The convergence tolerance

crazylittleapple · Post by **crazylittleapple** » Tue Apr 12, 2005 11:34 am

Could anyone please give recommendations about how to set the convergence tolerance?

silvia · Post by **silvia** » Wed Apr 13, 2005 9:12 am

i'd go with 10^-8 or so....

crazylittleapple · Post by **crazylittleapple** » Wed Apr 13, 2005 2:37 pm

Why so small?

Post by **fmk** » Wed Apr 13, 2005 3:15 pm

the tolerance is really up to you .. it depends on your model, your units, time step, what norm you are using, i.e. disp, unbalance, or a relative one, and of course what you would be happy with.

crazylittleapple · Post by **crazylittleapple** » Wed Apr 13, 2005 6:13 pm

Thanks a lot for you guys replies. Then, how can we know what value is good for the analysis?

From the manual, the tolerance is an absolute value (i.e, it is not a ratio, for example, for the force criteria, we set tol=0.1 means tol=0.1 N (SI units) ), right?

silvia · Post by **silvia** » Wed Apr 13, 2005 11:18 pm

the 0.1 if Newtons if that is the basic unit you are using, yes.

I want a small tolerance because i don't want the error to build up/propagate.

crazylittleapple · Post by **crazylittleapple** » Thu Apr 14, 2005 11:06 am

OK, I will try it. Thanks a lot for you guys's help.