EXTREME VALUE with HALT=YES you should not worry about NUMBER INTERVAL as the last available results (those you are interested in) will have been saved, and you can restart simply with
*RESTART, READ

 

[score33]

Ah... just figured out I was making a mistake with the
*RESTART, READ, STEP=1, INCREMENT=#

... had some syntax wrong.
That's why I went to the
*RESTART, READ, STEP=1, INTERVAL=#, END STEP command.


But the *EXTREME VALUE command seems to do exactly what I want anyway.


Thanks for everyone's help.