*CONTROL_ACCURACY
$# osu inn pidosu iacc
1 4 1
*CONTROL_IMPLICIT_GENERAL
$$ igs=1 would include geometric stiffness
$# imflag dt0 imform nsbs igs cnstn form zero_v
1 x.x 2
$*CONTROL_IMPLICIT_EIGENVALUE
$20
*CONTROL_IMPLICIT_DYNAMICS
$ Can use tdydth and tdybur to start as dynamic and transition to static (gets things snugged up).
$# imass gamma beta tdybir tdydth tdybur irate alpha
1 0.6 0.38
*CONTROL_IMPLICIT_SOLUTION
$$ ILIMIT=1 (Full Newton) may be beneficial for highly nonlinear problems.
$$ Start out using the default ILIMIT, and then switch to full Newton (ILIMIT=1) if iteration is erratic with
$$ norms behaving erratically. Vice versa, if full Newton is slow, with residual norms going down very slowly,
$$ try BFGS (ILIMIT > 1 with default being 11).
$# nsolvr ilimit maxref dctol ectol rctol lstol abstol
12 1.0000E-20
$ 12 1 1.0000E-20
$# dnorm diverg istif nlprint nlnorm d3itctl cpchk
1 4
$# arcctl arcdir arclen arcmth arcdmp arcpsi arcalf arctim
$# lsmtd lsdir irad srad awgt sred
$$ generally set lsmtd=4 but lsmtd=5 may help if highly nonlinear
4
*CONTROL_IMPLICIT_SOLVER
$$ lprint=3 if error in linear solver
$$ autospc=2 to NOT automatically set constraints where codes thinks it prudent to do so
$# lsolvr lprint negev order drcm drcprm autospc autotol
1
$# lcpack mtxdmp iparm1 rparm1 rparm2
$$ lcpack=3 for nonsymmetric linear solver (see Manual; doubles linear solver time)
3
$# emxdmp rdcmem
0.85
$*CONTROL_IMPLICIT_AUTO
$$ consider invoking automatic time step control if convergence is a problem
$# iauto iteopt itewin dtmin dtmax dtexp kfail kcycle
$ 1
*comment
- If an implicit analysis is sharing computing resources with other LS-DYNA runs and/or
with other applications, and a memory-related error occurs, try reducing RDCMEM
on Card 3 from the default of 0.85 to 0.50
- IMASS=1 (dynamic analysis) if there are any rigid body modes or if convergence difficult in static analysis
GAMMA,BETA = 0.60,0.38 to invoke numerical damping in dynamic analysis.
______________________________________________________
$ Comments regarding contact in implicit:
$ - Recommend MORTAR for non-tied contact but if using non-MORTAR contact, set IGAP=2
$ - If symmetry planes included, set ISYM<0 (node set of nodes on sym plane(s))
$ - MINFO=1 in *CONTROL_OUTPUT to print MORTAR penetrations
$ - Default for MORTAR is thatinit. penetrations creates stress. IGNORE=2 will prevent this per these
remarks in the Manual...
*comment
If initial penetrations are detected (reported in the messag file), then by default
these will yield an initial contact stress corresponding to this level of penetration.
IGNORE > 0 can be used to prevent unwanted effects of this. IGNORE
= 2 behaves differently for Mortar contacts than for other contacts. For
this option, the penetrations are not tracked, but the contact surface is fixed at
its initial location. In addition, for IGNORE = 2, an initial contact pressure can
be imposed on the interface by setting MPAR1 to the desired contact pressure.
Any rigid body motion due to initial contact gaps can be properly eliminated
with these settings.
$ - IGNORE=-2 (negative 2) is like 2 but contact between segments belonging to the same part is ignored,
that is, self-contact is ignored.