nonlinear buckling solution settings

[skjoex]

Hi,

i am doing nonlinear buckling analyse and use the following settings in order to have the constant increment of loading up the first bisection :

NLGEOM, ON
NROPT , FULL
NCNV , 2
LNSRCH, 1
AUTOTS, ON
TIME , 100
NSUBST, 50, 5000, 50

but i noticed that after some bisections the next increment of loading can be still increased by ansys because of AUTOTS, ON. Lets say that after the first bisection increment is lowered from
2.0 to 1.0, after the second one from 1.0 to 0.5. But when this substep converged, the next increment can be increased back from 0.5 to 1.0...

so how to force ansys v10 to allow only decreacing of increment of loading ?

in ansys v11 there is OPNCONTROL, OPENUPFACTOR, 1.0 - but this doesnt work in v11...

Regards,
lubo

 

[Stringmaker]

I think you're missing the whole point of automatic time-stepping. The point of the command is to implement an algorithm which continuously updates time-step size based on the number of equilibrium iterations required and convergence behaviour in an effort to optimize solution time. You can use NEQIT to specify a max number of equilibrium iterations before bisection occurs. Otherwise use NSUBST and specify time-stepping parameters yourself.